Home / Glossary

Plain-language definitions of common roofing terms — squares, valley, ridge, underlayment, drip edge, ice-and-water shield, flashing, and the impact/fire/wind rating classes.

5V crimp panel

An exposed-fastener metal roof panel recognized by its paired V-shaped ribs, a traditional look on coastal, farm and residential buildings. It is screwed through the flat areas between the ribs, and one maker lists 24 inches of coverage per sheet and requires solid decking and a waterproof underlayment under it.

Acrylic roof coating

A water-based elastomeric roof coating made from acrylic latex polymer with pigments and additives, which cures as its water evaporates and the polymer particles fuse into a film. ASTM D6083 sets its requirements, testing the liquid for viscosity and solids and the cured film for elongation, tensile strength, permeance, water swelling, adhesion, tear and fungus resistance.

ACV / RCV

Actual cash value (ACV) is the depreciated value of your roof at the time of loss; replacement cost value (RCV) is the cost to replace it new. Many hail policies pay ACV first and release the withheld "recoverable depreciation" after the work is completed and invoiced.

Adhered ice barrier left in place

A reroofing allowance for self-adhered membrane bonded to the deck. A roof replacement normally strips everything down to the deck, but IRC R908.3 lets an adhered ice barrier stay and be covered with another layer of ice barrier. ARMA likewise advises leaving such membrane in place unless the decking under it is damaged, because removing it damages the sheathing, and slicing or nailing down any areas that are not lying flat.

Air barrier (air retarder)

A material or system installed to cut air leakage into or through the building enclosure. To work it has to be continuous, so a full air retarder system includes transition accessories that carry it across joints between assemblies. It controls moving air, while a vapor retarder limits water vapor diffusion through materials.

Air sealing

Closing gaps, cracks, and penetrations in the ceiling plane so warm, moist indoor air cannot leak into the attic. Building-science guidance identifies air sealing as the root fix for ice dams because air leakage, not conduction, is often the largest source of attic heat gain.

Air-blown (oxidized) asphalt

Asphalt stiffened by bubbling air through the soft refinery residue, called flux, while it is hot; the heat and oxygen react with it and raise its softening point. Coating asphalt for shingles and roll roofing is made this way, sometimes with catalysts, and can also be modified with polymers before it reaches the production line.

Algae streaking

Dark brown to black stains, often running in streaks down the slope, caused mainly by airborne algae such as Gloeocapsa magma growing on the roof; most visible on light-colored roofs in warm, humid regions. A bleach-and-water treatment lightens it only temporarily, and algae-resistant shingles with copper granules are made to inhibit it.

All-risk (open-peril) and named-peril policies

An all-risk or open-peril policy covers any cause of loss it does not specifically exclude, while a named-peril policy pays only for the causes it lists. Even all-risk home policies usually exclude wear and tear, flood and earthquake, and along the Texas coast wind and hail may need a separate policy.

Alligatoring

A pattern of interconnected cracks, like an alligator's hide, that develops as asphalt, bitumen, mastic or coating surfaces age, including the coating on spray foam roofs. Sunlight oxidizes the material and it loses its volatile oils, and the resulting cracks may stay in the surface layer or run all the way through it.

Anchor lug (batten lug)

A projection on the underside of a clay or concrete roof tile, at its head end, that hooks over the upper edge of a batten so the tile hangs in place and cannot slip down the slope. Tile industry guidance counts a batten as fully engaged only when it is at least as thick as the lug is deep.

ANSI/CRRC S100

The Cool Roof Rating Council consensus standard, formerly called CRRC-1, setting how specimens are prepared and how the solar reflectance and thermal emittance of roof and wall surface products are measured, both when new and after aging. First approved by ANSI in 2010 and updated about every three years, it is the reference that energy codes and rating programs cite for cool-roof measurements.

ANSI/SPRI/FM 4435/ES-1

The test standard for metal edge systems on low-slope roofs, such as embedded edge metal, fascia and copings; it does not apply to gutters, which are tested under ANSI/SPRI GT-1. Section 1504.6 of the 2024 International Building Code requires edge systems on built-up, modified bitumen and single-ply low-slope roofs to be tested to its RE-1, RE-2 and RE-3 methods.

APP (atactic polypropylene)

A high-molecular-weight plastic made by polymerizing propylene, with its side methyl groups set at random along the chain. It is the main modifier in APP modified bitumen sheets. ASTM D6222 covers polyester-reinforced APP sheet, smooth (Grade S) or granule-surfaced (Grade G), as a material specification only, leaving uplift, fire and field strength to the design of the roof system.

Appraisal clause

A policy provision for resolving disagreements about the amount of a loss. Each side hires its own appraiser, the two choose an umpire, and the umpire settles any disagreement. The result binds both sides on the amount of loss but not on whether the damage is covered, and each side typically pays its own appraiser and half the umpire.

Approved (code term)

In the IRC and IBC, approved means acceptable to the building official, which is not the same as tested or certified. An approved agency is a testing, inspection or product certification body that the building official has accepted, so wherever the code calls for an approved material, method or instruction, the final judgment rests with the local official.

Apron flashing

A continuous flashing across the downslope face of a chimney, skylight curb or front wall, lying over the top of the shingles below and turning up the vertical surface, where counterflashing laps over it. At the sides of the same penetration it hands off to step flashing.

Architectural (laminated) shingle

An asphalt shingle built from two or more bonded layers, giving a thicker profile and dimensional appearance. Also called laminated or dimensional shingles, they dominate the residential market and generally carry higher wind ratings and longer warranties than three-tab shingles.

Architectural metal panel

A metal roof panel that must be laid over a continuous deck or closely spaced supports and keeps water out by shedding it down the slope, not by sealing its joints. Because it cannot span open framing and depends on pitch rather than sealed seams, it is the counterpart of the structural panel, which is designed to bridge purlins or joists.

Area divider

A raised, flashed assembly built on the roof, typically one or two wood members on a wood base plate anchored to the deck, that relieves thermal stress in the membrane where a full expansion joint is not required. It is also used to separate large roof areas or roof systems of incompatible materials, and can help in laying out tapered insulation.

Asbestos-cement shingles

Rigid roofing or siding shingles of cement reinforced with asbestos fiber, one of the building materials EPA lists as possible asbestos sources, and covered by their own ASTM specification separate from modern fiber-cement products. EPA advises leaving undamaged material alone, since fibers are released mainly when it is broken, cut or removed, and having removal or major repair done by trained, accredited asbestos professionals.

ASCE 7

The American Society of Civil Engineers standard Minimum Design Loads and Associated Criteria for Buildings and Other Structures, published in editions such as ASCE/SEI 7-22. The building codes lean on it for wind, snow and seismic loads, and engineers use it to calculate the uplift pressures a roof system must resist.

Asphalt primer

A thin, solvent-thinned liquid asphalt applied to a surface before hot bitumen or other asphalt materials so that they bond to it properly. The word primer is also used for the liquid wiped on single-ply laps before seaming, which raises the shear and peel strength of the splice, and for a primer that helps a protective coating grip spray foam.

Asphalt roof cement (plastic cement)

A thick, trowel-applied mix of asphalt, solvent and mineral fillers or fibers used to bed flashings, seal around penetrations and hand-seal shingles; it also goes by flashing cement or mastic. ASTM D4586 covers the asbestos-free product, which is formulated to resist flowing in summer heat and to stay pliable in cold, and ARMA warns that too heavy an application can blister shingles.

Assignment of Benefits (AOB)

A document that transfers a homeowner's insurance-claim rights and payments to a contractor. Signing one hands the contractor control of the claim, so homeowners should read it carefully and be wary of pressure to sign on the spot.

ASTM D1970

The ASTM specification for self-adhering polymer-modified bituminous sheets used as steep-slope underlayment for ice dam protection at eaves and valleys under shingle, tile or metal roofs. Where the IRC requires an ice barrier, a self-adhering sheet of this kind may be used, and the code calls for it to be labeled to D1970.

ASTM D3462

The ASTM material specification for asphalt shingles made from glass felt, coated on both sides with asphalt and surfaced with mineral granules. The IRC requires asphalt shingles to comply with it. It evaluates shingles as manufactured, not their performance after installation.

ASTM D4869

The ASTM specification for asphalt-saturated organic felt underlayment used under steep-slope roofing, written so the felt lies flat and resists wrinkling and shrinking if left exposed for up to two weeks. The IRC lists it among accepted underlayments in Types I through IV.

ASTM D8257

The ASTM specification for mechanically attached polymeric roof underlayment used in steep-slope roofing, the standard written for fastened synthetic underlayments. Its stated aim is a water-shedding layer that performs both before and after the primary roof covering is installed.

Attic condensation

Water that forms on the underside of the roof deck and framing when warm, moist indoor air reaches the attic and meets surfaces colder than its dew point. It can soak insulation, grow mold and rot the deck; common causes are air leaking through ceiling penetrations, ductwork in the attic, and blocked or undersized ventilation.

Attic ventilation ratio (1/150 and 1/300)

The sizing rule in IRC Section R806.2: an attic's net free vent area must be at least 1/150 of the vented floor area. It may drop to 1/300 when 40 to 50 percent of that area is in upper vents no more than 3 feet below the ridge and, in Climate Zones 6, 7 and 8, a Class I or II vapor retarder is installed on the warm-in-winter side of the ceiling.

AZ50 and AZ55 (aluminum-zinc coating weight)

Coating weight designations for ASTM A792 steel sheet, whose coating is 55 percent aluminum, 43.4 percent zinc and 1.6 percent silicon, the substrate sold as Galvalume and similar names. AZ50 means 0.50 ounce of coating per square foot and is the usual weight under painted panels; AZ55 means 0.55 ounce and is the usual weight for bare, acrylic-coated panels.

Back surfacing

The fine mineral material, such as sand or talc, applied to the underside of asphalt shingles during manufacture. It keeps shingles from sticking to production equipment and to one another when they are stacked and packaged in bundles.

Balanced ventilation

An attic ventilation system in which intake area at the soffits/eaves and exhaust area at or near the ridge are roughly equal, so cool air enters low and warm, moist air exits high in a continuous flow. Manufacturers and the IRC target a 40-50 percent split of vent area high near the ridge.

Ballasted roof system

A low-slope roof whose membrane is loose-laid, attached only at edges and penetrations, and held in place by the weight of river stone, crushed stone or concrete pavers placed on top. Stone sizes follow ASTM D448 gradations. The roof structure must be able to carry the added weight of the ballast.

Base flashing

The lower piece of a two-part flashing, which rests on the roof and turns up against a wall, chimney or curb to send water back onto the roofing. IRC R905.2.8.1 requires it to be corrosion-resistant metal at least 0.019 inch thick or heavy mineral-surfaced roll roofing, and the counterflashing above laps down over it.

Base sheet

The first ply of a multi-ply bituminous roof, such as a built-up or modified bitumen system, installed before the remaining plies. Base sheets are saturated or coated felts; fiberglass base sheets for built-up roofing are classified by ASTM D4601 as Type I or Type II.

Bath fan termination (exhaust into the attic)

Where a bathroom or other mechanical exhaust duct ends. IRC M1501.1 requires exhaust air to be discharged outdoors and specifically forbids venting it into an attic, soffit, ridge vent or crawl space, so a duct left blowing toward a soffit or ridge vent does not comply; M1504.3 then keeps the outdoor opening at least 3 feet from property lines, operable windows and doors.

Batten-seam roofing

A traditional metal roof in which pans run up the slope between raised wood battens, and a metal cap folded over each batten locks to the pans on both sides. The small gap between each pan's upturned leg and its batten lets the pans move with temperature, and the battens give the roof a bold ribbed look.

Bermuda seam panel

A metal roof panel profile with steps formed across the slope rather than up it, so the finished roof looks like horizontal courses of shingles instead of vertical seams. Like other architectural profiles it is water-shedding, relying on the roof slope rather than watertight joints to keep water out.

BIPV roof panels

Building-integrated photovoltaic panels applied directly to the roof deck, where they serve as the weather-shedding roof covering as well as the solar array, unlike racked panels mounted above an existing roof. IRC R905.17 treats them as a roof covering: 2:12 minimum slope, a solid or closely fitted deck, code underlayment and ice barrier, and listing to UL 7103 or to UL 61730-1 and UL 61730-2.

Bird stop (eave closure)

A preformed metal, clay, concrete or plastic piece fitted under the first course of profiled tile to close the curved openings at the eave. It keeps birds and pests out, lifts the first course into plane with the rest of the roof, and may be solid or vented. The industry installation manual calls for it on high-profile tile.

Blow-off

Loss of shingles in wind, usually after tabs that never sealed or were poorly fastened flutter until they tear free. Common contributors are high, missing or overdriven nails, a missing or misplaced starter strip at eaves and rakes, and cold-weather installations whose sealant had not yet bonded.

Board decking

An older roof deck of solid lumber boards, usually 1-inch nominal, instead of plywood or OSB panels. CertainTeed accepts it with gaps up to 1/4 inch but not beyond, and boards wider than 6 inches can move enough to buckle shingles; ARMA suggests covering board decks with code-compliant sheathing during a reroof.

Bridging

A recover method in which new shingles span across the old courses rather than nesting against them, typically when metric-size shingles go over English-size ones whose exposures do not match. Manufacturers generally prefer nesting where it fits, because it sheds water better and lies flatter.

Buckle (ridging)

A long, raised ridge in a roof membrane, often lying along joints in the insulation or deck below it, which can signal that something in the roof assembly is moving. The word ridging is used for the same condition.

Building official (AHJ)

The officer or designated authority charged with administering and enforcing the building code in a jurisdiction, often called the authority having jurisdiction or AHJ. The building official issues permits, performs or accepts inspections, and decides whether a product, method or approval is acceptable locally.

Building permit (roofing permit)

Written approval from the building official that must be obtained before a building is altered or repaired in ways the code regulates; reroofing is not among the model residential code's exempt items. The permit or a copy stays at the job site until the work is done, and the contract should state who will obtain it.

Built-up roof (BUR)

A multi-ply low-slope membrane assembled on the roof from layers of felts, mats or fabrics laminated together with hot bitumen (asphalt or coal tar) or cold adhesive. The top is protected by gravel embedded in a flood coat, a coating, or a granule-surfaced cap sheet.

Bundle (shingles)

The wrapped package asphalt shingles are sold in, sized so a whole number of bundles covers one square. Many laminated shingles are packed at 33 1/3 square feet per bundle, three bundles to the square, but coverage and shingle count per bundle vary by product and are printed on the maker's data sheet.

Burning brand test (ASTM E108 / UL 790)

A roof covering fire test in which a lit block of wood, the brand, is set on the covering to mimic a firebrand landing on the roof. Class A and B brands are dry Douglas fir and Class C brands white pine; the test runs until the brand burns out or the deck fails, and passing means no sustained flaming on the underside of the deck and no glowing debris falling through.

Butt edge

The lower, exposed edge of a shingle or of its tabs, the edge that faces down the slope toward the eave. Installers align butt edges to chalk lines to keep courses straight, and manufacturers measure exposure and headlap from it.

C-39 roofing license (California)

California's specialty contractor classification for roofing: installing and repairing surfaces that seal, waterproof and weatherproof a structure, with materials ranging from felt, tar and urethane foam to metal roofing, shingles, shakes, tile, slate and membranes. C-39 contractors must carry workers' compensation coverage even with no employees.

California valley

A closed valley variant in which one plane's shingles run across the valley, and the other side begins with a single row of shingles laid lengthwise along a chalk line 2 inches from the centerline, butt edge toward the valley. The field courses then butt into that row. Not every manufacturer permits it; those that do publish their own nailing and offset rules.

Cant strip

A beveled strip, commonly cut from fiberboard or perlite at a 45-degree angle, set where a roof meets a wall or curb so a bituminous membrane turns up the vertical surface without a sharp 90-degree bend that could crack or bridge. It is standard in built-up and many modified bitumen details.

Cap nail (button cap nail)

A roofing nail with a broad plastic or metal disc under its head, whose wide cap holds underlayment down over a larger area than a plain nail head. Where wind design is required, IRC Table R905.1.1(3) calls for ring or deformed-shank cap nails with caps at least 1 inch across, set 6 inches apart along laps and on a 12-inch grid between them, with a shank of at least 0.083 inch long enough to reach 3/4 inch into the sheathing or pass through it.

Cap sheet

The top ply of a built-up or modified bitumen roof, and of its flashings, usually surfaced with mineral granules that protect the bitumen from weathering. A granule-surfaced cap sheet takes the place of the gravel and flood coat used on aggregate-surfaced built-up roofs.

Cedar grades (No. 1 Blue Label, No. 2 Red Label, No. 3 Black Label)

Quality grades for cedar shingles and shakes under the Cedar Shake and Shingle Bureau grading rules. No. 1 Blue Label is the top roofing grade, all clear heartwood and edge grain; No. 2 Red Label allows limited flat grain, sapwood and defects above a clear butt; No. 3 Black Label allows unlimited sapwood and flat grain and a shorter clear portion at the butt.

Certi-label

The label a Cedar Shake and Shingle Bureau member mill tucks under the strap of each bundle of cedar shakes or shingles, showing the mill is subject to unannounced inspections by an accredited, independent third-party agency. Only CSSB mills may use it, so asking for a grade by label color alone, such as blue label, does not guarantee a Certi-label product.

Certificate of Insurance

A document from an insurer verifying that a contractor carries active coverage, such as general liability and workers' compensation. Colorado regulators advise homeowners to confirm the certificate directly with the insurer and ensure it is endorsed for roofing work.

Certificate of occupancy

A document from the building official allowing a building to be used or occupied, required under IRC Section R110 before first occupancy or a change of occupancy. Roofing on a home already in use changes neither, so the permit is closed by a passed final inspection instead, though local practice varies.

Chalk line

A string coated with powdered chalk, pulled taut across the roof and snapped to leave a straight guide line. Shingle installers snap lines to keep courses and cutouts aligned, because small size differences between shingles add up across a large roof into wandering butt lines and misaligned cutouts.

Chalking (metal roof paint)

A powdery white residue on a painted metal panel caused by ultraviolet light breaking down the paint resin. All painted metal chalks and fades to some degree over time; finish warranties usually cover only chalking and fading beyond a stated measured amount within a stated period.

Change order

A written amendment to a construction contract that changes its scope or price, such as adding deck replacement found after tear-off. It should be signed by both parties before the added work starts; California, for example, requires home improvement change orders in writing, signed in advance.

Chimney back flashing

Sheet-metal flashing on the upslope side of a chimney where no cricket is built. CertainTeed's detail bends it at least 6 inches up the masonry and 18 inches up the deck, with the shingle course above held back about 2 inches so water and debris clear the corner. The IRC requires a cricket instead once a chimney is more than 30 inches wide.

Claim notice deadline

The time limit for reporting a loss to the insurer, set by the policy and sometimes by statute. In Florida a new or reopened property claim is barred unless reported within 1 year after the date of loss, and a supplemental claim within 18 months.

Class 4 (UL 2218 impact)

The highest impact-resistance class under UL 2218, the steel-ball drop test. A Class 4 covering withstands a 2-inch steel ball dropped from 20 feet without the underside cracking. It reduces — but does not eliminate — hail damage risk.

Class A (fire)

The highest roof-covering fire classification under UL 790 / ASTM E108, corresponding to severe fire-test exposure (maximum resistance to flame spread, burning brands, and fire penetration). Classes B and C denote moderate and light exposure.

Clay roof tile

A roof tile formed from clay or shale and fired at high temperature, which fuses the particles into a hard, weather-resistant body. ASTM C1167 sorts clay tile into three grades by resistance to weathering and three types by profile, and it is sold both interlocking and non-interlocking.

