CDF Bulletin - Make Your Home FireSafe



In January 2005, a new state law became effective that extended the required defensible space clearance around buildings and structures. Property owners are required to clear and maintain a Defensible Space Zone and a Reduced Fuel Zone, which when combined, extend 100 feet around any structure or to the property line, which ever is nearest. Proper clearance of the extra 70 feet dramatically increases the chance of your home surviving a wildfire. It also provides for firefighter safety when protecting homes during a firestorm. CDF recognizes that the new law is a significant change and as a result, full compliance within the Reduced Fuel Zone will not be required until June 1, 2007. It is highly suggested that homeowners begin reducing fuels in this zone now. As in the past, compliance within the Defensible Space Zone will continue to be required. The following guidelines explain what is required under the Public Resource Code (PRC) 4291 to achieve a Defensible Space and Reduced Fuel Zone.

Defensible Space Zone (0-30’ from any structure)

  • Maintain a firebreak around any building by removing and clearing away all flammable vegetation or other combustible growth. This does not apply to single specimens of trees that are well-spaced, well-pruned, and create a condition that avoids spread of fire to other vegetation, as well as ornamental shrubbery, or similar plants which are used as ground cover.
  • Maintain the roof and gutters free of leaves, needles, or other dead vegetative growth.
  • Remove that portion of any tree which extends within 10 feet of the outlet of any chimney or stovepipe.
  • Maintain any tree adjacent to or overhanging any building free of dead or dying wood.
  • Provide and maintain a screen, constructed of non-flammable material with openings of not more than one-half inch in size, over the outlet of every chimney or stovepipe.

Reduced Fuel Zone (30-100’ from any structure)

  • To achieve defensible space while retaining a stand of larger trees with a continuous tree canopy within the 30’ to 100’foot zone, apply the following treatments:
  • Generally, remove all surface fuels greater than 4 inches in height. Single specimens of trees or other vegetation may be retained provided they are well spaced, well pruned, and create a condition that avoids spread of fire to other vegetation or to a building of structure.
  • Remove lower limbs of trees (“prune”) to at least 6 feet or up to 15 feet (or the lower 1/3 branches for small trees). Properties with greater fire hazards, such as steeper slopes or more severe fire danger, will require pruning heights in the upper end of this range.
  • In certain fuel types (i.e. mountain misery), it may be impractical to remove live surface fuels exceeding 4” in height in the Reduced Fuel Zone. When this condition exists, live surface fuels exceeding 4” inches in height may be retained, however all trees shall be limbed or pruned to a minimum of 15 feet. Small trees (those under 30’) shall be limbed to a minimum of 50% of tree height. Single specimens of brush or shrubs may be retained, provided they are well-spaced, well-pruned, and create a condition that avoids spread of fire to other vegetation or to a building of structure.
  • Groups of vegetation (numerous plants growing together less than 10 feet in total foliage width), may be maintained in areas where surface fuels exceed 4” in height. However, all surface fuels adjacent to these groups shall be removed in accordance with the minimum horizontal spacing as established in the “Plant Spacing Guidelines” listed in the following table.

“Horizontal Plant Spacing Guidelines”

Guidelines are designed to break the continuity of fuels and be used as a rule of thumb for achieving compliance with PRC 4291

Tree minimum horizontal space from one tree canopy to the edge of the next

Slope Spacing

0% to 20%

10 Feet

20% to 40%

20 Feet

Greater than 40%

30 Feet

Shrub minimum horizontal space between edges of shrubs

Slope Spacing

0% to 20%

2 times the height of the shrub

20% to 40%

4 times the height of the shrub

Greater than 40%

6 times the height of the shrub

Vertical Spacing Guidelines

Minimum vertical space between top of shrub and the bottom of lower tree branches:
“3 times the height of the shrub”

  Slope Guide




If you have any questions please contact your local CDF Fire Station or the CDF Fire Prevention Bureau at 209-754-3831

 You are invited to attend the next

Highway 108 FireSafe Council Community Meeting.