As wildfires continue to impact communities across the greater Los Angeles area, more and more neighborhoods are being reclassified as High Fire Hazard Severity Zones (HFHSZ). Whether you’re building a new home or remodeling an existing one, choosing the right exterior materials is now more important than ever, not just for aesthetics and performance, but for safety and compliance.

So, what exactly does combustibility mean, and how does it affect your home?

What is Combustibility?

(In Plain English)

Combustibility refers to whether a material will ignite, burn, or contribute to the spread of fire. In architecture, we evaluate how each component of a building—from the roof down to the siding and even the deck—might react under intense heat and flame exposure.

Materials are generally classified into three categories:

Common Residential Materials:

Combustibility at a Glance

How Architects Design for Fire Resistance

While selecting non-combustible materials is ideal, design often requires balancing safety with other goals like texture, warmth, and cost. Here’s where smart detailing comes into play:

Architects can modify assemblies to include:

• Fire-rated sheathing (like DensGlass or Type X gypsum) under wood siding.
• Class A-rated roofing underlayments beneath asphalt shingles or tiles.
• Metal flashing and ember-resistant vents to block ember intrusion.

The result? You can still use your favorite materials—even if they’re combustible—as long as the overall wall or roof assembly meets code requirements for fire resistance.

Our Role as Your Architects

We evaluate every component for its ignition potential and assembly rating, ensuring your home not only looks beautiful but also stands up to the realities of our changing climate. As zones are reclassified and codes evolve, we guide you through choices that keep your family safe while maximizing design flexibility.