What vent design is typically recommended to reduce ember intrusion?

• A. 1/8 inch mesh ember-resistant vents
• B. Seal gaps around vent openings
• C. Large plastic vent covers
• D. No vents

Answer: (A)

Ember intrusion through vents is a major ignition path in wildland-urban interface structures, so the vent design should block embers while still allowing ventilation. Using ember-resistant vents with a tight mesh is the best approach because the 1/8 inch mesh size effectively stops burning embers from entering the attic or wall cavities, yet lets air flow continue to relieve pressure and reduce fire stress on the building envelope.

Sealing gaps around vent openings can help reduce air leakage, but it doesn’t address embers entering through the vent openings themselves when venting is needed. Large plastic vent covers are not reliable in a fire; they can warp, melt, or fail, potentially increasing vulnerability. No vents would eliminate ember entry through vents but would prevent necessary ventilation, leading to increased heat and moisture problems and other fire risks.