Post-fire research from IBHS, NIST and state fire agencies consistently finds that most homes lost in wildfires are ignited by wind-blown embers rather than direct flame contact. That is why the code treats vents, gutters and valley flashing as core requirements alongside the Class A covering, and why these details deserve as much attention as the shingle you pick.
Ventilation openings, the dominant ember pathway
Section 403.4 covers vents for enclosed attics, enclosed rafter spaces and underfloor spaces. There are two compliant paths, and they apply to ridge vents, off-ridge vents, gable vents, soffit and eave vents and other roof penetrations.
- Performance path: fully covered with vents listed to ASTM E2886, with no flaming ignition of cotton in the ember intrusion test, no flaming ignition in the flame intrusion integrity test, and the unexposed side not exceeding 662 degrees Fahrenheit.
- Prescriptive path: covered with noncombustible corrosion-resistant mesh with openings not exceeding 1/8 inch.
- General wildfire guidance often cites 1/16 to 1/8 inch mesh. The code's prescriptive minimum is 1/8 inch, and listed ASTM E2886 vents are the higher standard.
Valley flashing
Section 403.2.2 requires valley flashings of at least 0.019 inch, which is No. 26 galvanized sheet gage, corrosion-resistant metal, installed over a minimum 36-inch-wide underlayment of one layer of ASTM D3909 cap sheet running the full length of the valley. Valleys collect embers and debris, which is exactly why the code details them specifically.
Gutters and downspouts
Section 403.3 requires gutters and downspouts to be noncombustible, which rules out vinyl and other plastic gutters in mapped areas. The code itself does not mandate gutter guards, but dry debris in gutters is a documented ignition point, so noncombustible gutter covers are strong practice. Where downspouts discharge also matters, because it interacts with the 0 to 5 foot noncombustible zone.
Class 2 additions at the roof edge
In Moderate and High intensity areas the code adds requirements that touch where the roof meets the wall.
- Eaves and soffits: protected on the exposed underside with noncombustible or ignition-resistant materials, 1-hour rated construction, 5/8-inch Type X drywall, or specified lumber or fire-retardant-treated wood.
- Fascia: required, and protected on the backside by noncombustible or ignition-resistant materials or 1-hour construction.
- Wall-to-roof flashing: a minimum 6 inches of metal flashing or noncombustible material installed vertically between wall sheathing and cladding at ground, decking and roof intersections.
- Skylights: tempered glass, multilayered glazed panels, glass block, or a 20-minute fire protection rating. Plastic-domed skylights can melt and admit embers.
Solar and chimneys, stated honestly
The 2025 code as written does not spell out solar attachment or chimney spark-arrestor provisions in its roofing sections. Those are typically handled under the fire code or local amendments. Spark arrestors and careful solar penetration detailing are strong practice, and we confirm the local requirement rather than claiming a state mandate that is not there.
The debris and defensible-space link
The code carries its own defensible-space requirements by ignition zone, and roofing sits right in the middle of them. The 0 to 5 foot immediate zone calls for noncombustible surfaces such as rock, gravel, concrete or pavers, removal of shrubs, combustible mulch and woody debris, and tree crowns within 10 feet of the structure pruned back to a 10-foot clearance. Roof debris, gutter debris and overhanging branches are the connection between your roof and those zones. If your budget is limited, the highest-value order is ember-resistant vents, then roof gaps and repairs, then the 0 to 5 foot zone, then windows.
Requirements vary by jurisdiction
Colorado's wildfire code is a state minimum, but adoption and enforcement happen locally, and adoption is uneven. Some counties, towns and fire districts adopted the code, some adopted amended or more stringent versions, and some declined. Nothing on this page tells you what applies to your specific address. We confirm the current adopted code and map with your building department before every project in a wildfire area, and we put the answer in writing with the estimate.
Common questions
- Do I need ember-resistant vents when I reroof?
- In a mapped WUI area, yes. Vents on enclosed attics, rafter spaces and underfloor spaces must either be listed to ASTM E2886 or be covered with noncombustible corrosion-resistant mesh with openings no larger than 1/8 inch.
- Are vinyl gutters allowed in a Colorado wildfire area?
- No. The code requires gutters and downspouts to be noncombustible, which excludes vinyl and other plastic gutters in mapped areas.
- Does a Class A roof alone make my home fire-safe?
- No. The covering is necessary but not sufficient. Embers entering vents, debris igniting in gutters and combustible material within the first 5 feet are the dominant ignition pathways, which is why the correct term is home hardening rather than fireproofing.
Talk to us about your roof
We work out of 9822 Titan Park Cir, Littleton, and cover the Front Range foothills where this code matters most. Call (303) 738-1032 or book an inspection and we will confirm the local requirements, walk the roof, and put the 25% answer in writing with your estimate. Our neighborhood guides and service areas show where we work, and the insurance claim guide covers the documentation side.