What is Defensible Space?

Defensible space is essential to improve your home’s chance of surviving a wildfire. It’s the buffer you create between a building on your property and the grass, trees, shrubs, or any wildland area that surrounds it.

Defensible space is intended to slow or stop the spread of wildfire and protect your home from catching fire – either from direct flame contact or radiant heat. Understanding how fire spreads is the central concept behind defensible space. Often understood as a “fuel ladder,” fire will spread vertically and horizontally where there is fuel available. The spacing between grass, shrubs, and trees is crucial to reducing the spread of wildfires. The spacing needed is determined by the type and size of brush and trees, as well as the slope of the land.

For example, a property on a steep slope with larger vegetation requires greater spacing between trees and shrubs than a level property that has small, sparse vegetation.

Creating an area of defensible space does not mean you need a ring of bare dirt around your home. Through proper planning, you can have both a beautiful landscape and a fire-safe home.

Defensible Space General Requirements

• Cut grass to no higher than 4”
• Limb up trees to 6 feet off the ground
• Cut bushes, shrubs, and trees so they are separated and don’t create a “fire fuel ladder”
• Maintain vertical clearance over roadways to 15 feet and 3 feet back on each side
• Maintain roofs and gutters free of dead leaves and pine needles

Please view our WUI Resources page, or you can always call us at 650.558.7600 and ask for our Fire Prevention Division for assistance.