CBC Chapter 7A: Soffits & Vents for Wildfire Compliance

What is CBC Chapter 7A?

California Building Code (CBC) Chapter 7A establishes construction standards for buildings located in Wildland-Urban Interface (WUI) fire hazard severity zones. These requirements are designed to improve a structure's ability to resist ignition from wildfire exposures including flame impingement, radiant heat, and ember intrusion.

The code specifically addresses exterior components that are most vulnerable to wildfire, including roofing, siding, windows, decks, and critically, soffits and vents. These openings can allow wind-blown embers to enter attic spaces and ignite combustible materials, making proper protection essential for wildfire resistance.

Soffit Requirements

According to CBC Section 704A.3.2.1, eaves and soffits must be constructed with one of the following materials to meet wildfire protection standards:

Noncombustible Materials

Noncombustible soffit materials provide the highest level of fire resistance. Approved materials include:

• Aluminum soffits - Lightweight, corrosion-resistant, and maintenance-free
• Steel soffits - Heavy-duty option for commercial applications
• Copper soffits - Premium option with natural antimicrobial properties
• Fiber cement panels - Durable composite material with wood-like appearance

Find compliant soffit and vent products in our roof edges, vents & trim category, including noncombustible materials and ember-resistant vent systems.

Ignition-Resistant Materials

Ignition-resistant materials must pass specific fire testing standards to qualify for use in WUI zones. These materials include:

• Fire-retardant treated wood (FRTW) that meets ASTM E84 Class A flame spread requirements
• Exterior fire-retardant treated plywood with a State Fire Marshal (SFM) listing
• Products with current ICC-ES evaluation reports demonstrating compliance

Vent Requirements

CBC Sections 706A.2.1–2.2 establish strict requirements for vents in WUI zones to prevent ember intrusion while maintaining necessary attic ventilation. All vents must be designed to resist the intrusion of flame and embers.

Mesh Sizing Standards

Vent openings must be covered with corrosion-resistant noncombustible wire mesh with openings that meet the following criteria:

• Minimum opening: 1/16 inch (prevents moisture buildup and ensures proper ventilation)
• Maximum opening: 1/8 inch (blocks ember intrusion)
• Material requirements: Corrosion-resistant metal (stainless steel, aluminum, or galvanized steel)

Types of Compliant Vents

Several vent types can meet CBC 7A requirements when properly designed and installed:

• Ember-resistant vents: Specifically designed with intumescent coatings that expand when exposed to heat, sealing the opening
• Brandguard vents: Feature a unique baffle design that blocks embers while maintaining airflow
• Vulcan vents: Use multiple layers of fine mesh to trap embers while allowing ventilation
• Standard vents with approved screening: Traditional vents retrofitted with 1/16" to 1/8" corrosion-resistant mesh

Inspection Checklist

Building inspectors will verify the following items for CBC 7A compliance:

Approved Products & Documentation

To ensure compliance and pass inspection, use products that have been tested and approved for use in WUI zones. All products must have proper documentation including CAL FIRE listings, ICC-ES reports, and manufacturer specifications.

View our full selection of roof edges, vents & trim or contact our technical support team for assistance with product selection and specification.

Additional Resources

For more information on CBC Chapter 7A compliance and wildfire-resistant construction:

• CAL FIRE Building Materials Listing Program
• ICC Evaluation Service
• Building Codes & Standards Resource Center
• Roof Edges, Vents & Trim Products