Hardening Your Home Against Wildfire
Homes ignite from contact with flames or embers. Flying embers can destroy homes up to a mile ahead of a wildfire. Homeowners should "harden" their homes long before a fire starts.
A wildfire-safe home must be resistant to ignition from wind-blown embers. Even if the flames never reach your home, it must be able to withstand exposure to millions of tiny embers that can be carried 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 University of California publication, "Home Survival in Wildfire-Prone Areas: Building Materials and Design Considerations." The IBHS "Retrofit Guide" for California outlines regionally appropriate building features that can be easily retrofitted to existing structures to improve wildfire resistance.
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.
Embers are the most important cause of home ignition. Research indicates that two out of every three homes destroyed are ignited by wind-blown embers (Maranghides and Mell 2009) - 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 steps must be implemented: 1) the selection of building materials and designs that will help the home resist the wildfire; and 2) the creation of adequate defensible space, based on the selection, placement, and maintenance of vegetation within 100' of all structures.
Flying embers destroy homes up to a mile from the actual fire! Prepare (harden) your home now before a wildfire starts.
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.
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
Vents on homes create openings for flying embers.
- Cover all vent openings with 1/16" to 1/8" metal mesh as a minimum. Traditional 1/4" wire mesh openings are too large, and allow embers to pass. Vents with wire mesh AND baffles are best, or use vents marketed specifically as ember resistant and approved by the CA State Fire Marshal. Do not use fiberglass or plastic mesh.
- Protect vents in eaves or cornices with baffles to block embers. Mesh is not enough!
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.
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.
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.
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.
- 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.
- Install a battery backup to your garage door opener to ensure you can open and CLOSE it when evacuating, especially in the dark. Practice opening the door manually if you do not have a battery backup, since the power may be out when a wildfire approaches.
- Have a fire extinguisher and tools such as a shovel, rake, bucket, and hoe available for fire emergencies in your garage.
Consider using ignition resistant or non-combustible fence materials to protect your home during a wildfire.
Separate wood fences from buildings with a 3'-5' section of metal fence, or a metal gate, where they attach to the house.
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.
- 10' of horizontal clearance, using the same standards as the immediate zone of defensible space, are required along driveways and roadways adjacent to your property.
- Property owners are responsible for maintaining vegetation on their property, even if it is in the "right of way."
Make sure your address is clearly visible from the road.
- In California, 4" (minimum) address numbers on a contrasting background are required!
- Brass or bronze numbers will oxidize, and become difficult to read against a weathered wood background. Use white, stainless steel, or reflective numbers.
- Remember 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. Hoses should reach around building corners. If you have a swimming pool or well, consider installing a pump and a back-up generator.
- Fire Information Engine—Homeowner Wildfire Assessment
- University of California—Homeowner's Wildfire Mitigation Guide
- IBHS Home Retrofit Guide - California Edition
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:
- Home Landscaping for Fire. University of California Publication 8228. 2007. University of California, Davis.
- www.readyforwildfire.org. Wildfire is Coming: Are You Ready. CAL FIRE. 2012.
- Urban Forestry Associates. Ray Moritz, Urban Forester and Fire Ecologist.
- Protecting Your Home From Wildfire. 2017. Insurance Institute for Business & Home Safety,