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Home Hardening Video Series: Defensible Space

Clearing the vegetation and other flammable material around your home increases the likelihood that it will its survive a wildfire.

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Before you start creating your defensible space you might want to watch our video on Environmentally Friendly Pruning and Thinning Techniques. Proper pruning will result in healthier plants and healthy plants are more resistant to fire.

Creating Defensible Space

Creating Defensible Space means designing and maintaining the space around your home (and other structures on your property) to both reduce fire danger to the structure and to create a space from which first responders to a wildfire can safely defend your home. These two complimentary benefits can substantially increase the odds that your home can survive a wildfire.

A good defensible space will act to slow the spread of fire as it nears you home and work to ensure that embers from distant flames that land near your home do not find sources for ignition.

A good plan for defensible space is to design the space around you home in 3 “zones.”

Zone Zero

Zone Zero is the first 5’ from your building, including any attached decks and also the first 6” of vertical space at the base of the building, where wind-driven embers can accumulate. The target for Zone Zero is to remove all flammable material. Up to 90% of ignitions from wildfires are caused by embers. Wind driven embers can accumulate around the base of structures causing ignition. You can substantially increase the odds of your home surviving by clearing the area of all potential sources of fire fuel.

In addition to the Zone 1 targets, material that you should remove from this zone includes mulch, woodpiles, combustible trellises, and stored items. Zone Zero is an excellent location for walkways, or hardscaping with pavers, rock mulch, or pea gravel.

The following breakdown of steps to take in Zones 1 & 2 is borrowed from CAL FIRE

Zone 1

Zone 1 extends 30’ from buildings, structures, decks, etc. (i.e. another 25’beyond Zone 0).

  • Remove all dead plants, grass and weeds (vegetation).

  • Remove dead or dry leaves and pine needles from your yard, roof and rain gutters.

  • Remove branches that hang over your roof and keep dead branches 10 feet away from your chimney.

  • Trim trees regularly to keep branches a minimum of 10 feet from other trees.

  • Relocate wood piles to Zone 2.

  • Remove or prune flammable plants and shrubs near windows.

  • Remove vegetation and items that could catch fire from around and under decks.

  • Create a separation between trees, shrubs and items that could catch fire, such as patio furniture, wood piles, swing sets, etc.

Zone 2

Zone 2 extends 100 feet out from buildings, structures, decks, etc.

  • Cut or mow annual grass down to a maximum height of 4 inches.

  • Create horizontal space between shrubs and trees.

  • Create vertical space between grass, shrubs and trees.

  • Remove fallen leaves, needles, twigs, bark, cones, and small branches. However, they may be permitted to a depth of 3 inches.

Plant and Tree Spacing

The spacing between grass, shrubs, and trees is crucial to reduce 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.

Vertical Spacing

Remove all tree branches at least 6 feet from the ground.

Allow extra vertical space between shrubs and trees. Lack of vertical space can allow a fire to move from the ground to the brush to the treetops like a ladder.

To determine the proper vertical spacing between shrubs and the lowest branches of trees, use the formula below.

Great resources for finding out more about Defensible Space are:

https://defensiblespace.org/

Defensible Space