Climate zone (IECC/IRC)

One of the numbered regions, 0 through 8, that the energy provisions of the IRC and IECC assign to US counties by heating and cooling degree-days, with a letter for moisture regime: A for moist, B for dry and C for marine. Roofing rules key off the zone, including the reduced attic ventilation ratio allowed in Zones 6 to 8 and the minimum attic insulation R-values.

Closed-cut valley

A shingle valley in which shingles from one roof plane run continuously across the valley and shingles from the opposite plane are trimmed in a straight line roughly two inches off the centerline. It is the most common valley treatment on asphalt-shingle roofs.

Closure strip (inside and outside)

A foam or metal filler cut to match a panel's rib shape and used to seal the openings the ribs leave at eaves, ridges and transitions. An inside closure sits under the panel, typically at the eave; an outside closure sits on top of the panel under ridge or transition trim. Both keep out wind-driven rain, insects and birds and are commonly set on butyl tape.

CLUE report

A claims-history report from the Comprehensive Loss Underwriting Exchange that most insurers check before writing or pricing a home policy. It shows claims filed on a property over the past seven years, including those from earlier owners, and a consumer can get one free copy a year from LexisNexis and dispute errors.

Coal-tar pitch

A roofing bitumen refined from coal tar, the dark cementing material left when coal is destructively distilled, used in place of asphalt in some built-up roofs and waterproofing, notably on dead-level and very low-slope decks. Roofing pitch is ASTM D450 Type I, and its equiviscous temperature is set at 25 centipoise, far thinner than the 125 centipoise used for mopped asphalt.

Coil coating

Painting or finishing sheet metal while it is still a flat coil, in a continuous factory line, before it is formed into roof panels, flashing and trim. Factory prepainted roofing metal is made this way, and a removable protective film is sometimes laminated over the finish during the same coil processing.

Cold curl

A slight upward lift at the edges of asphalt shingles during the cold months after installation, caused by the asphalt coating shrinking in low temperatures. ARMA treats it as a normal condition that corrects itself once sunshine or warmer air heats the roof, not as a defect in the product.

Cold roof

A roof assembly designed so the deck stays near outdoor temperature in winter, through ample ceiling insulation, air sealing, and outdoor air moving under the sheathing. A deck kept below freezing does not melt the snow on it, which removes the meltwater that refreezes at the eaves as an ice dam.

Collar tie

A horizontal member connecting a pair of opposing rafters near the peak. The IRC places collar ties in the upper third of the attic space, at least 1 by 4 inches nominal and no more than 4 feet on center, and lets a metal ridge strap take their place. It is a different part from a rafter tie, which sits lower and keeps the rafters from pushing the walls apart.

Colorado SB 38 (roofing contract law)

Colorado Senate Bill 12-038 (C.R.S. 6-22-101 and following) regulates residential roofing contracts statewide. It requires a written contract, gives homeowners 72 hours to rescind after their insurer denies the claim, and prohibits contractors from paying, waiving, or rebating the insurance deductible.

Competent person (OSHA)

Under OSHA's construction rules, someone able to spot existing and foreseeable hazards on the job who also has the authority to act promptly to eliminate them. The fall protection rules lean on the role repeatedly, from serving as the safety monitor on a low-slope roof to deciding whether fall arrest equipment that has stopped a fall is undamaged and fit to use again.

Components and cladding (C and C) loads

Wind pressures used to design the individual parts of the building skin, such as the roof covering, the sheathing and their fasteners, as distinct from the main windforce-resisting system, the set of structural elements that supports and steadies the building as a whole. IRC Section R905.1 requires roof coverings to resist the C and C loads of Table R301.2.1(1), and IBC Section 1504.4 does the same for attached and adhered commercial roof coverings.

Concealed-nail and exposed-nail methods

The two ways of fastening single-coverage roll roofing. In the exposed-nail method the nails are driven through the cemented overlap and stay visible on the finished roof; in the concealed-nail method they go into the course underneath and are hidden by the cemented lap of the next course. ARMA allows exposed nailing down to 2 inches per foot and concealed nailing down to 1 inch, and favors concealed nailing for longest life.

Concrete roof tile

A roof tile made of portland cement, water and sand or other aggregate, molded or extruded and cured, ASTM C1492 is its product standard, covering strength, freeze-thaw resistance, water absorption and permeability. Like clay tile it is laid on battens or fastened direct to the deck, and standard-weight tile weighs 9 pounds or more per square foot installed.

Conductor head

An enlarged catch basin at the top of a downspout that receives water discharged from a through-wall scupper or a gutter and funnels it down the pipe. Downspouts themselves are also called conductors.

Contractor acting as public adjuster

Negotiating a homeowner's insurance claim while also doing, or planning to do, the repair work. Texas bars a contractor from acting or advertising as a public adjuster on property it works on, and Florida bars contractors from interpreting policy terms or adjusting a claim for the insured unless they hold a public adjuster license.

Contractor license bond

A surety bond a contractor must keep on file to hold an active license, available to consumers harmed by defective construction or license-law violations and to employees owed wages. California's rose to 25,000 dollars on January 1, 2023.

Contractor's final payment affidavit (Florida)

A sworn statement a Florida contractor gives the owner when final payment comes due, stating that every lienor under its contract who served a notice to owner has been paid in full, or listing who has not. The contractor must furnish it at least 5 days before suing to enforce its own lien.

Cool roof

A roof surface designed to stay cooler in the sun by reflecting more sunlight (high solar reflectance) and shedding the heat it does absorb (high thermal emittance). Coatings, light-colored membranes and specially pigmented shingles, tile and metal can all qualify, lowering roof temperature and cooling demand, especially in warm, sunny climates.

Coping (parapet cap)

The weather covering over the top of a parapet wall, usually sheet metal on low-slope buildings, formed to shed water and lapped down both faces of the wall. As metal edge systems, copings are subject to wind-resistance testing under ANSI/SPRI/FM 4435/ES-1 where the building code requires it.

Copper or zinc strips

Strips of copper or zinc-coated metal placed at or near the ridge so that rain carries metal down the slope, inhibiting algae and moss; the effect weakens with distance, so large roofs need more than one strip. They are best added at reroofing, since retrofitting means exposed nails or breaking the shingle sealant bond.

Copper patina

The green surface layer that forms on copper roofing and flashing as acidic moisture in the air reacts with the metal, after the bright copper first darkens over months and years. It forms faster in marine, urban and industrial air than in clean, dry air, and once complete it adheres tightly and protects the copper beneath from further weathering.

Copper sheet weight (16 oz, 20 oz)

Sheet copper for roofing is specified by weight per square foot rather than gauge, so 16-ounce copper weighs 16 ounces per square foot (about 0.0216 inch thick) and 20-ounce weighs 20 ounces (about 0.027 inch). Sixteen-ounce is the common weight for flashing and standing-seam pans; 20-ounce is used for flat-seam roofing and more demanding work.

Core cut (test cut)

A small sample cut out of a low-slope roof to see how it is built: the surfacing and membrane type, roughly how many plies, the type, thickness and condition of any insulation, and the deck underneath. On spray foam roofs, cores also measure foam and coating thickness and how well the passes and coating adhere.

Corrugated metal roofing

Sheet metal formed into a continuous series of parallel waves, which stiffens thin sheet so it can span farther over lighter framing and go up faster. Corrugated iron was patented in England in 1829, and once zinc galvanizing arrived it was being used on American post offices, customhouses, train sheds and factories by the 1850s.

Cosmetic damage

Storm marks that change a roof's appearance without reducing its water shedding or service life, such as dents in metal panels or minor granule loss that leaves the shingle mat covered. It is the category that cosmetic-damage exclusions on some policies carve out of coverage.

Cosmetic damage waiver

An insurance exclusion (also called a hail or wind loss waiver or cosmetic loss limitation endorsement) stating that if hail dents a metal roof but does not cause leaks or impair function, the insurer will not pay to replace the dented panels. Common on metal-roof policies in high-hail states like Colorado.

Counter-batten system

A tile roof support in which vertical strips run up the slope beneath the horizontal tile battens, raising the battens off the deck. The gap lets any water that gets under the tile drain freely to the eave and lets air move beneath the tile. The vertical strips are also called strapping.

Counterflashing

A second layer of flashing, embedded in or fastened to a masonry chimney or wall, that laps down over the top edge of the base or step flashing beneath it. It prevents water from getting behind the primary flashing.

Course

One horizontal row of shingles or roll roofing laid across a roof plane from rake to rake. Courses are laid from the eave upward, each one lapping the course below, and are kept straight and at a uniform exposure with snapped chalk lines.

Cover board

A thin, tough board laid over foam insulation directly beneath the roof membrane. It protects the insulation from impact and foot traffic, prevents blistering where hot bitumen is applied over foam, and gives adhered membranes a firm, smooth surface. Common types are glass-faced gypsum, high-density polyiso, perlite, wood fiberboard and mineral fiberboard.

Cricket (saddle)

A small peaked structure built on the uphill side of a chimney or other wide penetration to split water and snow around it rather than letting them pile up behind it. The residential code generally requires a cricket behind chimneys more than 30 inches wide.

CRRC aged rating (three-year weathering)

The solar reflectance and thermal emittance a roofing product keeps after three years of outdoor exposure at a CRRC-approved test farm, where roof samples are tilted at 45 or 5 degrees, measured by an accredited lab and listed beside the initial values in the CRRC Rated Roof Products Directory. The CRRC rates products without setting minimums; the codes and programs that cite its ratings decide what counts as cool.

CSPE (chlorosulfonated polyethylene, Hypalon)

A rubber-like thermoset single-ply sheet based on polyethylene reacted with sulfonyl chloride, widely known by the DuPont trade name Hypalon and also abbreviated CSM. It is usually compounded to vulcanize by itself after it is installed, and it has been made in both vulcanized and non-vulcanized forms. ASTM D5019 is the classification for the sheet.

Curb-mounted skylight

A skylight fastened to the top of a raised frame, the curb, built on the roof around the opening. Curbs suit flat and low-slope roofs and make an old unit easier to swap out; under IRC R308.6.8, a unit skylight on a roof pitched below 3:12 has to sit on a curb at least 4 inches above the roof plane unless the maker's instructions say otherwise.

Cutout

The narrow open slot between the tabs of a strip shingle; the top of the slot is often called the keyway. ARMA recommends keeping every cutout and every end joint between shingles at least 2 inches away from any nail in the course beneath, and keyways that drift out of line are a sign of poor layout.

Date of loss

The date the damage occurred, which starts the clock on claim-notice deadlines. For weather claims Florida sets it as the date a hurricane made landfall or the date NOAA verifies the tornado, windstorm, severe rain or other event, so a storm record matters when a roof claim is filed months later.

Debris chute

An enclosed slide, closed in on all sides, used to send tear-off and other waste from a roof down to a dumpster. OSHA 1926.252(a) requires one of wood or equivalent material whenever materials are dropped more than 20 feet to any point outside the building's exterior walls.

Deck-mounted skylight

A skylight whose frame fastens directly to the roof deck around the opening, with no raised curb, and is sealed with adhesive underlayment and a flashing kit matched to the unit. It gives a sleeker look on the roofline but is not suited to low slopes. Under IRC R903.2.2, a unit skylight flashed per its maker's instructions is exempt from the cricket otherwise required behind penetrations more than 30 inches wide.

Declarations page (dec page)

The summary page at the front of a home insurance policy that names the insurer and lists the policy period, the premium, each coverage with its dollar limit, and the deductibles. On a roof claim it is the first place to look for a separate wind and hail deductible or a percentage deductible.

Deductible

The part of a covered loss the policyholder pays before the insurer pays anything, set either as a flat dollar amount or as a percentage of the insured value. On a home policy it is taken out of every claim rather than once a year, so if a roof repair costs less than the deductible, the insurer owes nothing.

Deductible waiver (deductible rebate)

A contractor's offer to absorb, waive or rebate the homeowner's insurance deductible, typically by padding the bill sent to the insurer. Texas makes it illegal, requires a deductible notice in insurance-funded contracts of 1,000 dollars or more, and lets insurers ask for proof such as a canceled check that the owner paid it.

Defensible Space

The managed area around a structure where vegetation and other fuels are reduced or removed to slow a wildfire and lower ember exposure. Colorado guidance divides it into Zone 1 (0-5 ft), Zone 2 (5-30 ft), and Zone 3 (30-100 ft).

Depreciation (insurance)

The loss in value of property from age, use and wear. On a roof claim it is the amount subtracted from replacement cost to reach actual cash value, so an older roof is depreciated more. Whether withheld depreciation is paid later after the work is done depends on the policy.

Derecho

A long, fast-moving windstorm driven by an organized line or cluster of thunderstorms, whose damage runs in one general direction along a wide path instead of a twisting track. The Storm Prediction Center counts an event as a derecho when the damage swath runs at least 250 miles, with gusts reaching 58 mph or more along the path and several separate gusts of 75 mph or stronger, among other criteria.

Design wind speed (Vult)

The wind speed a building at a given site must be designed for, read from the wind map adopted with the code (the IRC calls it the ultimate design wind speed) and expressed as a 3-second gust at 33 feet above open terrain. In the IRC it also sets which ASTM D7158 or D3161 shingle wind class is required under Table R905.2.4.1.

Designated catastrophe area (Texas)

The stretch of the Texas coast, 14 coastal counties plus parts of Harris County east of Highway 146, where owners who cannot get private wind and hail coverage can buy it from the Texas Windstorm Insurance Association. Construction there must be certified to the windstorm building code TDI adopts, now the 2024 IRC and IBC, across its Seaward, Inland I and Inland II zones.

Dew point

The temperature to which air must be cooled, with its pressure and moisture content unchanged, before it becomes saturated and water begins to condense. In an attic, any surface colder than the dew point of the air touching it, such as the underside of the roof deck on a winter night, will collect condensation.

Dissimilar-metal (galvanic) corrosion

Corrosion that occurs when two different metals touch, or water runs from one onto the other, with moisture acting as an electrolyte, so the less noble metal corrodes faster. Copper runoff onto Galvalume, zinc or aluminum is the classic roofing case; separation, compatible fasteners and matching flashing metals prevent it.

Dormer

A framed structure that projects from a sloped roof — usually holding a window — with its own small roof. Dormer sidewalls and roof-to-wall joints depend on step and kick-out flashing and are among the most common residential leak points.

Double coverage

An application in which the covered, lapped portion of each course is at least 2 inches wider than its exposed portion, so the deck carries at least two layers of roofing everywhere. A 12-inch strip shingle laid at a 5-inch exposure just meets that test, since 7 inches of it are covered.

Down payment limit (home improvement)

A legal cap on the up-front payment for a home improvement job. California caps it at 10 percent of the contract price or 1,000 dollars, whichever is lower, with no exception for special-order materials, and later payments under the written schedule may not run ahead of the work performed.

Downburst

A concentrated blast of wind from a thunderstorm downdraft: air chilled by evaporating rain or hail is heavier than its surroundings, drops to the ground and spreads out with damaging force. The Storm Prediction Center describes downbursts as about 4 to 6 miles across and lasting several minutes, and a storm system that keeps producing them over a long path builds a derecho.

Downspout (leader, conductor)

The vertical pipe that takes water from a gutter, scupper or conductor head down to a lower roof, the ground or a storm drain system; it is also called a leader or conductor. Where expansive or collapsible soils are known to exist, IRC R801.3 requires roof water to be collected and released at least 5 feet from the foundation walls or into an approved drainage system.

Drain sump

A deliberate depression built around a roof drain or scupper so water collects and flows into the outlet instead of standing just short of it. It is formed with a metal sump pan or by tapering the insulation down toward the drain bowl.

Drip edge

A metal flashing installed along the eaves and rakes that directs runoff away from the fascia and into the gutter, protecting the deck edge from water intrusion. Its installation is commonly required by building code — see the drip edge reference.

Drip edge laps and sequence

The IRC details for drip edge on shingle roofs: adjacent pieces overlap at least 2 inches, the metal reaches at least 1/4 inch below the sheathing and 2 inches back onto the deck, and it is fastened no more than 12 inches apart. Underlayment goes over the drip edge along the eaves but under it along the rakes, the same order the ARMA manual shows.

Dry-in

On a steep-slope job, the underlayment laid over the bare deck, or the act of laying it, which gets the deck covered ahead of the finished roofing; the felt used this way is sometimes called dry-in felt. NRCA notes that on low-slope work the comparable interim layer is usually called a temporary roof instead.

Dwelling coverage

The part of a home insurance policy that pays to repair or rebuild the house itself, roof included, when it is damaged by a peril the policy covers. Its dollar limit caps what the insurer pays for the structure, and many insurers require the house to be insured for at least 80 percent, or even 100 percent, of its replacement cost.

Eave

The lower edge of a roof, typically overhanging the exterior wall. Eaves are where gutters, drip edge, and eave ice-and-water protection are installed.

Eave riser

Any method or material that raises the nose of the first course of roof tile so it lies in the same plane as the field tile above, such as a metal riser strip, a raised fascia, a cant strip or a doubled first course. Where a raised fascia is used, a beveled strip or formed metal anti-ponding piece supports the underlayment behind it.

Edge grain (vertical grain)

Wood sawn or split roughly at right angles to the growth rings, so the rings run across the thickness of the shake or shingle. Grading rules limit or exclude flat grain in the top grades: No. 1 shingles must be all edge grain, and premium grade shakes differ from No. 1 shakes only in being 100 percent edge grain.

Efflorescence (concrete tile)

A white, chalky bloom or patchy discoloration on concrete roof tile, caused by free lime in the cement: calcium hydroxide reaches the surface and reacts with carbon dioxide to leave a salt deposit. It is temporary and does not harm the tile or its water shedding, and rain and air usually wear it away over time.

Elastomeric roof coating

A fluid applied to the roof in the field that cures into a rubbery film that can be stretched to double its starting length (100 percent elongation) and then spring back to its original size. Acrylic, silicone and polyurethane coatings are the common types, used to weatherproof an existing roof surface or to protect spray polyurethane foam.

Electronic leak detection (ELD)

Finding holes in a roofing or waterproofing membrane by measuring electrical conductance. The membrane is an electrical insulator, so test current passes only through a breach, returning through a conductive layer below; over foam insulation or protection board a conductive material must be placed directly under the membrane. ASTM D7877 is the guide, and the method works on exposed or covered membranes.

Ember Intrusion

The process by which wind-driven embers, the leading cause of home ignitions in wildfires, enter or ignite a structure by landing on the roof, collecting in gutters, or passing through vents and gaps, often well ahead of the flame front.

Ember-Resistant Vent

An attic, eave, soffit, or foundation vent designed or screened to keep wind-blown embers out, typically by using tested flame- and ember-resistant products or covering openings with corrosion-resistant metal mesh no larger than one-eighth inch.

Emergency adjuster license

A short-term adjuster license a state issues after a disaster so extra adjusters can work the surge of claims. Texas grants it for 90 days with no exam or fingerprint check, but the applicant needs a sponsor: a person or business holding an active Texas adjuster license, or an insurer licensed in Texas.

End lap

The overlap where the end of one roll of underlayment or roll roofing meets the start of the next within the same course. For felt underlayment under shingles the IRC sets end laps at 4 inches, staggered 6 feet from those in the course below; synthetic underlayments follow their maker's instructions, which often call for wider laps.

Enhanced Fujita (EF) scale

The 0 to 5 tornado rating put into use in the US on 1 February 2007, replacing the original Fujita scale. Surveyors compare what they find against 28 damage indicators, such as one- or two-family homes, and up to 8 degrees of damage to estimate a 3-second gust, from EF0 at 65 to 85 mph to EF5 at over 200 mph; the ratings are estimates from damage, not measured winds.

