What’s the Difference Between Noncombustible Vs. Fire Resistant? Fine Homebuilding

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Written By Jim J Neal

This article was originally published in Building to Survive In Wildfire Country

These terms are common when you research, design, or choose materials for a home located in a wildfire-prone region. Although “combustible” may sound obvious, the meanings of “noncombustible,” ignition resistant, and fire resistant materials can be quite different. They often serve the same purpose. These definitions will help you find a fire-safe house.


Combustible materials are those that can ignite and burn quickly. They can also release flammable gases that may support further combustion in a fire. Common building materials, such as wood, plastics, and wood composites are all combustible. It is not a good idea to use combustible materials on the exterior of a home located in an area that is susceptible to wildfires.


Materials like concrete, bricks, most metals and glass have been tested and deemed noncombustible. They are not known to ignite, burn or emit combustible gas during a fire and are therefore rated as noncombustible. For a fire-safe exterior, noncombustible materials will be the best choice.

Ignition resistance

This is a common designation for manufactured products such as roof shingles or treated lumber. It certifies how long it takes for them to ignite and how quickly flames spread during a fire. In order to ensure that ignition-resistant materials perform consistently over time, they must be subjected to accelerated weatherization. Although it can sometimes be used to describe building assemblies, ignition-resistant is often a designation for materials.

Fire resistant

This rating is often given to materials or assemblies that can contain fire and maintain structural integrity. It allows for time for occupants and firefighters to reach their destinations. The rating often comes with a time limit. For example, exterior doors may have a fire resistance rating of 20, 45 or 60 minutes, and 90 minutes for others.

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