Glossary / ember-resistant
Ember-resistant vents
Meant to stop wind-blown embers. Listed vents, 1/16–1/8 inch mesh, and Zone 0 are different ember-resistant tools. The phrase is not a listing ID.
Ember-resistant describes a tool meant to stop wind-blown embers, the burning fragments that ignite most homes lost in wildfires. Three different tools carry the phrase, and the phrase is not a listing ID.
Listed vents. A vent assembly tested to ASTM E2886 for ember intrusion and flame intrusion, listed in California's OSFM handbook category 8165 by model. Colorado's 2025 CWRC 403.4.1 names listed E2886 vents as one Class 1 path; Oregon R327, where adopted, allows vents designed to resist burning embers and flame, and restricts eave and soffit vents to such manufactured vents or openings 12 feet or more above grade.
Mesh. Noncombustible, corrosion-resistant metal mesh with openings of 1/16 to 1/8 inch is the prescriptive path: CAL FIRE guidance (row), IBHS Wildfire Prepared (row), Colorado CWRC at 1/8 inch (row). Quarter-inch mesh keeps animals out and lets embers through. Mesh is not a listed vent and the two do not always substitute for each other (mesh versus listed vents).
Zone 0. The first five feet kept noncombustible is the ember-resistant zone in IBHS Wildfire Prepared and in California guidance (Zone 0).
Retrofit. IBHS Essential, the ember designation, is built from exactly these: a Class A roof covering path, vents or 1/8 inch mesh, a 0–5 foot noncombustible zone, noncombustible gutters. A perforated fiber-cement soffit is cladding, not an ember-resistant vent. The vents hub holds the listed models and the places where the rule differs.
Questions
What is an ember-resistant vent?
A vent assembly that resists ember entry and direct flame, shown by an ASTM E2886 test and, in California, an OSFM 8165 listing by model. Fine metal mesh is the prescriptive alternative, not the same product.
What are ember-resistant roof vents?
Ridge, off-ridge and gable vents tested as assemblies to ASTM E2886 and listed under OSFM 8165. Not every ridge-vent geometry passes, and the listing is by model.
What kind of vent mesh is recommended to prevent ember intrusion?
Noncombustible, corrosion-resistant metal mesh with openings from 1/16 to 1/8 inch, per CAL FIRE guidance and the IBHS standard; Colorado's CWRC sets 1/8 inch. Quarter-inch mesh keeps animals out and lets embers through.
Are ember-resistant vents required?
It depends on the adopted book. Oregon R327 requires a manufactured ember- and flame-resistant vent, or a 12-foot-high opening, at eaves and soffits; Colorado CWRC names listed E2886 vents as one path beside 1/8 inch mesh; IBHS accepts vents or mesh; California specifiers commonly use an OSFM 8165 model.
Do not use as a synonym: fireproof.
Related
Where this term is used
- Artificial turf in Zone 0
- Bird blocks, boxed soffit, or unvented attic
- Building code upgrade coverage
- California AB 38 seller disclosure
- Deck ledger and the wall intersection
- Dryer vents versus mesh
- Garage doors as an ember path
- Gravel and pavers under the deck