AB 3074 and Ember-Resistant Vents: What California Homeowners Need to Know

California Assembly Bill 3074, signed into law in 2020, introduced a new zone of defensible space and strengthened requirements for ember-resistant vents on new construction in High and Very High Fire Hazard Severity Zones (HFHSZ).

What AB 3074 Requires

The bill created Zone Zero - a 0 to 5-foot ember-resistant area immediately adjacent to any structure, where combustible materials are to be removed or replaced with noncombustible alternatives. Important: AB 3074 put Zone 0 into statute, but it takes effect through regulations adopted by the Board of Forestry and Fire Protection. Confirm the current effective and phase-in dates before treating it as enforceable on your property - our [Requirements Finder](/requirements) shows where it currently stands for your address.

Vent requirements themselves live in Chapter 7A of the California Building Code, which applies to new construction and to vents that are installed or replaced. Rather than a blanket "AB 3074 compliant" label, the right question on any project is whether the specific vent product carries the applicable listing and approval for wildland-urban interface exposure.

Does It Apply to Existing Homes?

Chapter 7A vent requirements apply to new construction and to vents you install or replace. They do not retroactively require existing homeowners to replace vents that are already in place.

However - and this is critical - existing homes are not exempt from the risk. Standard foundation and attic vents on older homes are one of the primary ember entry points in wildfire events. Just because you're not legally required to upgrade doesn't mean you're protected.

Insurance carriers conducting aerial property assessments don't distinguish between code-required and voluntary upgrades - they assess observable risk.

What Ember-Resistant Vents Actually Do

Wildfire Defense Systems tests show that standard 1/4" mesh vents allow significant ember penetration. The 1/16" mesh or enclosed vent designs dramatically reduce ember entry - and in many wildfire scenarios, blocking ember entry is the single most important factor in whether a structure survives.

A typical home has 6–15 vents in the roof, soffits, foundation, and walls. Replacing them with listed ember-resistant designs is usually a few hundred to low thousands of dollars - one of the best dollar-for-dollar risk reduction investments available.

Getting Your Vents Assessed

During any in-person assessment, Anthony will identify every vent on your property, assess its ember resistance, and provide a prioritized recommendation. Vent replacement is almost always in the top-priority tier because of its high impact and relatively low cost.

If you're not sure whether your vents are compliant, don't guess - schedule an assessment.