Ember-resistant vents: how to keep embers out of your attic

Why vents matter

Your attic, crawl space and eaves need airflow, so they have openings to the outside. During a wildfire, wind drives embers into those openings. Once inside an attic full of dry framing and dust, an ember can start a fire you can't see until it's through the roof.

The problem with standard screens

Many older homes have 1/4 inch screens on their vents. Those openings are large enough for embers to pass through. Plastic and fiberglass screens are worse, because they melt and leave the opening wide open.

Which mesh to use

Fire safety groups recommend corrosion-resistant metal wire mesh with openings of 1/8 inch or 1/16 inch. California's wildfire building code for new construction in high hazard areas, now the California Wildland-Urban Interface Code (Title 24, Part 7, in effect since January 1, 2026, replacing the old Chapter 7A), uses that same 1/16 to 1/8 inch range.

Finer mesh blocks more embers, but it also cuts airflow and clogs quickly with dust, lint and cobwebs. Poor attic airflow can lead to moisture, mold and rot. For most retrofits, 1/8 inch metal mesh is the practical choice. If you use 1/16 inch mesh, plan to inspect and brush it clean at least twice a year, and ask a contractor to confirm your attic still gets enough ventilation. Tested ember-resistant vents with baffles are another way to block embers without choking airflow.

Vent by vent

Foundation and crawl space vents

Low on the wall and easy to reach, these are a simple weekend retrofit. Screw 1/8 inch metal mesh over the inside or outside of the opening, or replace the vent cover.

Eave and soffit vents

These sit where heat and embers collect under the roof overhang. Mesh alone is often not enough here. Fire safety groups recommend vents with internal baffles that block embers, backed by fine metal mesh.

Gable vents

Gable vents on the end walls of the attic face straight into the wind. Research groups suggest avoiding them where possible. If you keep them, use a wildfire-resistant model that has passed the ASTM E2886 ember test.

Dryer and bathroom exhaust vents

Use metal covers with flaps that close when the fan is off. Never use mesh on a dryer vent, since lint will clog it and create a fire hazard of its own.

Upgrading to ember-resistant vents

Tested ember- and flame-resistant vents are designed to stop embers while keeping more airflow than fine mesh alone. In California, look for products accepted by the Office of the State Fire Marshal. They cost more than mesh but are worth it on eaves and gables, the vents most exposed to wind and heat.

Quick vent checklist

1. Find every vent: foundation, eave, gable, attic, dryer and bath fans.
2. Check the screen size and material on each one.
3. Replace anything plastic, torn or 1/4 inch with 1/8 inch metal mesh.
4. Plan ember-resistant vents for eaves and gables.
5. Clean mesh before fire season so it doesn't clog.

This guide is general information, not professional advice. Building codes and defensible space rules vary by state, county and fire district. Your local fire department or a qualified contractor can tell you what applies to your home. No home is fireproof. Read our full disclaimer.