EPDM membrane

A synthetic rubber roofing sheet made from ethylene propylene diene terpolymer. It is vulcanized (cured), which makes it a thermoset: cured EPDM does not melt, so its laps are joined with primer and splice tape or adhesive rather than hot air. ASTM D4637 covers non-reinforced, scrim-reinforced and fabric-backed EPDM sheet.

Equiviscous temperature (EVT)

The temperature at which hot roofing bitumen reaches the viscosity that makes a proper bond between plies. For roofing asphalt it is about 125 centipoise for mop application and about 75 centipoise for a mechanical spreader, and the recommended working range runs roughly 25 degrees F either side of the EVT, measured at the mop cart or spreader.

Exhaust vent

A high vent at or near the ridge, such as a continuous ridge vent or box vent, that lets warm, moist attic air escape. Mixing two different exhaust types on one attic can short-circuit airflow and should be avoided.

Exposed-fastener metal panel

A ribbed or corrugated metal roof panel screwed through its face into the framing or deck, leaving every screw head visible. It is the least expensive metal roof, but the screws pin the sheets so they cannot slide with temperature changes, and the rubber sealing washer at each hole is the usual leak point if a screw is over- or under-driven or later backs out.

Exposure

The portion of each shingle or course left visible to the weather after the course above is installed — commonly around 5 to 6 inches on asphalt shingles. Exposure is set by the manufacturer, and installing outside it can void the wind rating and warranty.

Exposure 1

An APA bond classification for plywood and OSB made with exterior-type adhesive but not rated for permanent outdoor exposure; the other classification is Exterior. IRC R803.2.1.1 allows Exposure 1 roof sheathing, including where its underside is exposed, while panels designed to stay permanently exposed outdoors must be Exterior.

Extensive green roof

A thin, lightweight vegetative roof planted with hardy sedums, herbs and grasses that need little care once established. ANSI/SPRI VF-1 describes extensive systems as having 6 inches or less of growing media and weighing roughly 13 to 30 pounds per square foot, and the EPA puts typical media depth at two to four inches.

Fading and unfading slate

A color classification for roofing slate. Fading (weathering) slates change shade after exposure because of fine pyrite in the stone; in the weathering greens of New York and Vermont, 20 to 60 percent of the slates turn orange-brown, buff or gray. Unfading slates keep their color for many years, and color stability is no guide to how long a slate lasts.

Fall restraint system

A harness and fixed-length line tied to an anchor so that a worker cannot reach an open edge at all, preventing the fall rather than catching it. OSHA guidance recommends restraint systems be able to withstand 3,000 pounds or twice the maximum expected force needed to hold the worker back.

Fascia

The horizontal board mounted at the eave along the ends of the rafters, to which the gutter is usually attached. It closes off and protects the rafter tails.

Feathering strips (horsefeathers)

Tapered wood strips nailed along the butts of old wood shingles to even out the surface before new roofing is laid over them. Where a recover over wood shingles or shakes creates a concealed combustible space, IRC R908.4 also requires covering the old surface with gypsum board, mineral fiber, glass fiber or another approved material.

Fiber-cement roofing

Roofing shingles, shakes and slates made of cement reinforced with non-asbestos fibers. ASTM C1225 covers products of uniform, non-tapered thickness and texture, testing strength, water absorption, frost and heat-rain resistance; profiled products fall under C1530, and asbestos-cement shingles under a separate specification, C222.

Fiberglass mat

The glass-fiber reinforcing sheet at the core of a modern asphalt shingle, coated with asphalt and faced with granules. Glass mats arrived in the 1970s; earlier shingles were built on organic felt. The 2021 IRC requires asphalt shingles to comply with ASTM D3462, the specification for shingles made from glass felt.

Field, perimeter and corner zones

The regions into which wind design divides a low-slope roof. Suction is lowest in the field (the interior), higher along the perimeter, and highest at the corners, so ASCE 7 assigns each zone its own design pressure. Membrane fastening, adhesive coverage and insulation attachment are increased in the perimeter and corners to match.

Fire-retardant-treated (FRT) cedar

Cedar shakes or shingles pressure-impregnated with fire-retardant chemicals at a treating plant so the protection is permanent, not a surface spray. Treated material is labeled Class B or C, and Class B shakes in a special assembly can form a Class A roof. Fire-retardant and preservative treatments are separate and cannot be combined.

Fishmouth (edge wrinkle)

A half-cylinder or half-cone shaped opening along the edge of a lap or seam, left where a ply sheet wrinkled or shifted during installation instead of bonding flat. It is also called an edge wrinkle; on shingles the term describes a similar opening formed at a cut edge.

Fivex, Perfection and Royal (cedar shingle sizes)

Trade names for the three standard cedar shingle lengths: 16-inch Fivex, 18-inch Perfection and 24-inch Royal. Thickness is written as a count of butts over inches, so 5/2 means five shingle butts stacked together measure 2 inches; Fivex is 5/2, Perfection 5/2 1/4 and Royal 4/2.

Fixed clip

A one-piece standing-seam clip with no sliding part, so it holds the panel in place rather than letting it move. It suits snap-lock systems and short mechanically seamed runs, roughly under 20 feet, where thermal movement is small, and it is used on purpose on longer runs to pin a panel at one chosen point.

Fixed point (pinned zone)

The one place along a standing-seam panel run where the panel is deliberately fastened so it cannot slide, with the rest of the run left free to expand and contract away from it. The fixed point is usually at the eave, but designers sometimes pin panels at a ridge, a tie-in or mid-slope so movement goes in two directions and trim details stay simpler.

Flashing

Sheet-metal or membrane components that seal transitions and penetrations — around chimneys, walls, valleys, vents, and skylights — to keep water out of vulnerable joints. Most roof leaks originate at failed flashing.

Flat-seam (flat-lock) metal roofing

A metal roof made of small rectangular sheets, often 18 by 24 inches of 20-ounce copper, with edges folded into interlocking locks on all four sides and held by cleats. On slopes of 3:12 or less the seams are soldered, making it the one sheet-metal roof system watertight enough to handle standing water; it is also used on domes and very steep or curved surfaces.

Flat, medium and high-profile tile

The tile industry sorts roof tiles by the rise of their top surface. Low or flat profile tiles rise half an inch or less; medium profile tiles rise more than half an inch with a rise-to-width ratio of 1:5 or less; high profile tiles exceed 1:5 and include S-tile, barrel and two-piece mission. The class drives flashing, eave closure and nailer details.

Fleece-back membrane

A single-ply sheet, such as EPDM, TPO or PVC, laminated to a thick non-woven polyester fleece on its underside. The fleece makes a thicker sheet with added resistance to tears and punctures, and these membranes are commonly set in spray-applied low-rise foam adhesive. A strip along one edge is left without fleece so the laps can be seamed.

Flood test

A watertightness test in which drains are plugged and temporary dams built so water stands on a membrane; NRCA describes a depth of up to 2 inches at the high point, held for at least 24 hours. ASTM D5957 covers flood testing of plaza and parking-deck waterproofing with slopes up to 1/4 inch per foot but says it is not meant for building roof systems; a flowing-water test, with drains left open, is the alternative.

Florida 25 percent reroof rule

A rule in the Florida Building Code, Existing Building (Section 706.1.1): within any 12-month period, work that repairs, replaces or re-covers more than 25 percent of a roof or roof section requires the covering on the whole roof or section to be brought up to current code. Florida Statutes 553.844 carves out roofs built, repaired or replaced under the 2007 Florida Building Code or later: for those, only the portion being worked on has to meet current code.

Florida Product Approval

The statewide system under Florida Statutes 553.842 for approving building products, roofing among them, before they are used in construction in Florida. A product with statewide approval, identified by an FL number, cannot be made to undergo further local testing when used within the conditions of its approval.

Flying brand test (ASTM E108 / UL 790)

A roof covering fire test that checks whether burning roofing breaks away as flaming pieces that could start fires where they land. The deck gets a continuous gas flame, for ten minutes in Class A and B tests and four in Class C, under a 12 mph air current that is raised to about 18 mph when treated wood shakes are in the sample.

FM 4473

The FM Approvals test standard for hail resistance of rigid roofing, which fires freezer ice balls at the product instead of dropping a steel ball as UL 2218 does. Classes 1 through 4 correspond to ice balls of 1.25, 1.5, 1.75 and 2 inches in diameter.

FM Approved (roofing)

Certification by FM Approvals that a roof assembly or component meets its stated test standards. For membrane and built-up roofs, FM 4470 examines fire from above and below the deck, simulated wind uplift, hail, water leakage, foot traffic and corrosion of metal parts.

FM Class 1 (fire from below the deck)

The FM Approvals fire rating for combustibility from below the roof deck, the risk that a fire inside the building ignites the insulation and roofing above it. FM 4470 assemblies earn it by passing NFPA 276, which limits the heat the above-deck materials add to the fire, or FM 4880.

FM hail rating (MH, SH, VSH)

The hail damage rating FM Approvals gives low-slope roof assemblies under FM 4470. Moderate hail (MH) and severe hail (SH) ratings come from dropping a 1.19 lb steel ball from 81 or 141.5 inches onto new and UV-weathered samples, while very severe hail (VSH) uses 2-inch ice balls made to FM 4473, striking a roof surface held at 40 to 45 degrees F. Class 1-MH is the minimum for certification.

FM windstorm classification (1-60, 1-90)

An FM Approvals rating for a tested roof assembly. The leading 1 means Class 1, and the number after the dash is the uplift pressure, in pounds per square foot, that the assembly withstood for one minute; the test raises pressure in 15 psf steps. A 1-90 rating therefore means 90 psf of uplift, not a 90 mph wind speed.

Foam-set (adhesive-set) tile

Tile attached with patties of approved polyurethane foam adhesive applied to the underlayment instead of, or in addition to, nails or screws. Its allowed uplift resistance and the size and placement of the foam come from the product approval, and the foam will not bond to some polyethylene or silicone-surfaced underlayments.

FORTIFIED Roof

A voluntary construction and reroofing standard from the Insurance Institute for Business and Home Safety (IBHS). It calls for a sealed roof deck, deck attachment with 8d ring-shank nails at closer spacing, a wider drip edge over a fully adhered starter strip, wind- and rain-resistant attic vents and, for shingles, an ASTM D3161 Class F or ASTM D7158 Class H wind rating. An optional Hail Supplement adds impact requirements for the roof covering.

Four-nail pattern

The baseline fastening for a strip shingle: four nails placed in the nailing zone, with the end nails about an inch in from each edge. IRC R905.2.6 makes four fasteners per strip shingle, or two per individual shingle, the minimum, and requires more wherever the manufacturer's instructions call for more.

Four-point inspection

An underwriting inspection, used in Florida home insurance, of a home's roof, electrical, plumbing and heating and cooling systems. A Florida-licensed inspector certifies each system's condition with photos; for the roof that means the covering, its age and remaining useful life, the last permit date and visible damage or leaks.

Free-tab shingle

An asphalt shingle made without the factory strips or dots of self-sealing adhesive, so the sun does not bond its tabs to the course below. Any bond between courses has to come from hand sealing with asphalt roof cement; most shingles are offered in self-sealing versions instead.

French tile

An interlocking flat clay roof tile with a somewhat raised, contoured face cut by two deep vertical grooves, which carry water and throw strong shadow lines. A lug at its top engages the tile laid above it, and each tile is also nailed through two holes near the top, often with a dab of cement added.

FTC Cooling-Off Rule

A federal rule giving buyers until midnight of the third business day to cancel certain sales made at their home or at a seller's temporary location, including door-to-door home improvement sales such as a new roof. It excludes sales under 25 dollars at home and purchases needed to meet an emergency, and the seller must provide two copies of a cancellation form.

Fully adhered system

A single-ply roof in which the membrane is bonded to the insulation or cover board across its entire underside, using solvent or water-based bonding adhesive, low-rise foam adhesive, or a factory self-adhering backing. The type of adhesive and how much of it is applied are set by the manufacturer's specification for the warranty and wind rating being sought.

Functional damage

Damage that reduces a roof covering's ability to shed water or shortens its expected service life, such as punctures, tears and fractured (bruised) shingle mats. Because insurance policies and case law may define the term their own way, engineers and adjusters check the policy wording before applying it.

G90 galvanized steel

Steel sheet hot-dip coated with zinc to the G90 coating designation in ASTM A653: at least 0.90 ounce of zinc per square foot of sheet, counting both sides, or roughly 0.45 ounce per side. It is the standard galvanized weight for roofing and flashing; lighter G60 and heavier G185 coatings also exist.

Gable

The triangular section of exterior wall enclosed between the two slopes of a roof at its end. A gable roof slopes on two sides only; the inclined roof edges above a gable are the rakes.

Galvalume

A steel sheet coated with an aluminum-zinc alloy (roughly 55% aluminum, 43% zinc) that is the most common substrate for residential metal roofing. The coating combines aluminum's long-term barrier protection with zinc's sacrificial edge protection, substantially outlasting older galvanized steel.

Gambrel roof

A roof with two pitches on each side of the central ridge: a shallow upper section and a steeper lower section, with a gable at each end. It differs from a mansard roof, which breaks into two pitches on all four sides, and the line where the pitches meet is a slope change that must be flashed.

Gauge (metal panel)

The thickness of a metal roofing panel, where lower numbers mean thicker steel. 24-gauge is about a third thicker than 26-gauge, resists denting and oil canning better, and is generally considered the minimum for an engineered standing-seam system.

General Liability Insurance

Coverage that protects against property damage and bodily injury a contractor may cause during a job. Verifying a roofer's current general-liability coverage keeps the homeowner from being financially exposed for on-site accidents or damage.

Graduated slate roof

A slate roof whose courses diminish from eave to ridge, with the largest, thickest slates at the eaves and the smallest, thinnest at the top, graded by thickness, size and exposure. The pattern was used on large institutional and church buildings and on many Collegiate Gothic campus buildings.

Granule

The ceramic-coated mineral surfacing on asphalt shingles that provides color and shields the asphalt from ultraviolet degradation. Granule loss accelerates aging — a particular concern under Colorado's high-altitude UV.

Granule loss

The shedding of mineral surface granules from asphalt shingles. Some loss is normal from manufacture onward, since shingles carry more granules than needed to cover the mat; other causes include aging, manufacturing defects, scrubbing or pressure washing, and hail. It becomes a concern when bare asphalt is left exposed to sunlight.

Gravel stop

A flanged edge piece, usually metal, installed at the perimeter of an aggregate-surfaced roof so that its raised lip keeps loose gravel from washing off, while also giving the roofing a continuous, finished edge. Its flange is set into the membrane and sealed with strip flashing.

Green roof firebreak and area divider

Bands of stone ballast, pavers or other Class A roofing that interrupt a vegetative roof so a rooftop fire cannot run across it. Under ANSI/SPRI VF-1, firebreaks are at least 6 feet wide, and area dividers at least 13 feet wide split large green roofs into sections no bigger than 15,625 square feet with no side over 125 feet.

Ground snow load

The weight of snow on the ground, in pounds per square foot, that sets the snow a roof must be designed to carry; the IRC maps it in Figures R301.2(3) and R301.2(4), each jurisdiction records its value in Table R301.2, and a roof is designed for that snow load or the roof live load, whichever is greater. In areas mapped CS (case study) the value comes from site-specific study, and where it exceeds 70 psf the house must be engineered.

Growing media (green roof)

The engineered soil of a vegetative roof: a blend of inorganic materials such as expanded clay, slate or shale, sand, perlite and vermiculite with a share of organic matter such as compost. The mix matters for fire safety, since the inorganic part does not burn while media rich in organic material can support combustion, and in ANSI/SPRI VF-1 its inorganic portion can count as ballast.

Guardrail system

A barrier of top rail, midrail or equivalent, and posts set along an unprotected edge to keep workers from falling off it. OSHA 1926.502(b) puts the top edge at 42 inches, plus or minus 3 inches, above the walking surface, requires it to hold 200 pounds pushed outward or downward near the top, and calls for midrails or screens wherever no parapet at least 21 inches high is present.

Gutter

A trough run along the low, downslope edge of a roof that catches runoff and carries it sideways to the downspouts or drain leaders. From there the water drops through the downspouts to a lower roof, the ground or a storm water system.

Hail bruise

A hail impact that displaces granules and fractures the fiberglass mat beneath, leaving a soft, dark spot that gives slightly under thumb pressure. Bruises rarely leak right away, but the exposed asphalt weathers rapidly, which is why adjusters treat mat fracture as functional damage rather than cosmetic.

Hail damage threshold

The smallest hailstone size expected to damage a given roofing material. In one widely cited ice-ball study of 11-year-old shingles, damage began at about 1 inch on organic-mat three-tabs, 1.25 inches on fiberglass three-tabs and 1.5 inches on laminated shingles; age, condition, temperature and impact angle all move the threshold.

Hail size by object

The standard comparison scale used to report hailstone diameter: penny 0.75 inch, nickel 0.88, quarter 1.00, half dollar 1.25, walnut or ping pong ball 1.50, golf ball 1.75, hen egg 2.00, tennis ball 2.50, baseball 2.75 and softball 4.00. The Storm Prediction Center asks for measured sizes over object comparisons wherever possible.

Hail spatter mark

A fresh mark left where a hailstone struck a weathered or oxidized surface, most visible on faded metal such as air-conditioner cabinets, electrical boxes and metal window frames. Inspectors read spatter together with dents in soft metal and AC fins to estimate hail size and the direction the storm came from.

Hailstone density (hardness)

How solid and hard a hailstone is, which varies from storm to storm and stone to stone. Natural hail is generally less dense than freezer-made ice, which is why lab ice-ball impact tests are regarded as a worst case; size, shape, hardness, fall speed and impact angle together decide whether a stone damages a roof.

Hand-sealing

Bonding shingles down with spots of asphalt roof cement (ASTM D4586) instead of relying only on the factory sealant. It is called for on slopes steeper than 21:12, in very cold weather when the sealant may not activate before a wind event, and where cold foot traffic has broken the bond. Too much cement can blister the shingle, so follow the maker's spot size and count.

Handsplit and resawn shake

A cedar shake with a rough split face and a smooth sawn back, made by running a split blank diagonally through a bandsaw to yield two tapered shakes. It is the most common rustic shake, made in 18 and 24-inch lengths in medium and heavy thicknesses.

Hard slate and soft slate

Trade terms for how completely a slate was metamorphosed, not how hard it feels. Hard slate is denser, absorbs less water and lasts longer; soft slate absorbs more, weathers faster and is more prone to delaminating. The terms are commonly used to set expectations for service life and repairability.

Headlap

Measured the ASTM way, the distance from the butt edge of a shingle to the top edge of the shingle two courses below it, the narrow band where three layers of shingle stack; it is designed to be at least 2 inches. Some manufacturers use the word more loosely for the whole portion of a shingle covered by the next course.

Heat illness (water, rest, shade)

Illness that sets in when the body cannot shed heat as fast as it builds, with symptoms running from thirst, rash and cramps to heat exhaustion and heat stroke, the most severe form. OSHA names roofing among outdoor jobs where workers have suffered it, counts heat-absorbing roofs as a heat source, and urges water, rest and shade, with shorter shifts for new workers while they acclimatize.

Heat welding (hot-air welding)

Joining overlapped thermoplastic membrane sheets by melting the two surfaces with hot air and pressing them together with a roller, using an automatic walk-behind welder in the field and a hand welder at details and steep areas. Membrane specifications set a minimum fused width; for common TPO and PVC systems it is 1-1/2 inches.

High nailing

Driving shingle nails above the manufacturer's nailing zone. On laminated shingles a high nail can miss the lower layer, leaving it held only by adhesive so it can separate and slide off, and on any shingle it weakens the hold against wind. Manufacturers treat it as a workmanship defect that can put the warranty at risk.

