Structures can also be protected by modifying the landscape surrounding them.  Reducing the risk of wildfire in the area surrounding a structure is known as creating a defensible space. This space is designed to make it more difficult for a fire to reach a structure in the first place.

When explaining how to establish and maintain a defensible space, use the zone concept.  Each zone encircles the structure to be protected. Zone 1 is closest to a structure and where the most mitigation measures are recommended.   Zones 2 and 3 are progressively further away.

Zone 1 extends at least 30 feet from the structure in all directions. Depending on the structure's risk, especially on any downhill sides of the lot, this zone may extend to 50 or even 100 feet. The objective of Zone 1 is to keep wildfire fuels at a minimum and have a source of water readily available.

Ideally within Zone 1:

  • Plants are very low to the ground and placed at least 3 feet from the structure
  • There are no outbuildings or trees
  • Branches from trees outside this zone do not reach within 10 feet of a roof
  • Mulch consists of fire resistant stone, lava rock, or similar material
  • Paths and walkways are made of stone, brick, or concrete
  • Decks and patios are made of non-flammable materials
  • Irrigation is provided by a sprinkler system or hose

(Illustration shows home in Zone 1 (extending 30 feet from the structure in all directions.)

Zone 2 begins where Zone 1 ends. The size of Zone 2 depends on specifics of the property such as the slope of the ground where the structure is built. It is acceptable to have small shrubs and trees in this zone.

Ideally, in Zone 2:

  • Trees, when fully grown, are no higher than their distance from the structure.  This prevents falling trees from landing on the structure during a wildfire
  • Trees are planted at least 10 feet apart
  • Branches on trees taller than 18 feet are trimmed to be 6 feet above the ground, to minimize ladder fuel on lower branches
  • An irrigation system is installed, if possible

(Illustration shows home with Zone 1 and Zone 2 pointed out. Zone 2 has trees that, when fully grown, are no higher than their distance from the structure.)

Zone 3 extends beyond Zone 2 as far as possible. This is a slightly modified natural area.  The objective in this area is to thin trees and remove all dead or dying vegetation that could become fuel for the wildfire.

There are other simple, inexpensive, yet very effective mitigation measures for making a defensible space more secure.  These include:

  • Keeping lawns maintained, leaves raked, and debris to a minimum
  • Storing flammable products such as paint thinner, kerosene, or gasoline, in metal containers in a storage shed outside of Zone 1
  • Keeping gutters and soffits free of leaves and debris
  • Keeping a garden hose that is long enough to reach all areas of Zone 1
  • Removing all flammable items, such as door mats, wooden chairs, and seat cushions from decks and entries

Simple actions like these can greatly improve the effectiveness of each zone.

(Illustration shows home with Zones 1-3 pointed out. Zone 3 is the furthest from the home.)