What ember-resistant design is recommended for attic and crawlspace vents?

• A. Vents are not important
• B. Use standard vents with large mesh
• C. Vents are common ember entry points; use ember-resistant vents with 1/8 inch (3 mm) or smaller mesh and sealable or airtight designs.
• D. Seal vents to keep air out

Answer: (C)

Embers can sneak into attic and crawlspace spaces through vents during a wildfire, so the vent design must block embers while still allowing ventilation. The recommended approach is ember-resistant vents that use a very small mesh—1/8 inch (3 mm) or smaller—and are sealable or airtight. The tiny mesh catches embers trying to pass through, and the sealable or airtight feature lets you close or tightly seal the vent when embers are present or when the space doesn’t need ventilation, dramatically reducing the chance of ignition from inside the vent opening. Proper installation matters too, with a tight seal around the edges to prevent ember intrusion around the vent. This choice balances the need for ventilation with practical ember protection, unlike standard vents with larger mesh that admit embers, or vents that are sealed shut and stop ventilation altogether.