Ember-resistant vents are attic, soffit, gable and crawlspace vents that are built or screened to stop wind-blown embers from getting inside the house. Colorado’s 2025 Wildfire Resiliency Code gives two ways to comply on mapped parcels: cover the opening with a listed vent tested to ASTM E2886 that meets three performance limits, or cover it with noncombustible, corrosion-resistant mesh with openings no larger than 1/8 inch. The rule applies to every class of wildland-urban interface parcel, low through high. This page is general information; your building department decides what passes on your home.
On this page: Why vents matter · The two compliance paths · Vent by vent · Retrofit steps
Why vents are an ember path
IBHS reports that embers can travel more than a mile ahead of a wildfire and collect in vulnerable spots, and it names vents first in its list. An attic vent is designed to move air in and out of the roof space, which also means it can pull embers in when the wind is pushing them against the house. Inside the attic, they can land on insulation, framing or stored items.
NIST’s 2022 guidance on hardening says embers are so pervasive that partial fixes give little benefit; one unscreened vent can undo a lot of other work. That is why the state code treats vents as a Class 1 item that every mapped parcel needs, not an upgrade reserved for high-hazard areas.
The two ways a vent can comply
Section 403.4 of the state code covers ventilation openings for enclosed attics, enclosed rafter spaces and underfloor spaces.
| Path | What it requires | Good fit for |
|---|---|---|
| Performance (403.4.1) | A listed vent tested to ASTM E2886: no flaming ignition of cotton in the ember test, no flaming in the integrity test, and the unexposed side no hotter than 662°F (350°C) | New construction, soffit and gable replacements, Class 2 parcels where eaves are being rebuilt anyway |
| Prescriptive (403.4.2) | Noncombustible, corrosion-resistant mesh with openings of 1/8 inch or less | Retrofits of existing vents, foundation and crawlspace vents |
ASTM E2886 itself is a test method, not a rating. Its scope says it covers wall-mounted and under-eave vents, evaluates ember entry and flame penetration in separate procedures, and leaves acceptance criteria to others. The Colorado code supplies those criteria. The scope also excludes ridge and off-ridge field vents.
Vent by vent on a typical Colorado house
- Soffit and eave vents. NFPA’s Firewise list for the immediate zone recommends 1/8-inch metal mesh on eave vents. On Class 2 parcels the eaves themselves must also be protected, so a soffit replacement is the natural time for listed vents. Our WUI siding and eaves guide covers those rules.
- Gable vents. Same rule. A louvered gable vent with 1/4-inch screen behind it does not meet the 1/8-inch path.
- Roof vents and ridge vents. These are part of the roof job. Since E2886 excludes ridge and field vents, ask how the product chosen meets your local code. Our roof ventilation guide explains how intake and exhaust work together.
- Foundation and crawlspace vents. The Colorado State Forest Service recommends 1/8-inch metal mesh on foundation vents too, and on the open space under stilt foundations and decks.
A vent retrofit in five steps
- Count the openings. Walk the house and list every soffit, gable, roof, ridge and foundation vent.
- Check the screen. If it is 1/4-inch, plastic or torn, it needs work.
- Choose a path for each. Mesh over existing vents is usually the cheaper route; listed vents make sense when the soffit or roof is being replaced.
- Keep airflow. Fine mesh can clog with needles and dust. The attic still needs its required ventilation, so plan for cleaning and enough vent area.
- Save the paperwork. For listed vents, keep the product listing with your permit records.
Vents are one piece of the roof system. Pair them with a Class A roof and metal valleys and clean, noncombustible gutters. For the full checklist, see our wildfire home hardening guide, and for when a reroof triggers these rules, our Colorado Wildfire Resiliency Code guide.
Vents on your next roof
Integrity Roofing and Painting is veteran-owned and family-run since 1990, an Owens Corning Platinum Preferred contractor with 650+ Google reviews. On a reroof we inspect the existing roof vents, intake vents and screens and list in writing what the local code asks for on your parcel. We also install ember-resistant vents. In the Colorado Springs area, from Monument to Woodland Park, call (719) 488-2800 for a free inspection. In the Denver metro and foothills, call (303) 209-0152 or book a free Denver inspection.
Sources: 2025 Colorado Wildfire Resiliency Code, section 403.4 (DFPC); ASTM E2886/E2886M, scope; NFPA, Preparing homes for wildfire; Colorado State Forest Service, Protect your home and property; IBHS, Wildfire Prepared Home: About; NIST, holistic home and community wildfire guidance (2022).
