Home / Roofing Permits / Colorado Jurisdictions Requiring Class 4 Impact-Resistant Shingles
Colorado Jurisdictions Requiring Class 4 Impact-Resistant Shingles
Jurisdictions whose own adopted-code amendments or published roofing regulations MANDATE UL 2218 Class 4 impact-resistant asphalt shingles — a requirement, not an insurer discount. The confirmed mandates cluster in the northern Front Range (Fort Collins, Loveland, Berthoud, Johnstown, Timnath, Larimer County, Boulder County) plus Lafayette; each card quotes the jurisdiction’s own amendment and its exceptions. Most Colorado jurisdictions have NO such mandate — absence from this list means none was found in the jurisdiction’s own sources, not that Class 4 is a bad idea in hail country.
Boulder County - Community Planning & Permitting (Boulder County, Colorado (unincorporated))
"Asphalt shingles shall be Class 4 impact resistant, tested in accordance with UL 2218, see Boulder County Building Code (BCBC) amendment IBC section 1504.8.1 or IRC amendment section R905.2.4.2, as applicable." Exception: if the roof repair/replacement/recover or new roof area of an addition is no greater than 200 sq ft and no greater than 25% of total roof area, the owner may request a code modification from the Building Official (requires a written statement from a roofing contractor/supplier that no matching Class 4 shingles are available).
City of Fort Collins - Building Services (City of Fort Collins, Colorado)
2024 IRC local amendment adds Section R905.2.4.2: "Asphalt shingles shall be Class 4 impact resistant, tested in accordance with UL 2218, and installed in accordance with the manufacturer's installation instructions." Applies to re-roofs via R908.1. Exceptions allow non-Class-4 replacement only when matching color/style Class 4 shingles are unavailable, or for repairs not exceeding 49% of roof area (or additions not exceeding 50% of original building size).
City of Lafayette - Building Division (City of Lafayette, Colorado)
2021 IRC/IBC local amendment: Class 4 Impact Resistant Shingles are required; documentation or packaging of Class 4 IR shingles must be posted on site and shown for inspection along with the Inspection Record Card (effective March 15, 2021).
City of Loveland - Building Division (City of Loveland, Colorado)
"Class 4 shingles required effective June 1, 2022" per the City's Roofing Affidavit form (UL 2218 Class 4 impact resistance); also listed as a shingle requirement for roof replacements covering 50% or more of the roof area in the City's roofing requirements table. Repairs up to 49% of roof area may match the existing (non-Class-4) shingles per the same table.
Larimer County - Building Division (Larimer County, Colorado (unincorporated))
"Class '4' impact resistant asphalt shingles are required for all new construction, repairs over 25%, and roof replacements." Added as IRC R905.2.4.2 by Larimer County's 2024 Building Code Amendments (exceptions exist for color/style-match unavailability and for repairs/additions not exceeding 100 sq ft).
Town of Berthoud - Planning and Building Department (Town of Berthoud, Colorado)
"*Impact Resistance Asphalt Shingles required per R905.2.4 (Amended): Asphalt shingles shall be Class 4 impact resistant, tested in accordance with UL2218, and installed in accordance with the manufacturer's installation instructions."
Town of Johnstown - Building Department (Town of Johnstown, Colorado)
"Impact Resistance Asphalt Shingles required per R905.2.4 (Amended): Asphalt shingles shall be Class 4 impact resistant, tested in accordance with UL2218, and installed in accordance with the manufacturer's installation instructions." This is a genuine local amendment mandate, not a mere recommendation, effective with the town's adoption of the 2024 IRC on January 1, 2026.
Town of Timnath - Building Services (Town of Timnath, Colorado)
Ordinance No. 19, Series 2025 (adopting the 2024 I-Codes) amends IRC section R905.2.4.2, Impact Resistance of Asphalt Shingles: "Asphalt shingles shall be Class 4 impact resistant and tested in accordance with UL 2218." Exception: where no Class 4 product matches the color or style of existing shingles, the Building Official may approve the highest impact class available.
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