Fire Prevention Terms

Permit Sonoma Fire Prevention

Definitions to commonly used fire prevention-related terms.

Defensible space
Defensible space is a buffer you create between the buildings on your property and any vegetation, such as grass, trees, or shrubs, that surround it. The defensible space area goes from building walls out for 100 feet, or to the property line, whichever comes first. Good Defensible Space can slow or stop the spread of wildfire, and can allow firefighters to safely defend your home.
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Structure Hardening

Structure Hardening addresses items on the building itself that can cause it to to catch fire from the blowing embers and heat of a wildland fire. Windblown embers cause 80% of home ignitions from wildfire. Ranging from the size of a grain of rice to a dinner plate, embers can blow into the building through openings like vents and ignite items inside the building, or pile up on flammable elements on or near buildings and grow into fires that can catch the building on fire.

Hardening the buildings means replacing or modifying structural elements that have been shown to cause home ignition. Specific changes may include replacing vulnerable elements like non-Class A roofs, replacing vents that will allow ember entry with Wildland/Urban Interface (WUI) compliant products; removing or modifying flammable attachments such as fences or decks, creating a 0 to 5 foot “non-combustible zone” near building walls, or replacing windows with double-paned WUI compliant panes.