High-density polyiso cover board

A cover board made from polyisocyanurate foam far denser and stronger in compression than insulation-grade polyiso, typically 1/2 inch thick with coated glass facers. It is lightweight and adds more insulating value than gypsum or wood fiber boards, about R-2.5 at 1/2 inch.

High-Velocity Hurricane Zone (HVHZ)

The part of Florida, defined in the Florida Building Code as Broward and Miami-Dade counties, that has its own chapter of roofing rules within the code, separate test protocols such as TAS 100, and product approval requirements such as Miami-Dade Notices of Acceptance.

Hip

The external angle formed where two sloping roof planes meet at a downward-sloping ridge. A hip roof slopes on all sides, with no vertical gable ends.

Hip and ridge nailer (stringer)

A board of the proper height fastened along the hips and ridge of a tile roof, sometimes set on metal riser brackets, to support the hip and ridge trim tiles and give them something to be fastened to. Commonly called a vertical stringer, a similar nailer can also sit under the cover pieces of two-piece mission tile.

Hip and ridge shingles

Shingles made or cut to wrap over the outside angles of a roof, the hips and the ridge, in overlapping pieces laid along the line. Most manufacturers sell matching cap products for this; in cold weather they must be warmed before bending over the peak, or they can crack.

Hip and valley factor

A multiplier applied to the plan length of a hip or valley to find its actual length, which is longer than the common slope because the line runs diagonally between two roof planes. Typical values run from about 1.453 at 4:12 to 1.5 at 6:12, and estimators use the result to size hip caps and valley material.

Hip and valley rafters

The sloping framing members that run along a hip or a valley, where the rafters of two adjoining roof planes meet. The IRC makes them at least 2 inches nominal thick and no shallower than the cut end of the rafters, braced at the ridge to a bearing partition unless designed to carry that load, and designed as beams where the roof pitch is below 3:12.

Hold-in-Trust Requirement

A Colorado rule under C.R.S. 6-22-103 requiring a roofing contract to state, in bold-faced type, that the contractor will hold any homeowner payment in trust until materials are delivered to the site or a majority of the work has been performed.

Home Ignition Zone

The concept, developed in fire research and used by the Colorado State Forest Service, that a home's wildfire survival depends on the combination of the structure's own ignitability and the defensible space immediately around it.

Hurricane deductible

A deductible that applies only to hurricane damage and only when a trigger in the policy or state law is met, such as the National Weather Service naming a storm or issuing a hurricane watch or warning. Triggers, amounts and how long the deductible stays in effect vary by state and insurer.

Hurricane-prone region

In the IRC and IBC, the US Atlantic and Gulf of Mexico coasts where the design wind speed for an ordinary (Risk Category II) building is above 115 mph, together with Hawaii, Puerto Rico, Guam, the Virgin Islands and American Samoa. Windborne debris regions, with their stricter opening protection rules, are drawn inside it.

IBC Chapter 15 (Roof Assemblies and Rooftop Structures)

The roofing chapter of the International Building Code, the commercial counterpart of IRC Chapter 9. The 2021 edition covers drainage (1502), weather protection (1503), wind and impact performance (1504), fire classification (1505), roof coverings (1507), rooftop structures (1511) and reroofing (1512), and its wind rules draw on the loads worked out under Chapter 16.

IBHS hail impact-resistant shingle rating

An independent performance rating that IBHS publishes for impact-resistant asphalt shingles, which it buys at retail and strikes with simulated hail meant to reproduce how natural hailstones hit, then scores for dents, tears, cracking and granule loss. Because products sold as impact-resistant do not all perform alike, the FORTIFIED Hail Supplement accepts only shingles rated Good or Excellent rather than any Class 4 label.

ICC-ES Evaluation Report (ESR)

A report from ICC Evaluation Service stating that a building product, often a new or alternative one, complies with the IBC or IRC, and listing the code sections or acceptance criteria used, installation requirements and conditions of use. Building officials use ESRs to decide whether to accept a product.

Ice barrier (IRC R905.1.2)

The code rule for eave protection where the jurisdiction records a history of ice damming. Under the 2021 IRC it is either two plies of underlayment bonded with cement or a self-adhering polymer-modified bitumen sheet, carried from the eave edge to at least 24 inches inside the exterior wall line, and at least 36 inches up the slope on roofs of 8:12 or steeper. Detached accessory buildings with no conditioned space are exempt.

Ice dam

A ridge of ice that forms at a roof's eave when melting snow refreezes, trapping water behind it that can back up under the roof covering. Ice-and-water shield at the eaves is the primary defense.

Ice-and-water shield

A self-adhering, waterproof membrane applied at eaves, valleys, and penetrations to protect against leaks from ice dams and wind-driven rain. In cold climates it is typically required along eaves; it seals around fasteners that are driven through it. See the ice and water barrier reference for the governing standard.

Ice-dam formation

The conditions that build an ice dam: snow on the roof while upper roof areas average above 32 degrees F and the eaves average below it. Meltwater runs down to the cold edge and freezes, the dam grows as long as melt keeps feeding it, and water pooled behind it can work under the shingles into the attic and walls.

IEBC (International Existing Building Code)

The ICC model code for work on buildings that already exist: its scope reaches repair, alteration, change of occupancy, addition and relocation. Its scope has an exception letting detached one- and two-family homes and townhouses up to three stories comply with either the IEBC or the IRC, so which applies to a house depends on what the jurisdiction adopted.

Impact resistance of low-slope roof coverings (IBC 1504.8)

The IBC requires roof coverings on slopes below 2:12 to show resistance to impact damage through ASTM D3746 or ASTM D4272 testing, or by passing the foot traffic test in FM 4470. The rule covers any covering installed on such a roof under Section 1507, and sits beside the 2,000-hour accelerated weathering requirement of Section 1504.7.

Impact-resistant roof discount

A premium reduction some insurers give for a roof covering rated for hail impact resistance under UL 2218 or FM 4473. Each insurer decides whether to offer it and how large it is, and a maker's impact rating for this purpose is not a promise of hail performance; one shingle data sheet states hail damage is outside its warranty.

Independent adjuster

An adjuster who is not an insurer's employee but is paid a fee by the insurance company to inspect and adjust its claims. A staff adjuster, by contrast, works in the insurer's own claims department; both work for the insurer, unlike a public adjuster.

Induction-welded attachment

A way of securing a TPO or PVC membrane without putting fasteners through it. Special plates are screwed down through the insulation first; the membrane is rolled out over them and an induction tool placed on top heats each plate so the underside of the sheet is welded to it. Laps between sheets are still heat welded as usual.

Infrared roof moisture survey

A night scan of a roof with an infrared camera, from the roof or from the air, to map wet insulation above the deck by its temperature difference from dry areas. ASTM C1153 sets the equipment, weather and operator conditions and calls for suspect areas to be confirmed by cutting in; it finds wet insulation, not where the water got in. Capacitance and nuclear back-scatter are the other common moisture survey methods.

Intake vent

A low vent, typically in the soffit or at the eave, that admits cool, dry outdoor air into the attic. Intake vents feed the bottom of a balanced ventilation system; insufficient intake is a leading cause of ventilation problems.

Intensive green roof

A deep, garden-like vegetative roof that can hold larger plants and even trees and often serves as usable outdoor space. ANSI/SPRI VF-1 describes intensive systems as having more than 6 inches of growing media and weighing roughly 35 to 100 pounds per square foot, so they need more structural support, investment and upkeep than extensive roofs.

Interlocking shingle

An individual asphalt shingle shaped to hook onto its neighbors so the locked joints, rather than a sealant strip, resist wind uplift. ARMA prefers open valleys with these shingles, because woven or closed-cut valleys would put nails at or near the valley centerline, and warns that an old interlocking roof may leave an uneven base for a recover.

Intermittent flame test (ASTM E108 / UL 790)

A roof covering fire test in which a gas flame is repeatedly applied to and removed from the test deck under steady airflow, on a schedule set by the class sought, to see whether fire penetrates to the deck. It is required unless the covering is limited to noncombustible decks, and the airflow runs until all flame, glow and smoke are gone or the sample fails.

IRC / IBC (International Codes)

The International Residential Code (IRC, for one- and two-family homes) and International Building Code (IBC, for commercial buildings) are the model codes that Colorado jurisdictions adopt — by edition, with local amendments — to govern roofing work.

IRC Chapter 9 (Roof Assemblies)

The roofing chapter of the International Residential Code. In the 2021 edition it runs from Section R901 to R908: fire classification in R902, weather protection such as flashing, crickets and drainage in R903, materials in R904, the rules for each type of roof covering in R905, above-deck insulation in R906, rooftop solar arrays in R907 and reroofing in R908.

Itemized (line-item) estimate

An estimate that breaks a repair into separately priced items of labor and material rather than one lump sum. Florida bars a contractor from signing an owner to a repair agreement on an insurance claim without a good-faith itemized estimate, and insurers there must send the policyholder any detailed adjuster estimate within 7 days.

KEE (ketone ethylene ester)

A high molecular weight thermoplastic polymer added to some PVC roofing membranes to make the sheet soft and flexible. Membranes marketed as KEE or KEE-enhanced are PVC-based sheets that include it, and they install the same way as other PVC, with heat-welded laps.

Keyway (wood roof joint)

The gap left between neighboring wood shakes or shingles in a course so they can swell with moisture without buckling. Shingles are spaced about 1/4 to 3/8 inch apart and shakes about 3/8 to 5/8 inch, and each keyway is offset at least 1-1/2 inches from the one in the course above so water never runs straight through.

Kick-out flashing

A small angled flashing installed at the bottom of a roof-to-wall intersection to divert runoff away from the wall and into the gutter. Where it is missing, water runs behind the siding and rots the wall sheathing — one of the most common and costly flashing omissions.

Labor depreciation

Depreciating the labor, overhead and other non-material costs of a repair, not just the materials, when figuring actual cash value. Whether it is allowed depends on the policy wording and state law; Kentucky's claims regulation, for example, allows it only where the policy provides for it.

Ladder angle (one-quarter rule)

OSHA 1926.1053(b)(5)(i) requires a non-self-supporting ladder, such as an extension ladder leaned against an eave, to be set so the distance from the foot to the top support is about one-quarter of the ladder's working length. The same rule sets a job-built wooden ladder with spliced side rails at one-eighth of its working length, and any ladder must stand on a stable, level base unless secured against slipping.

Ladder extension (3-foot rule)

OSHA 1926.1053(b)(1) requires a portable ladder used to reach a roof or other upper landing to extend at least 3 feet above that surface. Where the ladder is too short to do so, it must be secured at the top to a rigid support and fitted with a grasping device such as a grab rail.

Lap cement

An asphalt-based cement, specified under ASTM D3019, that bonds the overlapping plies of roll roofing into a watertight lap. It is thinner than asphalt roof cement. When exposed nails are used with it, ARMA says to drive them through the cement so the shank is sealed at the point where it enters the deck.

Level 1 alteration (IEBC)

The lightest of the three alteration levels in the International Existing Building Code: removing and replacing, or covering, existing materials, elements or equipment with new ones that serve the same purpose. Reroofing is handled here, in Chapter 7 (Section 705 in the 2021 edition), and only the new work, not the whole building, has to meet current energy requirements.

Lien waiver (lien release)

A signed document in which a contractor, subcontractor or supplier gives up lien rights for amounts paid. A conditional waiver takes effect only once the payment actually clears; an unconditional waiver releases rights immediately. Forms and rules are set by state law; California prescribes statutory forms.

Lifetime warranty

A warranty whose length is tied to a lifetime instead of a set number of years, which the FTC notes can confuse buyers unless it is clear whose life is meant. Shingle makers generally define it as the period the original owner owns the home, and may limit it to individual homeowners or cut it to a fixed term after a transfer.

Lightweight insulating concrete (LWIC)

A low-density fill of portland cement, water and entrained air, with or without a lightweight aggregate such as perlite, poured over a roof deck to insulate it and, by varying its depth, to build slope toward the drains. NRCA defines it by an oven-dry unit weight of 50 pounds per cubic foot or less.

Limited warranty (full versus limited)

Under federal warranty law, a written warranty is titled limited when it misses at least one federal minimum standard for a full warranty, for example by making the buyer pay labor or return a registration card. A warranty can be part full and part limited, such as full coverage for an early period followed by a pro rata credit, as in many shingle warranties.

Liquid-applied roof membrane

A continuous, seamless membrane formed on the roof from a liquid resin, supplied as one or two components depending on its chemistry and normally put down in two coats. A polyester or fiberglass reinforcing mat is typically embedded in the first coat, and some resins need an added catalyst or hardener before they will cure.

Listed and labeled

Two code terms for third-party product certification. A listed product appears in a published list from an evaluating organization that keeps inspecting production and states that the product meets identified standards; a labeled product carries that organization's mark. The IRC relies on both, for example requiring underlayment to bear a label naming the ASTM standard it meets.

Long-term thermal resistance (LTTR)

A standardized way of reporting the R-value of gas-filled foam insulation such as polyiso after accounting for aging. As the blowing agent diffuses out of the foam cells, thermal resistance drops; the LTTR method accelerates that aging on thin slices so the published R-value reflects performance over the service life rather than on the day the board was made.

Low-slope roofing

Roofing on pitches below roughly 3:12, which relies on a continuous waterproof membrane rather than shedding. Single-ply membranes (TPO, EPDM, PVC), modified bitumen, and built-up roofs are low-slope systems.

Low-slope shingle application

Asphalt shingles on slopes from 2:12 up to 4:12, the lowest range the IRC permits them. In that range the code requires two layers of underlayment, laid as a 19-inch strip at the eave followed by 36-inch sheets each lapped 19 inches over the one below, and the shingle maker may add conditions of its own.

Magnetic sweeper (magnetic roller)

A wheeled or handheld magnet run over lawns, planting beds, driveways and gutters to pick up dropped roofing nails and other metal debris after tear-off and installation. A thorough sweep protects tires, feet and mowers and is a standard final step on a residential roofing job.

Magnuson-Moss Warranty Act

The federal law, passed in 1975, that governs written warranties on consumer products with rules issued by the FTC. It requires a written warranty on a product costing more than 10 dollars to be titled full or limited, requires clear disclosure of terms, and forbids a company that gives a written warranty from disclaiming implied warranties.

Mansard (very steep slope) application

Shingle installation on slopes steeper than 21 inches per foot, such as mansard walls, where gravity and cold keep factory sealant from bonding reliably. ARMA calls for the manufacturer's fastener count and placement plus quarter-size spots of asphalt roof cement under each shingle, applied as it is laid, and a ventilated space behind the sheathing.

Manufacturer Certification

A credential granted by a roofing-material maker to contractors who meet its training, insurance, and installation standards. Certification often unlocks enhanced system warranties and signals an established company, though it is not required by Colorado law.

Manufacturer's installation instructions (code status)

Under the IRC a roof covering has to be applied according to both the code section for that product and the maker's installation instructions (Sections R904.1 and R905.1), so a nailing pattern, exposure or underlayment rule printed on the wrapper is enforceable at inspection. The instructions also matter for reroofing, since a recover is permitted where the new covering is installed to the maker's approved instructions.

Matching (insurance)

The question of whether an insurer must replace undamaged roofing or siding so repairs match what remains. Rules vary: Kentucky, for example, requires insurers to replace all items in the area for a reasonably uniform appearance when replacements do not reasonably match in quality, color and size, and other states handle it differently, so both policy wording and state law matter.

Mean roof height

The building height used to look up wind pressures: the average of the eave height and the height of the highest point of the roof, except that on roofs pitched at 10 degrees or less the eave height is used instead. The IRC tables of roof wind pressures are drawn up for a mean roof height of 30 feet and then adjusted for other heights and exposures.

Mechanically attached system

A single-ply roof held down by rows of screws and stress plates driven through the membrane into the deck at set intervals. The rows run along each sheet edge, and the next sheet overlaps them by several inches and is welded over the top, hiding the fasteners. Perimeter areas get narrower sheets or extra rows of fasteners to handle higher wind loads.

Mechanically seamed panel

A standing-seam metal panel whose seams are folded and crimped closed with a seaming tool on site, producing a tighter, more weather-tight joint with superior wind-uplift performance. It can be used on low-slope roofs, unlike snap-lock panels.

Mechanics lien

A claim against real property, created by statute, that secures payment for labor or materials used to improve it. An unpaid roofer, subcontractor or supplier may be able to file one on the house even if the owner paid the main contractor. Deadlines, notices and procedures vary by state.

Membrane base flashing

Strips or plies of roof membrane that seal the joint where the field of the roof meets a vertical surface such as a wall, curb or parapet. The base flashing laps over the edge of the field membrane and runs up the wall, and its top edge is then secured and covered by a termination bar, counterflashing or coping.

Membrane blister

A raised spot in a low-slope roof membrane where a pocket of air, sometimes mixed with water or solvent vapor, is trapped and builds pressure between plies or between the membrane and its substrate. Coatings can blister too, lifting from their base where the substrate absorbs water or corrodes beneath them.

Metric shingle

A strip shingle made to larger metric dimensions than the traditional 12-by-36-inch English-size shingle, and laid at a greater exposure, about 5 5/8 inches instead of 5. Recovering one size over the other takes extra trimming because the new and old courses fall out of step.

Miami-Dade NOA (Notice of Acceptance)

A product approval issued by the Miami-Dade County Product Control Section showing a roofing or building product meets the Florida Building Code, including its High-Velocity Hurricane Zone rules. Each NOA carries an approval number and expiration date, and other jurisdictions may accept it where their building official allows.

Microburst

A small, short-lived downburst: the National Weather Service defines it as a thunderstorm downdraft whose outflow covers an area less than two and a half miles wide, with peak winds lasting under 5 minutes. Microbursts may arrive with heavy rain (wet) or almost none (dry), and the most intense pockets inside them can leave damage that looks like a tornado's.

Mid-roof (in-progress) inspection

A permit inspection made partway through a roof installation to check work the finished roof will hide, such as underlayment, battens and flashings. Requirements vary by jurisdiction; Denver, for example, requires one on tile roofs before more than 30 percent of the tile system is installed.

Mil (membrane thickness)

A unit of length equal to 0.001 inch, the usual way to state the thickness of a roof membrane and of a coating film, whether measured wet as applied or dry after curing. It is easy to confuse with the millimeter, which is far larger at about 0.03937 inch.

Mineral stabilizer (filler)

A fine, inert mineral powder, such as ground limestone, slate, fly ash or trap rock, blended into the coating asphalt of shingles and roll roofing. ARMA credits it with raising the coating's resistance to fire and with helping weathering, flexibility and durability; NRCA describes it as an inorganic material that does not dissolve in water, mixed with bitumen.

Mineral-surfaced roll roofing

Asphalt roofing sold in rolls, typically 36 inches wide, with mineral granules on the weather side; smooth-surfaced roll roofing is dusted with talc or mica instead. The IRC allows mineral-surfaced roll roofing on solidly sheathed roofs down to a 1:12 slope and requires it to meet ASTM D3909 or ASTM D6380 Class M.

Minimum roof classification by construction type (IBC Table 1505.1)

The IBC table that sets the lowest fire class of roof covering allowed on a building according to its construction type, IA through VB. Class B is the minimum for most types and Class C for a few, unless the International Wildland-Urban Interface Code or a fire district demands more, so Class A is never the baseline requirement. Nonclassified roofing is allowed on some R-3 and U buildings with at least 6 feet of fire separation.

Modified bitumen

A low-slope roofing sheet of asphalt blended with polymers — SBS (rubberized and flexible) or APP (plastic and heat-resistant) — reinforced with a polyester or fiberglass mat. It is installed torch-applied, self-adhered, or in cold adhesive, usually in two plies.

