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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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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-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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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 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.

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 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.

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.

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.

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.

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.

Soffit

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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 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.

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.