By John R. Hawkins
Fire Chief & Operational Area Fire & Rescue Coordinator & William Weiser, Division Chief
Cal Fire/Riverside County Fire Department
The following excerpted information will be very valuable as you plan and act to create or maintain defensible space:
Defensible Space Zones
Two zones make up the required 100 feet of defensible space as stipulated in PRC 4291.
Zone 1 extends 30 feet* out from buildings, structures, decks, etc.
• Remove all dead plants, grass and weeds (vegetation).
• Remove dead or dry leaves and pine needles from your yard, roof and rain gutters.
• Trim trees regularly to keep branches a minimum of 10 feet from other trees.
• Remove branches that hang over your roof and keep dead branches 10 feet away from your chimney.
• Relocate wood piles into 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 extends 100 feet out from buildings, structures, decks, etc.
• Cut or mow annual grass down to a maximum height of 4 inches.
• Create horizontal spacing between shrubs and trees.
• Create vertical spacing 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 tree tops like a ladder.
Hardening your home: Flying embers can destroy homes up to a mile from a wildfire. “Harden” your home now before a fire starts by using ember-resistant building materials. Here are some things you can do to harden your home and make it more fire resistant.
The roof is the most vulnerable part of your home. Homes with wood or shingle roofs are at high risk of being destroyed during a wildfire. Build your roof or re-roof with materials such as composition, metal or tile. Block any spaces between roof decking and covering to prevent embers from catching.
Vents on homes create openings for flying embers. Cover all vent openings with 1/8-inch to 1/4-inch metal mesh. Do not use fiberglass or plastic mesh because they can melt and burn. Protect vents in eaves or cornices with baffles to block embers (mesh is not enough).
Eaves and soffits should be protected with ignition-resistant* or non-combustible materials.
Heat from a wildfire can cause windows to break even before the home ignites. This allows embers to enter and start fires inside. Single-paned and large windows are particularly vulnerable.
• Install dual-paned windows with one pane of tempered glass to reduce the chance of breakage in a fire.
• Consider limiting the size and number of windows that face large areas of vegetation.
• Wood products, such as boards, panels or shingles, are common siding materials. However, they are combustible and not good choices for fire-prone areas.
• Build or remodel your walls with ignition-resistant* building materials, such as stucco, fiber cement, wall siding, fire retardant, treated wood, or other approved materials.
• Be sure to extend materials from the foundation to the roof.
* Ignition-resistant building materials are those that resist ignition or sustained burning when exposed to embers and small flames from wildfires. Examples of ignition-resistant materials include “non-combustible materials” that don’t burn, exterior-grade fire-retardant-treated wood lumber, fire-retardant-treated wood shakes and shingles listed by the State Fire Marshal and any material that has been tested in accordance with SFM Standard 12-7A-5.
Editor’s note: Next week, Hawkins continues the details of preparing for wildfire.
John Hawkins is the fire chief for the Cal Fire Riverside Unit and Riverside County Fire Department. He is entering his 54th year with Cal Fire and has served as the fire chief for going on 11 years. Chief Hawkins values leadership, fire and life safety and community involvement. He has been involved with the Riverside County Mountain Area Fire Safety Task Force since 2004. He served as the Cal Fire IC at the 2003 Cedar Fire in San Diego County. The Cedar Fire remains the largest and most destructive in California history.