Mopping (solid and spot)

Spreading hot bitumen by hand mop or with a mechanical spreader to bond the plies of a bituminous roof to each other or to the substrate. Solid mopping lays a continuous coat, while spot mopping puts the bitumen down in rough circles and leaves an unmopped grid between them. The bitumen is applied within about 25 degrees F of its equiviscous temperature, measured at the mop cart.

Mortar-set tile

Tile bedded in a pad of cement mortar placed on the underlayment, used for field tile in some regions and widely for hip and ridge tiles. Mortar used structurally must meet the approved mix and bed size; mortar used only to fill gaps and dress edges, called point-up, is cosmetic.

Nail gun trigger types (full sequential and contact)

The firing modes of pneumatic nailers. A full sequential trigger fires only when the safety contact tip is pressed to the work first and the trigger is then squeezed, and both must be released before the next nail; a contact (bump) trigger fires whenever both are engaged in any order, so holding the trigger down lets the user bounce-nail across flat work such as roofing. OSHA and NIOSH report that injury risk is about twice as high with contact triggers and name full sequential as the safest choice.

Nail pop

A fastener that has backed out of the roof deck, lifting or puncturing the shingle above it. Causes include underdriven or misplaced nails and deck movement from temperature and moisture swings; each pop is a potential leak and should be refastened and sealed.

Nail-and-bib repair (slate)

A method of securing a replacement slate: it is held by one nail driven through the joint between the two slates of the course above, and a bib of copper roughly 3 by 8 inches is slipped under that joint to cover the nail head. When several adjacent slates are replaced, removing them in a pyramid shape keeps the number of bibs needed to a minimum.

Nail-strip (fastener-flange) panel

A concealed-fastener metal panel fastened straight to the roof deck through a flange or slotted strip along its male leg, with the next panel's female leg snapping over to hide the screw heads. It needs no clips or seaming, which makes it one of the lower-cost standing-seam options, but because the panels are pinned to the deck they follow its imperfections and most profiles are limited to runs of about 25 feet.

Nailing zone

The band on an asphalt shingle, often marked with printed lines or a fabric strip, where the manufacturer requires nails to go: below the sealant strip but high enough to be hidden by the next course. On laminated shingles it lies over the double-thickness overlap so each nail pins both layers.

Nesting

A recover method in which the top edge of each new shingle is butted against the butt edge of an existing shingle, so the old courses guide the new ones and the new roof lies flat. It suits square-tab shingles with a matching exposure; the first new course is trimmed narrower to fit, and manufacturers prefer it over bridging.

Net Free Area (NFA)

The actual unobstructed open area of a vent available for airflow, measured after subtracting screens, louvers, and baffles. Attic ventilation is sized by net free area, not by a vent's overall physical dimensions, and IRC R806 states its requirements in these terms.

No-cutout shingle

A strip shingle whose exposed portion is one solid piece with no slots between tabs. Standard laminated shingles are no-cutout designs, which is why hand-sealing instructions for them place cement spots along the whole lower edge rather than under individual tabs.

No-Dollar-Limit (NDL) Warranty

A manufacturer-backed commercial or low-slope roofing warranty that covers the cost of repairing qualifying leaks and defects with no monetary cap, meaning the manufacturer pays the full repair cost regardless of amount. Requires installation by a manufacturer-approved contractor to specification and usually a post-install inspection.

No. 15 and No. 30 felt

Trade names for the two types of asphalt-saturated organic felt in ASTM D226, commonly called No. 15 felt (Type I) and No. 30 felt (Type II), both used as steep-slope underlayment; the IRC accepts either type under asphalt shingles in ordinary areas but only Type II where wind design is required.

Nominal design wind speed (Vasd)

The lower, allowable stress design wind speed that some referenced standards are written around, as opposed to the ultimate design wind speed (Vult) shown on current code maps. Where such a document gives no conversion, IRC Table R301.2.1.3 provides one: a Vult of 130 mph equals a Vasd of 101 mph, for example, and 150 mph equals 116 mph.

Non-Prorated Warranty

Warranty coverage that pays the full cost to replace defective material with no deduction for age, in contrast to prorated coverage. Manufacturers grant it only during an up-front protection period (for example GAF's Smart Choice Protection Period or CertainTeed's SureStart), then switch to prorated terms.

Noncombustible Zone (Zone 0)

The first 0 to 5 feet around a home, kept clear of mulch, dead vegetation, firewood, and combustible items. IBHS research found that an ember-resistant buffer in this zone can roughly halve a home's chance of igniting.

Nose clip (wind clip)

A metal clip that holds down the lower, exposed end of a roof tile against wind uplift and against sliding down the slope; it is also called a wind clip or tile lock. Clips are used on steep slopes and in high-wind areas, and in one tested attachment each tile is nailed and also held by a clip measuring 0.5 inch wide by 0.060 inch thick, nailed to the sheathing.

Notice of commencement (Florida)

A form a Florida owner records with the county clerk and posts at the site before an improvement starts, naming the property, owner, contractor, any payment bond surety and any construction lender. Lienors rely on it for notices, and unless it states a longer period it loses effect 1 year after recording, making later payments by the owner improper.

Oil-canning

The visible waviness or buckling that can appear in the flat areas of standing-seam and other flat metal panels. It is an aesthetic characteristic, not a structural defect.

Open valley

A valley in which the shingles on both planes are held back to expose a metal liner that carries the runoff. Open metal valleys shed debris, snow, and ice better than closed valleys, which makes them a frequent recommendation in Colorado's snow country.

Ordinance or law coverage

Coverage for the extra cost of bringing a damaged building up to current code during repair, such as added underlayment, ice barrier or deck work. Many policies exclude these costs unless an endorsement is added, and limits vary; Florida, for example, requires insurers to offer it.

Organic-mat shingle

An asphalt shingle built on a felt of cellulose fibers, saturated and coated with asphalt and surfaced with mineral granules on the weather side. Glass-fiber mats have been the predominant substrate since the late 1970s, ASTM withdrew D225, the organic shingle specification, in 2012, and the IRC now requires asphalt shingles to meet ASTM D3462, the glass-felt standard.

Oriented strand board (OSB)

A structural wood panel made by pressing thin, rectangular wood strands, laid in layers that cross one another, together with moisture-resistant adhesive under heat. It is widely used as roof sheathing; APA-trademarked panels are stamped with a span rating and exposure durability class, and ARMA gives 7/16-inch exterior-grade OSB as the thinnest wood deck for asphalt roofing unless local code asks for more.

OSHA Subpart M (fall protection)

The federal construction fall protection standard, 29 CFR 1926.500 through 1926.503: definitions, where protection is required, criteria for guardrails, safety nets, personal fall arrest, warning lines and safety monitors, and training. For roofing, protection is required at unprotected sides and edges 6 feet or more above a lower level.

Overdriven (and underdriven) nail

A shingle nail driven so hard that its head cuts into or breaks through the shingle; an underdriven nail is one left standing above the surface. ARMA's fix for an overdriven or crooked nail is to remove it, seal the hole with asphalt roof cement and nail nearby, while an underdriven nail is tapped flush. Poorly adjusted pneumatic nailers are a common cause.

Overflow (secondary) drainage

Emergency drains or scuppers that relieve water from a low-slope roof when the primary drains are clogged or overwhelmed, so water cannot keep building up on the roof. They are a backup to the primary drains, which carry the water in normal conditions.

Overhead and profit (O and P)

The markup a general contractor charges for managing a job, covering supervision, coordination and business costs plus profit, figured as a percentage of the work. On insurance claims it is often argued when several trades are involved; whether and how it is paid depends on the policy, the job and state rules.

Pan-and-cover (two-piece mission) tile

A high-profile tile roof built from two separate half-round pieces: concave pans laid in rows to carry water, and convex covers laid over the joints between them. Also called barrel mission tile, it is made in straight and tapered shapes, and the covers are typically supported on a raised nailer or set in mortar or foam.

Panel edge clip (H-clip)

A small metal clip, commonly called an H-clip, fitted over the edges of adjoining roof sheathing panels between rafters so the panels support each other. The IRC lists clips, blocking or tongue-and-groove edges as edge support, placing one clip midway between supports or two where the span is 48 inches.

Parapet

A low wall extending above the roofline around the perimeter of a flat or low-slope roof, common on commercial buildings. Parapets are capped with metal coping and must be flashed where the roof membrane turns up the wall.

Payment bond

A surety bond that guarantees payment to the people who supply labor or material for the work, such as roofing subcontractors and distributors. Federal construction contracts over 150,000 dollars require one, generally at 100 percent of the contract price and never less than the performance bond.

PBR panel (R-panel)

A ribbed, through-fastened steel panel used for both roofing and siding, sold under the R-panel name and screwed straight through its face to purlins or joists. The PBR version can be ordered with purlin-bearing legs; one maker lists 36 inches of coverage with ribs 12 inches on center and classes it as a structural panel.

Penetration

Any object that passes through the roof surface — a plumbing vent, flue, skylight, or conduit. Each penetration must be flashed and sealed to prevent leaks.

Percentage deductible

A deductible stated as a percentage of the home's insured value rather than a flat dollar amount. On a home insured for 300,000 dollars, a 2 percent deductible means the owner pays the first 6,000 dollars of the covered loss. Percentage deductibles are common for wind and hurricane damage.

Performance bond

A surety bond guaranteeing that the contractor will carry out its contract; if the contractor defaults, the surety answers for the owner's loss up to the bond amount. Federal law generally requires one on construction contracts over 150,000 dollars, normally equal to 100 percent of the contract price.

Perlite roof board

A rigid board made from perlite, volcanic glass expanded by heat into small glassy cellular particles, formed as single-layer or multilayer panels. ASTM C728 classifies Type 1 as roof insulation board and Type 2 as cover or recover board, for use above roof decks beneath built-up, modified bitumen and elastomeric membranes.

Perm (permeance)

The unit for how readily water vapor passes through a material or assembly: grains of vapor per hour per square foot per inch of mercury of vapor pressure difference. Lower numbers mean tighter vapor control; by the ASTM E96 desiccant method a Class I vapor retarder is 0.1 perm or less. Permeability states the same property per unit thickness, in perm-inches.

Permit expiration

The point at which a building permit lapses. Under the model residential code a permit becomes invalid if work does not begin within 180 days of issue or if more than 180 days pass between inspections once work starts, though the building official may grant written extensions for cause.

Personal fall arrest system (PFAS)

Equipment that stops a worker who has already fallen: an anchorage, connectors and a full-body harness, usually with a shock-absorbing lanyard or self-retracting lifeline. OSHA requires it be rigged so the worker can neither free fall more than 6 feet nor strike a lower level, and body belts have been barred for fall arrest since January 1, 1998.

Photovoltaic (solar) shingles

Roofing units that generate solar electricity while serving as the roof covering itself, rather than panels carried on racks above it. IRC R905.16 allows them only on slopes of 2:12 or steeper over a solid or closely fitted deck with code underlayment and ice barrier, requires listing to UL 7103 or to both parts of UL 61730, and assigns a UL 7103 wind class by design wind speed.

Pipe boot (vent flashing)

The flashing that seals around a plumbing vent pipe, typically a metal or plastic base with a rubber collar. The collar degrades under ultraviolet exposure — quickly at Colorado altitude — and cracked pipe boots are among the most common sources of small roof leaks.

Pitch factor (slope factor)

A multiplier that converts a roof's flat plan area, such as one scaled from a drawing, into its true sloped area. It rises with steepness, about 1.054 at 4:12, 1.118 at 6:12 and 1.202 at 8:12, so steeper roofs need noticeably more material than their footprint suggests.

Pitch gauge (slope locator)

A hand tool laid on the roof surface or a rafter to read slope directly, typically showing degrees on one scale and inches of rise per foot on another. Roofers use it to confirm pitch for product limits, steep-roof charges and safety planning; a rafter square and a level can do the same job.

Pitch pocket (pitch pan)

An open-bottomed, flanged enclosure placed around an odd-shaped roof penetration, such as a steel support or a bundle of conduit, stripped into the membrane and filled with grout and pourable sealer. Molded plastic sealant pockets are a common prefabricated alternative to site-formed metal pans.

Plasticizer migration

The gradual loss of the plasticizing chemicals that keep some thermoplastic membranes, notably PVC, flexible. As the plasticizer leaves the sheet over time, the membrane loses flexibility, shrinks and becomes brittle.

Plywood sheathing (CDX)

A structural panel glued up from thin wood veneers, with the grain of each layer running across the layer beneath it. Roof decks use rated sheathing grades; the familiar CDX panel belongs to the Exposure 1 bond class, built to ride out construction-time wetting but not to stay outdoors permanently, and ARMA puts the minimum plywood deck for asphalt roofing at 15/32 inch exterior grade.

Polyisocyanurate (polyiso) insulation

Rigid closed-cell foam insulation board faced on both sides, usually with coated glass or felt facers, and widely used above the deck under low-slope membranes. ASTM C1289 is the product specification, covering faced boards intended for service temperatures from minus 40 to 200 degrees F. Its thermal resistance declines somewhat with age as the blowing agent diffuses out, which is what LTTR values account for.

Polymer roof tile (synthetic slate and shake)

A roof tile made from a polymer-based formulation to look like natural slate or cedar shake. Code compliance can be shown through an ICC-ES evaluation report; one based on the AC07 criteria for special roofing systems rates a polymer shake and slate line Class A or Class C for fire depending on the assembly and sets its underlayment, fasteners and maximum exposure.

Polystyrene insulation (EPS and XPS)

Rigid foam boards made either by molding expanded polystyrene beads (EPS) or by extruding foaming resin into a board with a tight skin on each face (XPS). ASTM C578 defines their types and properties. Polystyrene softens under heat, so it calls for a cover board beneath hot-applied bitumen and a protective disc under induction-welded plates.

Ponding water

Water that remains on a low-slope roof more than about 48 hours after precipitation ends — the benchmark commonly used in the industry. Persistent ponding accelerates membrane aging, can void warranties, and usually signals inadequate slope or blocked drains and scuppers.

Positive drainage

A design condition in which the deck deflection under all expected loads has been accounted for and enough extra slope added that the roof drains completely within 48 hours after rain in weather conditions that allow drying. It is the design target that prevents the ponding water that shortens membrane life.

Preliminary notice

A notice some states require subcontractors and suppliers to send the property owner early in a job to preserve their right to file a mechanics lien if unpaid. Rules differ by state; in California, for example, it is due within 20 days of starting work or delivering materials, and lateness limits what the lien can cover.

Preservative-treated cedar

Cedar shakes or shingles pressure-impregnated with a wood preservative at a treating plant, recommended for high-humidity regions, low-slope applications and shakes laid directly on a solid deck. Treated product takes Type 316 stainless steel fasteners, and the treating company sets its warranty and says whether stains or cleaners may be used; it is a different treatment from fire-retardant cedar.

Prompt rescue (fall rescue plan)

OSHA 1926.502(d)(20) requires an employer whose crew uses personal fall arrest to arrange prompt rescue of anyone who falls, or to make sure workers can get themselves to safety. Rescue therefore has to be planned before work begins: how a worker left hanging in a harness below the eave will be reached and brought down.

Prompt-payment deadlines

State time limits on how fast insurers must handle a claim. In Texas an insurer generally has 15 days to acknowledge a claim, 15 business days after receiving what it needs to accept or deny it, and five business days after agreeing to pay to send payment, with longer periods after major disasters.

Proof of loss

A formal statement from the policyholder to the insurer describing a loss and the amount claimed, which the insurer uses to determine the extent of its liability. Whether one is required, and its deadline and form, are set by the policy and state law.

Property claim mediation

An informal, nonbinding settlement conference led by a neutral mediator, offered as an alternative to appraisal or a lawsuit when a policyholder and insurer disagree. In Florida's state program the insurer pays the mediation cost, and a policyholder who signs a settlement there may rescind it within 3 business days unless the check has been cashed.

Prorated Warranty

A warranty whose payout for a covered defect shrinks as the roof ages, deducting for the years of use already received. Most manufacturer material warranties become prorated after an initial non-prorated period, so a "lifetime" roof may pay only a depreciated fraction of replacement cost later in its life.

Protected membrane roof (PMR)

An inverted roof assembly in which the insulation is laid on top of the waterproof membrane rather than beneath it, then held down with ballast or pavers. Because water reaches the membrane by passing through and under the insulation, these assemblies often include a drainage course that lets it move sideways to the drains.

Public adjuster

A claims professional hired by the policyholder, not the insurer, to prepare and negotiate a property claim, usually paid a percentage of the settlement. Licensing and fee rules vary by state; Texas, for example, requires public adjusters to hold a license from its Department of Insurance.

Purlin

A horizontal member installed under a run of rafters partway up the slope to shorten their span. The IRC requires a purlin to be continuous and at least as large as the rafters it supports, held up by 2 by 4 braces running to bearing walls at 45 degrees or steeper, spaced no more than 4 feet apart and with no more than 8 feet of unbraced length.

PVC membrane

A thermoplastic single-ply sheet made from polyvinyl chloride resin, compounded with plasticizers so it stays flexible, and reinforced with fibers or fabric. Laps are heat welded. ASTM D4434 sets the minimum sheet properties, but like other membrane standards it leaves uplift resistance and material compatibility to the design of the whole roof system.

PVDF (Kynar 500)

A premium metal-roof paint system based on polyvinylidene fluoride resin, widely sold under the Kynar 500 trade name. Its strong carbon-fluorine bonds resist UV fade and chalking, holding color for decades, which makes it well suited to Colorado's intense high-altitude sun.

R-value (thermal resistance)

A measure of how strongly a material resists heat flow, stated in the US in hour-square foot-degree F per Btu; the higher the number, the better it insulates. The IRC requires insulation R-values to be determined under the Federal Trade Commission rule at 16 CFR Part 460, at a mean temperature of 75 degrees F.

Racking

Installing shingles in a vertical column straight up the roof, then filling across, instead of the standard stepped diagonal method in which each course starts a set offset along from the one below. It is fast, but some manufacturers restrict or prohibit it because it tends to leave nails out at shingle ends and can produce repeating visible patterns.

Radiant barrier

A sheet of aluminum foil or metallized film, alone or laminated to a backing, with at least one surface whose far-infrared emittance is 0.1 or less, installed in an attic to cut radiant heat transfer from the hot roof deck. Its low-emittance face must border an air space to work; ASTM C1313 is the material specification.

Rafter

One of the sloped framing members running from the ridge or a hip down to the eave that carry the roof deck. Under the IRC, rafters are sized from span tables with spans measured on the horizontal projection, and each end needs at least 1 1/2 inches of bearing on wood or metal, or 3 inches on masonry or concrete.

Rafter tie

A horizontal member tying opposing rafters together in the lower part of the roof so the outward thrust of the rafters is not carried by the walls. Ceiling joists running parallel to the rafters often do this job; where they do not, the IRC calls for rafter ties at least 2 by 4 inches nominal, no more than 24 inches on center, or a ridge designed as a beam.

Rafter vent (insulation baffle)

A channel fitted between rafters or trusses at the eaves that holds attic insulation away from the underside of the deck, keeping an open airway from the soffit vents into the attic. IRC Section R806.3 requires at least a 1-inch space between insulation and roof sheathing at the vent location.

Raised-heel (energy-heel) truss

A roof truss built like a standard one except that its end, or heel, is raised above the top of the exterior wall, leaving room for full-depth attic insulation over the wall plate without crushing it and making attic ventilation simpler. The IRC rewards the extra depth: where uncompressed R-38 runs at full height over the wall top plate at the eaves, R-38 over the whole ceiling satisfies an R-49 requirement, and R-49 installed the same way satisfies R-60.

