What mesh size is recommended for ember-resistant vents?

• A. 1/8 inch (3 mm) or smaller mesh
• B. 1/2 inch mesh
• C. 2 inches mesh
• D. 1/16 inch mesh

Answer: (A)

Ember exposure through vents is a common wildfire ignition path, so vents must use a mesh small enough to stop embers from entering the attic or crawl space. The recommended size is 1/8 inch (3 mm) or smaller because it blocks most embers that could start a fire while still allowing adequate ventilation. Larger meshes would let embers through and defeat the purpose of an ember-resistant vent. A finer mesh like 1/16 inch would also block embers, but the standard guidance emphasizes 1/8 inch or smaller as the practical, widely accepted requirement.