What are 1/8 inch mesh vents and why are they recommended in WUI construction?

• A. They are decorative vent screens.
• B. They are ember-resistant vent screens that block ember entry; 1/8 inch (3 mm) mesh prevents embers from entering structures.
• C. They are for water drainage and moisture control.
• D. They are designed to be decorative and not affect ember penetration.

Answer: (B)

Ember-resistant venting is used to keep embers from entering a building through vents during a wildfire while still allowing the structure to breathe. The 1/8 inch mesh size provides a barrier that blocks most embers that could land inside attics or crawlspaces and ignite hidden fuels. At the same time, this mesh size is small enough to maintain adequate airflow for moisture control, helping to prevent mold and wood decay inside vented spaces. These vents are specifically for ember protection, not for decoration or drainage, and they’re installed with proper sealing and flashing to maximize protection. In wildfire-prone areas, this approach reduces the primary ignition risk from embers entering the building through vents, making it a recommended practice in WUI construction.