Rake

The inclined edge of a roof over a gable end, running from eave to ridge. Rake edges receive drip edge and starter courses to resist wind uplift.

Rapid shutdown (PV)

The National Electrical Code requirement, NEC 690.12, that a rooftop solar system can be de-energized quickly so firefighters working on or near the array are not exposed to dangerous voltage. Since the 2017 edition, conductors outside the array boundary, set at 1 foot from the array in all directions, must drop to 30 volts or less within 30 seconds, and from January 1, 2019 those inside it to 80 volts or less, which pushed installers toward module-level electronics such as microinverters and optimizers.

Re-cover (overlay)

Installing a new roof covering over the existing one instead of tearing off. Codes allow no more than two layers of asphalt shingles; an overlay costs less up front but hides the deck from inspection, adds weight, and typically shortens the new roof's service life.

Recycled asphalt shingles (RAS)

Old asphalt shingles from tear-offs that are ground and reused, mainly in asphalt paving mixes, instead of going to a landfill. The Construction and Demolition Recycling Association reports more than 16 million tons of shingle waste recycled into asphalt roads since 2009, still only a fraction of the shingle waste generated.

Reglet

A groove at least an inch deep, sawn into masonry along a mortar joint or in a straight line parallel to the roof slope, that receives the bent top edge of a counterflashing, which is then sealed in place. It lets the counterflashing be locked into the chimney or wall rather than just fastened to its face. Also called a raggle.

Reinstallation of materials (reroofing)

The IRC reroofing rule on reusing parts of an old roof: sound slate and clay or cement tile may be relaid, but damaged, cracked or broken pieces may not, and aggregate surfacing is never reinstalled. Existing flashings, edgings, outlets and vents that are rusted, damaged or deteriorated must be replaced, and ARMA suggests bending sound chimney cap flashings out of the way during tear-off so they can be reused.

Release film (release tape)

The narrow plastic or paper strip on the back of a self-sealing shingle that lines up with the sealant of the shingle beneath it in the bundle so the stack does not fuse together. It does its job only in the package; on the roof it is simply left in place and does not need to be peeled off.

Reroof load increase trigger (IEBC 706.2)

The IEBC rule requiring any existing gravity-load-carrying member to be strengthened or replaced when roofing or equipment work raises its dead, live or snow load by more than 5 percent. A second roof layer weighing 3 pounds per square foot or less over a single existing layer is exempt, as are small residential buildings built to conventional light-frame or IRC methods.

Reroof mitigation requirements (Florida)

Hurricane retrofits Florida requires when the roof covering of a site-built single-family home is replaced, set by Florida Statutes 553.844 and Section 706.7 of the Florida Building Code, Existing Building: strengthening the roof deck attachment and adding a secondary water barrier, and, for homes in the wind-borne debris region insured or valued at 300,000 dollars or more, improving roof-to-wall connections where that costs no more than 15 percent of the reroof.

Reroofing

The code term covering both ways of putting a new roof on an existing building: a roof recover laid over the old covering, or a roof replacement that strips it first. In the International Residential Code the rules for either route sit together in Section R908, which also says when a recover is not permitted.

Reroofing slope and overflow drain exceptions

Two allowances in the reroofing sections of the IRC (R908.1), IBC (1512.1) and IEBC (705.1): replacing or recovering a low-slope roof that already drains positively does not require building it up to the 1/4:12 (2 percent) minimum design slope for new roofs, and does not require adding secondary overflow drains or scuppers. Under the IBC and IEBC, existing overflow drainage may not be removed unless it is replaced.

Respirable crystalline silica

Very fine dust released when materials such as concrete, stone, brick and mortar are sawn, ground or drilled, as when concrete roof tile is cut; breathing it can cause silicosis, an incurable lung disease, and lung cancer. OSHA's construction standard, 29 CFR 1926.1153, caps exposure at 50 micrograms per cubic meter averaged over 8 hours, and its Table 1 lists accepted controls such as a handheld saw that feeds water to the blade.

Retainage

A portion of each progress payment held back by the owner until the work is finished and accepted, as security that the job will be completed properly. The percentage is set by contract and sometimes limited by law; on federal construction contracts, for example, it may not exceed 10 percent.

Ridge

The horizontal line at the top of a roof where two sloping planes meet. It is capped with ridge shingles or ridge caps and is frequently the location of a ridge vent.

Ridge board (and ridge beam)

The board at the peak of a rafter-framed roof that the upper ends of opposing rafters are nailed against. The IRC requires it to be at least 1 inch nominal thick and at least as deep as the rafters' cut ends; where neither ceiling joists nor rafter ties tie the structure together, the ridge must instead be an engineered ridge beam carried on a wall or column at both ends.

Ridge vent

An exhaust vent installed along the ridge that lets warm, moist attic air escape. Paired with intake vents at the soffit or eave, it drives passive attic ventilation, reducing heat and moisture buildup. See ridge vent and the alternative, box and turtle vents.

Right of Rescission

A homeowner's statutory right to cancel a contract within a set window. Under Colorado's C.R.S. 6-22-104, a property owner may rescind a residential roofing contract within 72 hours of receiving written notice that an insurance claim was denied in whole or in part.

Risk category

The IBC ranking of a building by the danger to people if it fails: I for low-hazard structures such as farm buildings, II for ordinary buildings, III for substantial-hazard buildings such as large assembly spaces, and IV for essential facilities such as fire stations and hospitals with emergency care. The IBC maps basic design wind speeds separately for each category in Section 1609.3, so the category changes the wind speed a roof is designed for.

Roof age rule (Florida insurance)

Florida bars insurers from refusing to write or renew a homeowners policy solely because the roof is under 15 years old. For an older roof the owner may pay for an inspection by an authorized inspector, and a roof found to have 5 or more years of useful life left cannot be the only reason for refusal; age runs from the last time 100 percent of the roof was replaced.

Roof anchor (anchorage)

The fixed tie-off point a fall arrest lifeline or lanyard connects to. OSHA requires it to hold 5,000 pounds per attached worker, or to be designed by a qualified person with a safety factor of at least two; on a pitched roof it is fastened through the sheathing into a structural member, never to sheathing alone.

Roof assembly

The International Building Code term for the complete system that keeps weather out and resists design loads: the roof covering and the roof deck, plus any underlayment, insulation, thermal barrier or vapor retarder between them. Fire and wind-uplift ratings are earned by a specific tested combination of those layers, not by the membrane alone.

Roof bracket (roof jack)

A steel bracket nailed through the roofing into rafters or trusses to hold a plank across the slope as a foothold or staging platform; adjustable models set a 2x10 plank level at angles such as 30, 45 or 60 degrees. Makers commonly limit spacing to 8 feet, and the nail holes must be sealed when the brackets are removed.

Roof de-icing cable (heat cable)

Electric heating cable fastened along the eaves and run through gutters and downspouts to keep a path open so snowmelt can drain away instead of refreezing into an ice dam. Self-regulating cable is meant to clear ice, not to melt away accumulated snow or stop snow from sliding off, and one maker's design guide warns against installing it under any roof covering or where it would be hidden from view.

Roof deck (sheathing)

The structural surface — usually plywood or OSB on residential roofs — fastened over the rafters or trusses, onto which underlayment and the roof covering are installed. Deteriorated decking is replaced during a reroof.

Roof deductible (Florida)

A separate roof deductible Florida lets insurers add to personal residential policies for roof claims settled at replacement cost, with a premium credit and a right to opt out. Its cap is whichever is smaller: 2 percent of the Coverage A limit, or 50 percent of what a new roof would cost, and it does not apply to hurricane losses, total losses, tree strikes that puncture the deck, or repairs to under half the roof.

Roof diaphragm evaluation at reroofing (high-wind regions)

An IEBC reroof permit requirement where the ultimate design wind speed exceeds 130 mph and roofing is stripped from over 50 percent of the roof diaphragm: the deck, its connections to the framing and the roof-to-wall connections are checked against current wind loads, including uplift, and strengthened or replaced if they cannot resist 75 percent of them. Buildings shown to meet ASCE 7-88 or a later edition are exempt.

Roof drain (primary drainage)

An outlet set into a low-slope roof that collects runoff and directs it off the roof. Drains and scuppers that remove water in normal conditions make up the primary drainage; separate overflow drains or scuppers relieve the roof if the primary system clogs or is overwhelmed.

Roof expansion joint

A structural separation between two parts of a building, carried up through the roof, that lets them move independently as temperature changes and the structure shifts, without damage to the roof or waterproofing. The roofing must be detailed so the membrane spans the gap instead of being torn by it; where no structural joint is needed, an area divider handles movement.

Roof fire classification rule (IRC R902)

The IRC section that decides when a house needs a fire-rated roof covering: Class A, B or C roofing is required wherever state or local law designates it, and wherever the roof edge is less than 3 feet from a lot line, with ratings from ASTM E108 or UL 790 tests. Brick, masonry, exposed concrete, and metal, tile or slate over noncombustible decks are recognized as Class A assemblies.

Roof moss

A non-vascular plant that grows on shaded, damp roof planes, typically north-facing slopes or under trees. Unlike algae it can harm asphalt shingles, lifting and curling their leading edges, raising blow-off risk and holding water that can move sideways under shingles into the deck; pressure washing to remove it strips granules and is not advised.

Roof overhang (rake overhang)

The part of a roof that extends out past the exterior walls, forming the eaves at the bottom edge and the rake overhang at a gable end. At a gable, the IRC does not let wood structural panel sheathing cantilever more than 9 inches beyond the end wall unless gable overhang framing is built to support it.

Roof pitch (slope)

The steepness of a roof, expressed as inches of vertical rise per 12 inches of horizontal run — a 6:12 roof rises 6 inches per foot. Pitch determines which coverings are permitted, whether a roof can be safely walked, and pricing: estimates commonly add steep charges at 7:12 and above.

Roof rake (snow rake)

A long-handled rake for pulling snow off a roof so less snow is left to melt and feed an ice dam. University of Minnesota Extension notes that raking or brooming can damage roofing, and that cutting channels through an existing dam only drains trapped water temporarily; the lasting fix is air sealing and insulation that keep attic heat out of the roof.

Roof repair (code term)

The International Residential Code defines roof repair as reconstructing or renewing any part of an existing roof for its maintenance. Whether a repair needs a permit, and how large it can be before it counts as a reroof, is set by each jurisdiction, so the same patch may be permit-free in one city and permitted in the next.

Roof replacement (code term)

As the International Residential Code defines it, taking off the old roof covering, fixing any damaged substrate beneath it, and putting on a new covering. It is the tear-off side of reroofing, as opposed to a recover over the old layer, and exposes the deck so damaged sheathing can be found and fixed.

Roof replacement insulation rule (IECC C503.2.1)

Under the 2021 International Energy Conservation Code, replacing a commercial roof whose insulation lies entirely above the deck and forms part of the thermal envelope brings that roof under the current insulation requirements, and the work may never lower its R-value. A roof recover is exempt as long as building energy use does not rise, and neither route has to add an air barrier when the rest of the envelope is left alone.

Roof truss

A prefabricated roof frame of lumber members arranged in triangles, usually joined with metal connector plates, that spans between walls and carries both the roof and the ceiling. The IRC requires truss design drawings to be approved before installation and delivered with the trusses, and bars cutting, notching, drilling or otherwise altering any truss member without a registered design professional's approval.

Roof-claim solicitation rules (Florida)

Florida law forbids contractors from offering gifts, cash, deductible waivers or anything of value in exchange for a roof inspection or a roof insurance claim, and requires ads urging roof claims to warn about deductibles and fraud. Fines reach 10,000 dollars per violation, and a roof contract signed within 180 days of a declared state of emergency can be canceled within 10 days or by the official start date.

Roofing Application Standard (RAS)

An installation standard in Florida's Test Protocols for the High-Velocity Hurricane Zone, published alongside the Testing Application Standards (TAS) that products are tested to. Each RAS spells out how a roof type is applied, for example RAS 115 for asphalt shingles, RAS 118, 119 and 120 for tile, RAS 128 for low-slope wind design pressures under ASCE 7 and RAS 150 for prescriptive built-up roofs.

Roofing asphalt types (ASTM D312)

The four grades of hot roofing asphalt defined by ASTM D312, known in the trade by name: Type I dead-level, Type II flat, Type III steep and Type IV special steep. Each is a petroleum asphalt refined to its own set of properties, and NRCA gives all four one rule for equiviscous temperature: the point where viscosity reaches 125 centipoise for mop application, or 75 centipoise for a mechanical spreader.

Rooftop curb

A raised frame mounted on the roof deck that supports and lifts equipment such as air-handling units, exhaust fans, skylights or hatches above the roof surface. The roof membrane is carried up the sides of the curb as base flashing.

Rooftop structure (IBC 1511)

Any structure built on top of a roof deck, such as a penthouse, tank, cooling tower, spire or mechanical equipment screen, regulated by IBC Section 1511. Penthouses may only house equipment, tanks, elevators, stairways and shafts, enclosed rooftop structures together may cover no more than one-third of the roof, and on buildings other than Type I a penthouse is generally capped at 18 feet tall.

Rooftop-mounted PV system

Solar panels carried on racking above an existing roof covering, as opposed to solar shingles or BIPV panels that form the covering. IRC R324.4 requires the roof to be designed for the added dead load plus snow, the array and supports to resist component and cladding wind loads, every roof penetration to be flashed and sealed, and the system to carry a fire classification under UL 2703 matching what the roof assembly requires.

Root barrier

A layer placed over the waterproofing of a vegetative roof to keep plant roots and rhizomes from growing into and through the membrane. ANSI/SPRI VF-1 requires one whenever the roof covering itself is not resistant to root penetration, and the companion standard ANSI/SPRI VR-1 gives a test procedure for checking that resistance.

Safety monitoring system

A fall protection method for low-slope roofing in which a competent person with no other duties, on the same roof and within talking distance, watches workers and warns them of fall hazards. It is usually paired with a warning line; OSHA allows it alone on roofs 50 feet wide or less, and no mechanical equipment may be used where it is relied on.

Saffir-Simpson Hurricane Wind Scale

The National Hurricane Center's 1 to 5 rating of a hurricane by its maximum sustained wind alone, from Category 1 at 74 to 95 mph to Category 5 at 157 mph or higher; Category 3 and above are major hurricanes. It describes likely wind damage, from harm to roof coverings, siding and gutters at Category 1 to total roof failure at Category 5, but leaves out storm surge, rain flooding and tornadoes.

SBS-modified (rubberized) asphalt

Asphalt modified with styrene-butadiene-styrene polymer to add flexibility and elasticity. SBS modification helps shingles absorb impact and tolerate temperature swings, and is common in impact-resistant (Class 4) products.

Scope of loss

An adjuster's record of the damage found during an inspection: what is damaged, its degree, the quality of materials and the measurements needed to calculate quantities. It is not the estimate itself; prices and calculated quantities are added later when the estimate is written.

Scrim

A woven, nonwoven or knitted fabric of continuous strands embedded in a roofing membrane to give it tear and breaking strength. TPO and PVC sheets are built around a polyester or glass scrim, which is why cut edges of reinforced TPO are sealed so the scrim is not left exposed.

Scupper

An opening through a parapet or roof-edge wall that drains water off a low-slope roof, either straight through the wall or into a conductor head and downspout. Scuppers frequently serve as the code-required overflow drainage for roofs with interior drains.

Sealant strip (self-seal strip)

A band of heat-activated asphalt adhesive applied at the factory to the face or back of an asphalt shingle. Once the sun warms it after installation, it bonds each course to the one below, a major part of a shingle roof's wind resistance. Sealing time varies with temperature, slope and sun, and the shingles are vulnerable to uplift until the bond forms.

Sealed roof deck

A roof deck whose seams between sheathing panels are covered with self-adhering flashing tape before the underlayment is laid. The IRC permits a strip of ASTM D1970 membrane at least 4 inches wide over every deck joint, topped by standard underlayment, as an alternative underlayment method, and IBHS cautions that textured or waxed OSB may need a compatible primer before the tape will bond fully.

Sealing-washer screw

A metal roofing screw fitted with a rubber sealing washer under its head that compresses against the panel to seal the hole. Correct driving matters: an overdriven screw splits or flattens the washer and an underdriven one leaves it loose, and either can leak. Screws hidden under trim or panel legs may instead use a flat pancake head with no washer.

Seam probing

Checking a heat-welded seam after it has fully cooled by drawing a blunt steel probe, often a cotter-pin puller, along the lap edge to find spots where the probe slips in. Any gap marks an unfused area that must be rewelded or patched. Membrane specifications call for probing every heat-welded seam.

Self-adhering membrane

A roof or waterproofing sheet made with a sticky underside so it bonds to the substrate and to itself at the laps with no separate adhesive, hot bitumen or torch. In the roll the adhesive face is covered by a release paper or film that keeps the sheet from sticking to itself in shipping and is removed during installation.

Self-adhering roll roofing

Granule-surfaced, polymer-modified asphalt roll roofing whose sticky underside is exposed by peeling off a release sheet, covered by ASTM D7505 and D7530. ARMA describes one-, two- and three-ply residential systems built from a nailed base sheet, a self-adhering mid-ply and a granule-surfaced cap sheet, advises using one maker's components throughout, and allows a single cap-sheet layer down to 1:12.

Self-retracting lifeline (SRL)

A fall arrest connector that pays out and reels in line from a spring-loaded drum as the worker moves and locks when a fall begins. OSHA 1926.502(d)(12) requires a unit that limits free fall to 2 feet or less to sustain at least 3,000 pounds with the line fully extended, while units that allow a longer free fall must sustain at least 5,000 pounds.

Selvage (19-inch selvage roll roofing)

An edge strip of roll roofing or cap sheet, left without granules or marked with lines, that the next course overlaps. Double-coverage roll roofing is a 36-inch sheet split into a 17-inch exposed band and a 19-inch selvage, so two layers cover the deck throughout; ARMA allows it on slopes down to 1 inch per foot.

Selvage (selvage edge)

The strip along the edge of a roll of cap sheet, roll roofing or similar material that is made differently from the rest of the sheet, often marked with a line, so the next sheet can overlap and seal to it. Standards let the selvage carry only a fine surfacing that will not get in the way of bonding the lap.

Semi-intensive green roof

A vegetative roof that combines extensive and intensive areas in one system, so it can carry the low, hardy plants of the first alongside some of the larger plantings of the second. ANSI/SPRI VF-1 puts semi-intensive systems at roughly 25 to 40 pounds per square foot, between the extensive and intensive weight ranges.

Severe hail

Hail 1 inch in diameter (quarter size) or larger, the size at which the National Weather Service classifies a thunderstorm as severe, alongside wind gusts of 58 mph or more or a tornado. Smaller hail does not make a storm severe, although frequent small-hail storms still add wear to a roof over time.

Shading (shingle color variation)

Patches of a new shingle roof that look lighter or darker as the viewing angle and light change, caused by tiny texture differences from manufacturing rather than by a defect. It shows most on dark single-layer shingles such as three-tabs, has no effect on performance, and is lessened by color blends, installing across and up the roof so bundles mix, and weathering.

Shake interlayment

An 18-inch-wide strip of No. 30 roofing felt laid over the top portion of each course of wood shakes and onto the deck, so it lies between courses. It blocks wind-driven snow and rain and turns water back to the surface; its bottom edge sits above the butt by twice the exposure. Wood shingles are never interlaid with felt.

Sheathing gap

The 1/8-inch space APA recommends at all end and edge joints of plywood or OSB roof sheathing, unless the panel maker says otherwise. Wood panels swell as they take on moisture, and panels butted tight can buckle and ridge the shingles above. A 10d box nail works as a spacing gauge.

