Hardening Your Home Against Wildfire
A wildfire-safe home must be an ember-ignition-resistant home, so that even if the flames do not reach your home, it will be able to withstand exposure to embers that may have been blown a mile or more in front of a wildfire. To provide maximum wildfire protection for your home, a combination of near-home vegetation management, appropriate building materials, and related design features must be used. These points are summarized the excellent Univesity of California publication, "Home Survival in Wildfire-Prone Areas: Building Materials and Design Considerations."
Preparing and maintaining adequate defensible space will guard against flame contact and radiant exposures from nearby vegetation—but because of the likely ember exposure to your home during a wildfire, you cannot ignore building material and design considerations. Similarly, if you ignore your defensible space (i.e., you do not have it or do not maintain it), the wildfire will produce maximum ember, flame, and radiant exposures to your home. It is very unlikely that even hardened buildings can survive such exposure, as a weak link will likely exist somewhere in the building enclosure.
There is a direct link between home survival, the vegetation management required in developing adequate defensible space around the home, and the building materials and design used to construct the home. The area where your vegetation should be managed (i.e., your defensible space) will depend on the particular topography and siting of the home on the property. Information included in this publication is focused on the home and is intended to provide information to help you make “fire wise” decisions regarding material choices and design decisions, whether you are building a new home or retrofitting your existing house. A considerable amount of information has been published in recent years on defensible space and vegetation management. Check with your local cooperative extension office or fire department for information appropriate to your area.
Here are some of the things you can do to harden your home:
Embers are the most important cause of home ignition. Recent research indicates that two out of every three homes destroyed during the 2007 Witch Creek fire in San Diego County were ignited either directly or indirectly by wind-dispersed, wildfire-generated, burning or glowing embers (Maranghides and Mell 2009) and not from the actual flames of the fire. These embers are capable of igniting and burning your home in several ways. In order to have a wildfire-safe home, two equally important factors must be implemented: 1) the wise selection of building materials and designs that will help the home resist the wildfire; and 2) the home must have adequate defensible space, based on the wise selection, placement, and maintenance of near-home vegetation.
Flying embers destroy homes up to a mile from wildland areas. Prepare (harden) your home now before fire starts.
Learn more about wildfire embers
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
Eaves and soffits should be protected with ignition-resistant* or non-combustible materials.
Screen or enclose rain gutters to prevent accumulation of plant debris
Learn more about fire resistant roofs
Heat from a wildfire can cause windows to break even before the home ignites. This allows burning 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.
Learn more about fire resistant windows
Walls and Siding
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.
Learn more about fire resistant siding
Surfaces within 10 feet of the building should be built with ignition-resistant*, non-combustible, or other approved materials.
- Ensure that all combustible items are removed from underneath your deck.
Learn more about fire resistant decks
Use the same ignition resistance materials for patio coverings as a roof.
Cover your chimney and stovepipe outlets with a non-combustible screen. Use metal screen material with openings no smaller than 3/8 inch and no larger than 1/2 inch to prevent embers from escaping and igniting a fire.
Have a fire extinguisher and tools such as a shovel, rake, bucket, and hoe available for fire emergencies.
- Install weather stripping around and under the garage door to prevent embers from blowing in.
- Store all combustible and flammable liquids away from ignition sources.
Consider using ignition resistant or non-combustible fence materials to protect your home during a wildfire.
Driveways and Access Roads
Driveways should be built and maintained in accordance with state and local codes to allow fire and emergency vehicles to reach your home. Consider maintaining access roads with a minimum of 10 feet of clearance on either side, allowing for two way traffic.
- Ensure that all gates open inward and are wide enough to accommodate emergency equipment.
- Trim trees and shrubs overhanging the road to allow emergency vehicles to pass.
Make sure your address is clearly visible from the road.
- In California, 4" address numbers on a contrasting background are required!
- Brass or bronze numbers will oxidize, and become difficult to read against a weathered wood background.
- Rememeber that firefighters may need to locate your home quickly at night, during storms, or in smoky conditions.
- Illuminate your numbers if possible and place them where they can be seen from the road by emergency vehicles travelling in both directions.
Consider having multiple garden hoses that are long enough to reach all areas of your home and other structures on your property. If you have a swimming pool or well, consider getting a pump and a back-up generator.
Fire Information Engine—Homeowner Wildfire Assessment
University of California—Homeowner's Wildfire Mitigation Guide
Fire Resistant Building Materials Video
Fire Safe Building Materials - a class with Steve Quarles
*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 “noncombustible materials” that don’t burn, exterior grade fire-retardant-treaded wood lumber, fire-retardant-treated wood shakes and shingles listed by the State Fire Marshal (SFM) and any material that has been tested in accordance with SFM Standard 12-7A-5.
The information contained on this page is derived from several print and online sources:
- University of California Publication 8228. Home Landscaping for Fire. 2007. University of California, Davis.
- http://www.readyforwildfire.org/ Wildfire is Coming: Are You Ready. CAL FIRE. 2012.
- Urban Forestry Associates. Ray Moritz, Urban Forester and Fire Ecologist.