Ember-resistant vent
An attic, eave, or foundation vent screened or baffled so wind-blown embers can't get inside and ignite the home.
Vents are one of the most common ways a home ignites in a wildfire: embers ride the wind through attic and crawl-space vents and land on stored boxes, insulation, or framing. An ember-resistant vent blocks that path — at minimum by covering openings with 1/8-inch noncombustible metal mesh (never plastic or fiberglass screen, which melts), and ideally with a listed, baffled vent tested to resist both embers and flame. It's a cheap, high-impact piece of [home hardening](/guides/wildfire-home-preparation) that protects the [attic](/maintenance/roof-gutters) you can't easily watch during a fire.