Sheathing nailing schedule

How roof sheathing panels are fastened to the framing. APA's baseline is 8d common nails every 6 inches along supported panel ends and edges and every 12 inches at intermediate supports, set about 3/8 inch in from the panel edges, with more fasteners where high winds require them.

Shingle blister

A small raised bubble in an asphalt shingle's surface, usually 1/4 inch across or less, that eventually ruptures to leave a steep-sided pit sometimes reaching the mat. Blisters come from asphalt quality combined with heat, with poor attic ventilation or excess roofing cement as contributors; they are not hail damage, though they are often first noticed after a storm.

Shingle buckling

Wrinkles or ridges running across installed shingles, usually caused by the deck or underlayment moving rather than by the shingle itself. Typical causes are wet or wrinkled felt, sheathing panels installed tight without spacing gaps, and wide board decking that swells and shrinks with moisture.

Shingle fashion

Lapping any roofing layer so each higher piece overlaps the one below it, as shingles do, so water always runs over a joint rather than into it. Underlayment, flashing and roll materials are all installed this way; the IRC uses the phrase for single-layer underlayment laid from the eave upward with 2-inch laps on slopes of 4:12 and steeper.

Shingle nail requirements

Under IRC R905.2.5, asphalt shingles are fastened with galvanized steel, stainless steel, aluminum or copper roofing nails with at least a 12-gage (0.105-inch) shank and a 3/8-inch head, complying with ASTM F1667. Each must reach at least 3/4 inch into the sheathing, or all the way through sheathing thinner than that. The code section lists nails only, not staples.

Shingle offset

The sideways shift between the end joints or cutouts of one course and those of the course above, set in each product's instructions. Three-tab shingles commonly step 6 inches per course, while laminated shingles use their own offsets, sometimes varied from course to course. Wrong offsets can stack joints and leave visible diagonal or zigzag patterns.

Shingle overhang (eaves and rakes)

How far the starter course and field shingles project beyond the roof edge metal. ARMA calls for roughly 1/4 to 3/4 inch past a plain 90-degree drip edge; with its recommended drip edge profile, eave shingles may sit flush or overhang up to 3/4 inch and rake shingles may be trimmed flush. Without any drip edge, it suggests overhangs of 3/8 to 1 inch at eaves and rakes.

Side clip (hurricane clip)

A clip for roof tile with a side interlock that holds the edge of the tile so wind uplift cannot twist it out of position. Also called a hurricane clip, it is one of several tile clips, along with nose, eave and field clips, that tested attachment methods combine with nails or screws.

Side lap (underlayment)

The overlap along the long edge of a course of underlayment, where each higher course covers the top of the one below it. Under the IRC, a single layer on slopes of 4:12 and steeper laps 2 inches, while the double layer required from 2:12 up to 4:12 laps each 36-inch sheet 19 inches over the last. Where two rolls meet end to end within a course, the overlap is an end lap instead.

Silicone roof coating

A solvent-borne liquid elastomeric coating whose main polymer is more than 95 percent silicone. ASTM D6694 covers it as the weathering membrane over spray polyurethane foam, with limits for the cured film on elongation, tensile and tear strength, permeance, adhesion, and flexibility in the cold after accelerated weathering.

Single-lock and double-lock seams

The two ways a mechanically seamed metal panel can be folded closed. A single lock folds the seam once, about 90 degrees; a double lock folds it twice, about 180 degrees, for greater strength and water resistance. Engineered systems usually specify the double lock, while a single lock is easier to open when a damaged panel has to be replaced.

Single-ply membrane

A low-slope roofing sheet installed in large panels and seamed together — TPO, PVC (both thermoplastic, heat-weldable) or EPDM (a synthetic rubber). Common on flat commercial and some residential roofs.

Six-nail pattern (high-wind nailing)

Fastening each strip shingle with six nails instead of four, often called storm or high-wind nailing. Manufacturers publish it as an option for windy areas and generally require six or more nails plus hand-sealing on slopes steeper than 21:12; local codes may also require it, so check both before quoting a job.

Skylight fall protection

OSHA counts a skylight as a hole in the walking surface and requires workers to be protected from falling through one more than 6 feet above a lower level by a cover, a guardrail around it, or a personal fall arrest system, and from stepping into it by a cover. It applies during roofing work around existing skylights.

Slate grades S1, S2 and S3 (ASTM C406)

The three grades of roofing slate in ASTM C406, assigned by laboratory tests of breaking strength, water absorption and depth of softening. S1 is the most weather-resistant grade and S3 the least. Slates with soft carbonaceous ribbons are excluded from the standard.

Slate headlap

The distance by which each slate is overlapped by the slate two courses above it, the zone where the roof is three layers thick. The customary headlap is 3 inches, reduced on very steep or mansard slopes and increased on low slopes; the exposure of each course is the slate length minus the headlap, divided by two.

Slate hook

A small metal hook, often stainless steel, that holds a slate by its bottom edge rather than by nails through its face. Hooks are used to secure replacement slates during repairs and, in hook-fix systems, to hang every slate from a strip or hook fastened to the deck, leaving no nail holes in the stone.

Slate ripper

A slater's tool that is slid up beneath an installed slate to hook and cut or pull out the nails holding it, the first step in removing a broken slate for replacement. Where a roof was laid with steel cut nails rather than copper, ripping can loosen or damage neighboring slates, which then need repair as well.

Slating nails

Nails used to hang roofing slate, which should be non-ferrous, such as solid copper or stainless steel, since plain steel and galvanized nails rust out long before sound slate wears out. They are not driven tight: each slate should hang freely on its nails, because an overdriven nail cracks the slate and a proud head punctures the one lapping over it.

Sliding (expansion) clip

A two-piece standing-seam clip whose base is fastened down while an upper tab, locked into the seam, can slide along it, so the panel can grow and shrink with temperature. Also called an expansion, slider or floating clip, it is typical of long mechanically seamed runs, and the panel it serves must be pinned at one point so it moves in a controlled direction.

Slip sheet (separator sheet)

A thin layer such as kraft paper, polyester scrim or polyethylene placed between two parts of a roof assembly so they cannot bond to each other. It also keeps chemically incompatible materials apart and protects the membrane from abrasion against the layer below.

Slope transition (pitch change)

A line where a roof plane changes pitch, such as the break between the two slopes of a gambrel roof or the joint where a lower-pitched porch roof meets a steeper main roof. The IRC requires flashing wherever the roof changes slope or direction, and ARMA lists slope transitions among the critical areas where self-adhering underlayment is commonly installed.

Smart Choice Protection Period

GAF's term for the initial, non-prorated window of its shingle warranty, typically the first 10 years, during which covered manufacturing defects are fully covered and the warranty transfers with full benefits. After it ends, remedies are prorated to reflect the use received from the product.

SMP (silicone-modified polyester)

A lower-cost metal-roof paint system that offers moderate fade and chalk resistance. It performs acceptably but weathers faster than PVDF, especially in vivid colors, and typically carries shorter finish warranties.

Snap-lock panel

A standing-seam metal panel whose male leg is held to the deck by concealed clips and fasteners, after which the female leg of the next panel snaps over it by hand, with no seaming tool. It is quicker to install than a mechanically seamed panel but relies on water shedding quickly, so it is generally not used on roofs of about 3:12 slope or lower.

Soffit

The underside of a roof overhang, spanning from the fascia back to the wall. Vented soffits provide the intake air for attic ventilation.

Soil stack (plumbing vent stack)

The plumbing vent pipe that runs up through the roof to vent the plumbing fixtures below, one of the most common roof penetrations. ARMA's detail fits a cut shingle over the pipe, sets a preformed boot in asphalt roof cement, laps the side and upper shingles over its flange, keeps nails at least 2 inches from the pipe, and calls for checking the flange for cracks once a year.

Solar access pathway (fire setback)

A clear strip left free of solar panels so firefighters can reach, ventilate and escape a roof. IRC R324.6.1 requires at least two pathways at least 36 inches wide on separate roof planes, running from the lowest edge to the ridge, with at least one on the street or driveway side and one serving each plane that holds an array; roofs of 2:12 slope or less are exempt.

Solar reflectance (albedo)

The fraction of incoming sunlight a surface reflects, rated from 0 to 1 (0 to 100 percent). It is the main property that makes a roof cool, and it can be measured in the lab or on the roof, for example under ASTM C1549 with a portable solar reflectometer.

Solar Reflectance Index (SRI)

A single number, calculated under ASTM E1980 from a surface's solar reflectance and thermal emittance, that rates how cool it stays in sunlight against a standard black (0) and a standard white (100). Very hot materials can score below zero and very cool ones above 100; California's Title 24 energy code uses aged SRI values.

Solar ridge setback

The clear band a rooftop solar array must leave on each side of a horizontal ridge for firefighter access and smoke venting. Under IRC R324.6.2 it is at least 18 inches when the array covers 33 percent or less of the plan-view roof area and 36 inches when it covers more; homes with a qualifying automatic sprinkler system may use the higher 66 percent threshold in R324.6.2.1.

Solvent welding

A seaming method in which a liquid solvent is applied to the overlapping sheets of certain membranes, most of them thermoplastic, softening the surfaces chemically so the two layers fuse into one. It is the chemical counterpart of heat welding, which fuses the same kind of lap using hot air and pressure.

Spaced sheathing (skip sheathing)

Roof sheathing of boards, at least 1 by 4 inches, nailed across the rafters with gaps between them, traditionally used under wood shakes and shingles so air can reach their undersides and they can dry. Also called strapping or open lath; solid sheathing is used instead where wind-driven snow, seismic rules or treated shakes call for it.

Span rating

The two numbers stamped on APA-rated sheathing, such as 24/16 or 32/16. The left number is the maximum spacing in inches of roof supports the panel may span; the right is the maximum floor joist spacing. The IRC's sheathing table pairs each rating with a minimum thickness and says when the panel edges need support.

Spangle

The crystalline pattern that develops on the surface of hot-dip metallic-coated steel, such as galvanized sheet, as the molten coating metal cools and solidifies. It is part of the metallic coating itself, formed as the coating froze, rather than a paint finish or a surface stain.

Spanish tile (S-tile)

A one-piece interlocking roof tile that combines a rounded barrel and a flat or nearly flat pan, giving a laid roof a low, rolling profile. A raised lip along the flat edge engages the barrel edge of the neighboring tile, they are typically nailed through two holes at the top, and the English call the same shape a single Roman tile. Two-piece mission tile is a different system.

Special purpose wood roof (IBC 1505.7)

A wood shake or shingle roof built over a layer of 5/8-inch Type X gypsum board or gypsum sheathing, laid beneath the 1/2-inch solid wood panel sheathing or 1-inch spaced sheathing for added fire protection. The IBC allows Number 1 grade cedar or redwood shakes and shingles built this way on buildings of no more than two stories and 6,000 square feet of roof area with 10 feet of fire separation to lot lines.

SPF surface texture (orange peel to popcorn)

The graded roughness of a sprayed foam roof, which decides whether it can take its protective coating. Orange peel and coarse orange peel are acceptable; verge of popcorn is the roughest texture still accepted, though it consumes extra coating; popcorn, with sharp-angled valleys between the nodules, is rejected as a base for coating.

Splice tape (seam tape)

A cured or uncured synthetic rubber tape used to join overlapping sheets of rubber membrane, most commonly EPDM. The lap is cleaned and primed before the tape is applied, because the primer is what lets the tape develop full peel and shear strength at the seam.

Spray polyurethane foam (SPF) roofing

A roof built by spraying two liquid components, an isocyanate (the A side) and a polyol-based resin (the B side), which react on contact and expand into a rigid foam that bonds fully to the surface below, insulating and waterproofing in one layer. The foam is then covered with a protective elastomeric coating, and core cuts are used to check foam and coating thickness and adhesion.

Spread of flame test (ASTM E108 / UL 790)

The part of the roof covering fire test that measures how far flame travels over the surface. A gas flame and an air current are applied to the test deck, for ten minutes in Class A and B tests and four minutes in Class C, and FM Approvals limits the spread to 72 inches for Class A, 96 inches for Class B and 156 inches for Class C, with no excessive sideways spread.

Square

The roofing unit of area equal to 100 square feet (a 10 ft x 10 ft area). Roofs are estimated, sold, and installed by the square — a "20-square roof" covers 2,000 square feet of roof surface.

Stack effect

The pressure difference that builds when warm indoor air, lighter than cold outdoor air, rises through a building, pushing air out through leaks near the top and pulling it in near the bottom. It grows with building height and colder weather, and in a heated house it drives warm, moist air through ceiling leaks into the attic.

Standing-seam clip

A concealed metal anchor fastened to the deck or framing that engages the edge of a standing-seam panel and holds it down without any screw passing through the panel face. Besides resisting wind uplift, its main job is to let the panel change length with temperature without fatiguing the attachment. Clips are also called cleats, especially in wall and copper work.

Standing-seam metal roof

A metal panel system whose panels join at raised, interlocking seams with concealed fasteners, so no screw heads penetrate the weather surface. It outlasts exposed-fastener metal roofing and sheds snow well, though the flat pan areas can exhibit oil-canning.

Starter strip

The first course of shingles (or a purpose-made starter product) installed at the eave and rake. Its adhesive bonds the first exposed course and improves wind resistance at the roof's edges.

Steep-slope roofing

Roofing on pitches of roughly 3:12 and greater, where water sheds by gravity. Shingles, tile, slate, and metal panels are steep-slope systems. Contrast with low-slope roofing.

Step flashing

Individual L-shaped metal pieces woven into each shingle course where a roof plane meets a sidewall, such as along a dormer or the side of a chimney. Each piece laps over the one below so water steps down the wall and back onto the roof surface.

Stitch (lap) screw

A short self-drilling screw that fastens two overlapping metal panels to each other at the side lap, rather than fastening a panel down to the framing. On exposed-fastener roofs stitch screws are usually driven through the crown of the lapped rib at roughly 12 to 24 inches on center to keep the lap tight.

Stone-coated steel roofing

Metal roofing pressed from aluminum-zinc coated steel into shingle, shake or tile shapes, then finished with an acrylic resin coat, a layer of pigmented stone granules and a clear acrylic overglaze. The result is a lightweight steel roof with the textured look of a traditional one.

Storm Chaser

A transient roofing or construction company that follows severe weather across the country and solicits homeowners in hail- or wind-damaged neighborhoods, often within days of a storm, using high-pressure tactics and lacking a verifiable local presence.

Storm collar

A metal band clamped around a factory-built metal chimney just above its roof flashing cone and sealed to the pipe with mastic, shielding the top of the cone from rain. On one major chimney maker's flashing, the cone has ventilation slots that the collar shelters and that must not be sealed, and the flashing base goes under the roofing at the top and sides but over it at the bottom.

Straight-line winds

Damaging thunderstorm winds that are not rotating, a label used mainly to separate them from tornado winds. Downbursts and derechos cause straight-line wind damage, which tends to lay trees and debris down in one general direction along a fairly straight path.

Straight-split shake

A cedar shake split from the same end of the block every time, by machine or by hand, so it has the same thickness from butt to tip rather than a taper. It is made only in premium grade, meaning all edge grain, and is laid with its smoother froe end, where the split started, toward the ridge.

Striations (stiffening ribs)

Shallow lines or small ribs rolled into the flat pan of a metal panel between its seams. Also called pencil ribs or stiffening ribs, they break up the flat surface and add stiffness, which does not stop oil-canning but makes any waviness much less noticeable.

Strip flashing (stripping in)

Strips of membrane laid over the flange of a metal flashing, such as edge metal or a drain or vent flange, to seal that flange into the roof membrane around it. Putting these plies down is called stripping in, and the strips themselves are often called stripping plies.

Strip shingle

An asphalt shingle roughly three times as long as it is wide, such as the traditional 12-by-36-inch format, installed in overlapping horizontal courses. Three-tab, laminated and no-cutout shingles are all strip shingles, as opposed to individual, interlocking or hexagonal shingles.

Strippable film (protective film)

A thin, removable plastic film applied over the painted face of prefinished coil, sheet or formed panels so the finish is not scratched during fabrication, shipping and installation. Heat and sunlight bond it to the paint, so it has to come off as each piece is installed; one maker warns that film left in the sun past the end of the day may be almost impossible to remove.

Structural metal panel

A metal roof panel built to span open framing, such as purlins or joists, instead of needing a solid or closely spaced deck beneath it. It is the counterpart of the architectural panel, and some through-fastened structural profiles are rated by their makers for slopes as low as one-half inch per foot.

Supplement (insurance)

A request to the insurer for additional payment on an approved claim, covering items the original estimate missed or underpriced — code-required drip edge or ice-and-water shield, rotted decking, steep- or high-roof charges. Supplements are routine on hail claims and are documented with photos, invoices, and code citations.

System Warranty

An enhanced manufacturer warranty available only when a certified contractor installs a complete matching set of that manufacturer's components (shingles plus required accessories). Examples include GAF Golden Pledge, Owens Corning Platinum Protection, and CertainTeed SureStart PLUS, which add long, manufacturer-backed workmanship coverage beyond the basic product warranty.

T-joint cover

A small, typically round, molded membrane patch welded over a T-joint, the spot where three or four sheets overlap and the upper sheet steps over the edge of a lap below. The step-off at that spot is hard to weld watertight, so the cover seals it. At least one major manufacturer requires the cover on all of its TPO sheets 60 mil and thicker.

Tapered cricket (low-slope saddle)

On a low-slope roof, a small sloped area built from tapered insulation, often shaped like a diamond or a flattened pyramid, placed on the high side of a curb or wall, or in the valley between two drains, to steer water toward the outlets instead of letting it sit. On steep roofs the term usually means the chimney cricket.

Tapered edge strip

A factory-cut strip of rigid insulation or fiberboard that slopes from zero thickness on one edge to about 1/2 to 2 inches on the other. It provides a smooth transition where insulation changes height, such as at a roof edge, around a drain, or where two roof areas of different thickness meet.

Tapered insulation

Insulation boards manufactured with the slope built into them, or a poured lightweight fill, assembled on a flat structural deck to create slope toward drains, scuppers or gutters before the membrane goes on. A tapered system is a common way to correct ponding on a dead-flat roof during reroofing, since the structure itself cannot be re-pitched.

Tapersawn shake

A cedar shake sawn on both faces like a shingle but cut thicker, commonly 5/8 or 3/4 inch at the butt, giving a heavy shadow line with a tailored look. It is installed as a shake, with felt interlayment between courses.

Tapersplit shake

A cedar shake split by hand with a steel froe and a mallet, turning the block end for end between splits so each shake comes off with a natural taper, thick at the butt and thin at the tip, much like a shingle. The Cedar Shake and Shingle Bureau lists it only in premium grade, which is 100 percent edge grain.

TAS 100

A Florida Testing Application Standard, part of the Test Protocols for the High-Velocity Hurricane Zone, titled Test Procedure for Wind and Wind Driven Rain Resistance of Discontinuous Roof Systems. Roofing makers cite it on product data for wind-driven rain resistance; companion TAS 100(A) covers ridge and soffit ventilation products.

TDI product evaluation

A report used in the Texas windstorm inspection program to show that a building product meets the building specifications TDI has adopted and how it must be installed to resist wind loads. TDI writes some evaluations itself and links to third-party reports without endorsing the products, and inspectors and engineers use them when certifying construction for Texas Windstorm Insurance Association eligibility.

Tear-off

Removal of the existing roof covering (and often underlayment) down to the deck before installing a new roof. A full tear-off, versus re-covering over the old roof, is required by some codes and lets the deck be inspected.

Telegraphing

Distortion that shows through a new shingle roof because of something uneven beneath it, such as an old shingle layer, lumps in the deck, or wrinkled underlayment. It is a common complaint on recovers and on jobs where felt got wet and wrinkled before the shingles went on.

Temporary repairs (mitigation)

Emergency steps such as tarping a damaged roof to prevent further damage after a loss. Owners are generally expected to take reasonable protective steps, and insurers typically reimburse the reasonable cost of them when receipts are kept, though terms depend on the policy.

Tension leveling

A mill process that stretches metal coil beyond its yield point so it stays flat instead of creeping back to its original uneven shape. Ordering tension-leveled coil, leveled after it has been slit, is one of the main ways panel makers reduce the stress-related waviness known as oil-canning, though nothing prevents it entirely.

Termination bar

A flat bar, usually pre-punched extruded aluminum, screwed through the top edge of a membrane flashing to hold it tight against a wall or curb. Many bars include a ledge that holds a bead of sealant above the fasteners, and the bar is often covered by metal counterflashing for long-term weather protection.

Terne (terne metal)

Sheet iron or steel coated with a lead and tin alloy, a traditional roofing and flashing metal with a duller finish than tin plate that had to be painted periodically. That lead-based product is no longer made, and the name now refers to steel coated with a zinc and tin alloy; terne-coated stainless steel is a restoration substitute that does not corrode if left unpainted.

Test square

A 10-by-10-foot area (one square) that a hail adjuster chalks off on each roof slope to count qualifying hail strikes during an inspection. The number of hits per test square is a common yardstick insurers use when deciding between repair and full replacement.

Textural slate roof

A slate roof that mixes slates of different thicknesses, with rougher faces and uneven tails than standard slate, for an irregular, heavily textured surface. It is most often seen on Tudor-style buildings, sometimes with slates of several colors blended in.

Thermal barrier (torch-applied roofing)

A layer placed over a combustible deck or insulation before a membrane is torched, as a fire-safety measure so the flame cannot reach material that would burn. NRCA accepts perlite board, or board of fiberglass or mineral wool, when at least 3/4 inch thick, or glass-faced gypsum board at least 1/4 inch thick.

Thermal bridging

Heat flow that bypasses insulation through more conductive paths, such as rafters, trusses and the shallow truss heels at the eaves where insulation is squeezed thin. It lowers a roof's installed R-value below the label value and creates warm spots that melt snow, and ventilation alone cannot practically make up for it.

Thermal cycling (metal roofing)

The constant lengthening and shortening of metal roof panels as their surface temperature rises and falls with sun, clouds, rain and night cooling. Panel temperatures can swing well over 100 degrees F in a day, so attachment has to allow the movement; restraining it can cause oil-canning, noise, slotted screw holes and fasteners that back out.

Thermal emittance

How efficiently a surface releases the heat it has absorbed by radiating far-infrared energy, rated from 0 to 1. It is independent of solar reflectance, and a surface with low emittance cannot shed heat by radiation and runs hotter; ASTM C1371 is one test method for measuring it.

Thermal shock

The sudden contraction of roofing when a hot surface is cooled fast, as when a summer storm drops a dark low-slope membrane from over 180 degrees F by as much as 100 degrees in 15 minutes or less. The repeated rapid change in size stresses the membrane and shortens its service life.

Thermal splitting (shingle cracking)

Horizontal or diagonal cracks through asphalt shingles caused by asphalt shrinkage, deck movement and low mat tensile strength acting together, and made worse by cold-weather installation and improper fastening. It is a product and aging condition, not storm damage, and lighter fiberglass mats resist it less than heavier ones.

Thermoplastic membrane

A roofing membrane made from a polymer that softens when heated and hardens again when it cools, and can repeat that cycle without breaking down. That behavior is what lets TPO and PVC sheets be fused together at their laps with hot air. Contrast with thermoset membranes such as cured EPDM, which do not remelt.

Three-point contact

The ladder-climbing habit OSHA teaches of always having three limbs on the ladder, both hands and one foot or both feet and one hand, while facing the rungs. The same OSHA card tells climbers to keep the body near the middle of the step and never to stand on the top three rungs of a straight or extension ladder.

Three-tab shingle

A single-layer asphalt shingle with two cutouts that form three uniform tabs. Once the residential standard, three-tabs are lighter and less wind- and impact-resistant than laminated shingles, and most major manufacturers have discontinued them.

Tie-in (tie-off)

The watertight transition seal that ends a run of roofing or waterproofing, either where it meets the top or bottom of a flashing or by sealing it to the substrate, an existing membrane or an adjacent roof system. A tie-in can be temporary or permanent, unlike a water cutoff, which is always permanent.

Tile batten

A horizontal wood strip, commonly nominal 1 by 2 inches, fastened across the roof deck so that lugs on the underside of each tile can hook over it. Battens set each course at the correct headlap and give the tile a nailing base; they may be laid on the deck or raised on a counter-batten system.

Tile valley metal (ribbed valley)

Valley flashing made for tile roofs, formed with raised ribs, including a center splash-diverter rib at least 1 inch high, to control the runoff carried in the trough beneath the tile. Tile details extend it at least 11 inches each way from the centerline and lap the tile at least 4 inches onto it, securing cut pieces with adhesive, wire ties, clips or batten extensions.

Tin roof (tin plate)

Strictly, a roof of iron sheet coated with tin, laid in standing seams or as embossed tin shingles and kept well painted, usually red. Once American rolling mills made it cheap, its low cost, light weight and low upkeep made tin plate the most common roofing material of the 19th century; it is often confused with terne plate.

Toeboard

A low barrier along an elevated edge that keeps tools and materials from falling and gives the feet a stop; OSHA requires one to be at least 3 1/2 inches tall with no more than a 1/4-inch gap beneath. On a steep roof with guardrails the rail system must include toeboards, and roofers also use the word for a plank set on roof brackets.

Topographic wind speed-up

The rise in wind speed over the top half of a lone hill, ridge or escarpment that stands out abruptly from the surrounding land. Where a jurisdiction has records of damage from it, IRC Section R301.2.1.5 has the house designed for an increased basic wind speed, and if that adjusted speed reaches 140 mph the house falls under wind design required.

Torch-applied (torch-down) membrane

A way of installing polymer-modified bitumen sheets with open-flame propane torches: the installer heats the bitumen until it melts and presses the sheet into it, bonding it to the surface below and fusing the laps. Because it uses an open flame, fire-safety practices such as a thermal barrier over combustible substrates go with it.

TPO (thermoplastic polyolefin) membrane

A single-ply roofing sheet whose main polymer is a polyolefin blend, built around a reinforcing scrim and joined at the laps by heat welding. ASTM D6878 is the material specification: it requires the scrim and requires that the sheet can be welded or adhesively bonded to itself, while leaving wind uplift, fire and field seam strength to the tested roof system.

Transferable warranty

A manufacturer warranty that can pass to a later owner when the house is sold. Transfers are often limited to one, and coverage may shrink: one shingle warranty keeps most of its terms for a transfer during the early non-prorated period but cuts coverage to 2 years from the date of a later transfer, and it counts a foreclosure as a transfer.

Tubular daylighting device (TDD)

A fixed, non-opening skylight that carries daylight from a glazed cover on the roof down a tube with a reflective lining to a translucent panel at the ceiling. The IRC treats it as fenestration that may be factory built or assembled on site from a kit, and requires it, like a unit skylight, to be tested and labeled to AAMA/WDMA/CSA 101/I.S.2/A440.

Two-party check (mortgagee payment)

An insurance check made payable to both the homeowner and the mortgage lender, because the lender is named on the policy and has a financial interest in the repair. The lender must endorse it and may hold the money in escrow, releasing it in stages as roofing work is completed.

UL 1897

The UL test method for uplift resistance of roof covering systems, which uses static air pressure to measure how well membranes, base sheets and insulation stay attached to the deck. UL notes it is a comparative, short-term static test and does not reproduce real gusting wind.

UL 580 uplift class (30, 60, 90)

Classes assigned under UL 580, a test that subjects a roof deck and its covering to static and oscillating uplift pressures. An assembly must pass the Class 30, Class 60 and Class 90 phases in order, so a Class 90 rating means it survived all three. The classes are comparative ratings, not wind speeds.

Underlayment

The water-resistant layer installed over the roof deck and beneath the primary roof covering. It provides a secondary barrier against wind-driven rain and protects the deck during installation. Materials include asphalt-saturated felt and synthetic underlayments.

Underlayment where wind design is required

Where IRC Figure R301.2.1.1 shows that wind design is required, the 2021 IRC upgrades shingle underlayment to ASTM D226 Type II or ASTM D4869 Type III or IV, laid as two layers (a 19-inch starter strip, then 36-inch sheets lapped 19 inches) and held with cap nails on a grid about 12 inches apart, closing to 6 inches along laps. Self-adhering underlayment labeled to ASTM D1970 is an accepted alternative.

Unvented (conditioned) attic

An attic built without ventilation openings so that it sits inside the building's thermal envelope, insulated at the roof deck instead of the attic floor. IRC Section R806.5 allows it only under listed conditions, including air-impermeable insulation against the underside of the sheathing or enough rigid insulation above the deck to keep the sheathing warm enough to control condensation.

Urban heat island

The extra heat that builds up in cities where roofs, pavement and buildings absorb and re-radiate the sun's energy and there is little vegetation to cool the air. The EPA notes that on a warm day conventional roofing can run as much as 66 degrees F hotter than the surrounding air, and it promotes cool roofs and green roofs as ways to reduce the effect.

Valley

The internal angle formed where two sloping roof planes meet, channeling a large volume of runoff. Valleys are lined with metal or membrane and are a common leak point if improperly flashed — see valley flashing.

Valley lining

The protective layer installed down a valley before shingles go on. Under IRC R905.2.8.2, an open valley may be lined with corrosion-resistant metal at least 24 inches wide or two plies of mineral-surfaced roll roofing, and a closed valley with a 36-inch ply of smooth roll roofing; self-adhering membrane meeting ASTM D1970 is also permitted.

Vapor retarder

A material installed on the warm-in-winter (interior) side of a ceiling or wall that limits how much water vapor passes through the assembly. Under IRC R806.2, a Class I or II vapor retarder in cold climate zones is one way to qualify an attic for the reduced 1/300 ventilation ratio.

Vegetation-free border zone

A strip left clear of plants and growing media around the edges of a green roof and at penetrations, drains and rooftop structures. ANSI/SPRI VF-1 requires this border to be at least 3 feet wide as a fire safeguard, though its commentary notes that the wind design standard, ANSI/SPRI RP-14, will usually set a wider perimeter.

Vegetative (green) roof

A roof that carries living plants over its waterproofing, built up in layers that typically include the membrane, a root barrier, a drainage layer that may hold water, filter fabric, growing media and vegetation. The EPA divides them into lightweight extensive systems and heavier, garden-like intensive systems, and credits them with cooling the roof, slowing stormwater runoff and outlasting a cool roof.

Vented cathedral ceiling (enclosed rafter space)

A sloped ceiling fastened directly to the underside of the rafters, which turns each rafter bay into a closed cavity between the ceiling and the roof deck. IRC R806.1 treats these enclosed rafter spaces like attics that need cross ventilation, and R806.3 requires at least a 1-inch air space between insulation and sheathing at the vents, so each bay needs its own vent path; the alternative is an unvented assembly under R806.5.

Walkway pad

A protective mat or roll, or a line of pavers, installed on a membrane roof along paths people walk to service equipment, such as from a hatch or ladder to rooftop units. Membrane walkway rolls can be welded or adhered to the roof, and manufacturers call for walkways at hatches, ladders and equipment that is serviced regularly.

Warning line system

A rope, wire or chain barrier hung with high-visibility flags no more than 6 feet apart and held 34 to 39 inches high, set at least 6 feet back from the edge of a low-slope roof (4 in 12 or less in OSHA terms). It marks the area where roofing work may proceed, and OSHA allows it only in combination with guardrails, safety nets, personal fall arrest or a safety monitor.

Warranty claim notice

The owner's duty to tell a manufacturer promptly about a suspected product defect before it will honor the warranty. Terms typically ask for proof of ownership and purchase date and let the maker inspect or take shingle samples; one major shingle warranty requires notice within 30 days of discovering the defect.

Waste factor

The extra shingle material added to a measured roof area to cover trimming at valleys, dormers, hips, rake edges and penetrations. The asphalt shingle industry's residential manual puts trim waste at about 2 to 10 percent, with more complex roofs at the high end.

Water cutoff

A permanent detail built into a roof assembly to stop water from traveling sideways through the insulation, so that a leak or wet area is confined to one isolated section of the roof. It differs from a tie-in, which may be only a temporary seal.

Wear and tear exclusion

The standard home insurance exclusion for deterioration from age, weathering and ordinary use. An insurer will not buy a new roof simply because the old one is worn out; a roof claim has to rest on damage from a covered event such as a storm or a falling tree.

Weather blocking (tile)

Moldable or preformed rigid material, such as mortar or a preformed closure, fitted into the gaps between field tile and trim tile or between tile and flashing to stop wind-driven rain from getting in. Tile installation guidance calls for it at hips, ridges and headwalls, including chimneys and skylights, so water stays on top of the field tile.

Weather checks (nose lugs)

Ribs or ridges molded into a roof tile, including lugs on the underside near its nose, that hold back wind-driven rain trying to travel between one course of tile and the next. They are separate from the anchor lugs that hang the tile on its batten, and they are left out when tile thickness is measured.

Wet storage stain

A bulky white or gray corrosion product that forms on new galvanized sheet and other zinc-coated steel when it is stacked or bundled tightly while damp, so trapped moisture and poor airflow let the zinc corrode quickly. Light staining usually does not shorten coating life, but heavy buildup can badly damage it, so bundles should be kept dry, raised and ventilated.

Wildland-Urban Interface (WUI)

The zone where homes and other structures meet or intermingle with wildland vegetation, creating elevated wildfire risk. In Colorado the WUI covers roughly 4.5 million acres and is home to about half the state's population.

Wind crease

A fold line across an asphalt shingle or tab, near where it is nailed under the course above, left when wind breaks the sealant bond and flips it upward. Creasing, tearing or missing pieces are the marks of genuine wind damage; unsealed shingles with no crease or tear point to a cause other than high wind.

Wind design required (IRC)

The point at which the IRC stops letting builders use its prescriptive wind rules: areas shown on Figure R301.2.1.1, and special wind regions where the ultimate design wind speed is 140 mph or more. There the house has to be designed for wind using a method such as the AWC Wood Frame Construction Manual, ICC 600, ASCE 7 or the IBC, and roof details such as underlayment become stricter.

Wind exposure category

A rating of the terrain around a building that adjusts wind loads: Exposure B is urban, suburban or wooded land with many closely spaced obstructions; C is open terrain with scattered obstructions; D is flat, unobstructed ground facing open water, mud flats, salt flats or unbroken ice. Where a site sits between two, the harsher category governs.

Wind gust (peak gust)

A brief surge in wind speed above the prevailing flow; the National Weather Service reports gusts when speed swings 10 knots or more between peaks and lulls, and the peak gust is the highest instantaneous speed recorded. Tornado ratings on the EF scale are estimated 3-second gusts, while routine weather station readings use a longer averaging period, so the two kinds of figure are not interchangeable.

Wind mitigation inspection

An inspection recorded on Florida's uniform mitigation verification form that documents a home's wind-resisting features, including roof covering approval, roof deck attachment, roof-to-wall connections, roof shape, secondary water resistance and opening protection, for use in premium discounts. The form stays valid for up to five years if the structure is not materially changed.

Wind rating (ASTM D3161 / D7158)

Standardized wind-resistance classifications for asphalt shingles: ASTM D7158 Classes D, G, and H (Class H is tested for basic wind speeds up to 150 mph) and ASTM D3161 Classes A, D, and F. Class H or F products, correctly nailed with proper starter courses, are the norm along Colorado's wind-prone Front Range.

Wind uplift

The suction wind creates on a roof as air flows over it, pulling the covering, insulation and deck away from the structure. Required resistance is calculated from the design wind speed, exposure and building shape, and roof systems are rated for it by pressure tests such as UL 580, UL 1897 and FM 4474.

Wind warranty (blow-off coverage)

The part of a shingle warranty that covers shingles blowing off in winds, including gusts, up to a stated speed. Higher ratings usually carry conditions: one maker's upgrade to 130 miles per hour for the first 15 years requires its matching starter and hip and ridge products and excludes installation over existing shingles.

Wind/hail deductible

A separate deductible that applies only to damage from windstorm or hail, often set as a percentage of the dwelling limit, typically 1 to 5 percent, while other losses keep the standard dollar deductible. Whether a policy carries one, and at what level, depends on the insurer and the state.

Windborne debris region

Parts of hurricane-prone regions where wind-driven debris is expected, so glazed openings need impact protection. The IRC places them within 1 mile of the mean high-water line where Exposure D applies and the ultimate design wind speed is 130 mph or more, anywhere the speed is 140 mph or more, and in Hawaii.

Wire-tie tile system

A code-approved way of fastening clay or concrete tile with wire instead of nailing each tile, typically twisted wire runs anchored at the top and bottom of the roof with the tiles tied to them. It keeps penetrations through the underlayment to a minimum and lets tile go on decks that will not hold nails; the attaching wire must be at least 0.083 inch in diameter.

Wood fiberboard

A lightweight board made mainly of cellulose fibers from wood, paper or paperboard, with or without binders. In low-slope roofing it serves as insulation and as a cover board laid over foam insulation, where it keeps hot bitumen from blistering the foam and protects the foam beneath single-ply membranes.

Wood nailer (blocking)

Dimensional lumber or plywood fastened to a structural deck or wall to give the fasteners for membrane, flashing or edge metal something solid to grip. Nailing strips set into or onto decks and walls that will not hold nails serve the same purpose. Nailers are also called blocking.

Wood shake

A wood roofing unit with at least one split face, traditionally split from cedar, which gives it a rough, irregular surface and thicker butt than a shingle; tapersawn shakes are the sawn exception. Shake roofs are laid with strips of felt interlayment between courses.

Wood shingle

A wood roofing unit sawn smooth on both faces and tapered from a thick butt to a thin tip, thinner and more uniform than a shake. Cedar shingles are made in 16, 18 and 24-inch lengths, and unlike shakes they are laid without felt interlayment between courses.

Workmanship Warranty

A warranty provided by the roofing contractor covering installation errors, such as improper nailing or faulty flashing, rather than product defects. It is separate from the manufacturer's material warranty and is only as reliable as the contractor's continued existence, unless it is a manufacturer-backed system warranty.

Woven valley

A closed valley in which shingles from both roof planes are run across the valley centerline and interlaced course by course, so no valley lining shows. Because every shingle is bent into the valley, manufacturers caution against it in cold weather and for some thick laminated products, and nails are kept at least 6 inches from the centerline.

WPI-8 (Texas windstorm certificate of compliance)

The certificate the Texas Department of Insurance issues to show that construction on the Texas coast meets the windstorm building code; most properties need one to buy a Texas Windstorm Insurance Association policy. A WPI-8 covers work inspected while underway by a TDI inspector or appointed engineer and a WPI-8-E covers finished work inspected by a licensed engineer. Most roof replacements need one; repairs under 100 square feet that leave the decking alone do not.

Xactimate

Estimating software from Verisk that insurers, adjusters and restoration contractors widely use to write property claim estimates line by line. Its prices come from Verisk price lists researched for local market areas and updated regularly, so the same repair can price differently from one region to another.

Zinc patina

The protective surface layer, a zinc hydroxycarbonate, that forms on architectural zinc as it reacts with oxygen, moisture and carbon dioxide in the air. It lets light scratches heal over time, but it needs air on both faces of the sheet; zinc laid without underside ventilation, over a wet or unvented substrate, can corrode from the underside instead.