The concept of the home ignition zone was developed by USDA Forest Service fire scientists in the late 1990s, following experimental research into how homes ignite due to the effects of radiant heat. The primary goal for Firewise landscaping is fuel reduction — limiting the amount of flammable vegetation and materials surrounding the home and increasing the moisture content of remaining vegetation. The home itself and everything around it up to 100 – 200 feet is known as the ‘home ignition zone.’ In areas across the country where the risk of wildfire is high (here), the home ignition zone extends up to 200 feet beyond the actual home structure. Within this 200 foot area, there are three zones:
Zone 1 encircles the structure and all its attachments for at least 30 feet on all sides. In this area, plants should be carefully spaced, low-growing and free of resins, oils and waxes that burn easily. Mow the lawn regularly, and prune trees up six to ten feet from the ground. Trim back trees that overhang the house, and create a ‘fire-free’ area within five feet of the home, using non-flammable landscaping materials and/or high-moisture-content annuals and perennials. Remove dead vegetation from under deck and within 10 feet of house. Consider fire-resistant material for patio furniture, swing sets, etc. Firewood stacks and propane tanks should not be located in this zone.
Zone 2 is 30 to 100 feet from the home, and plants in this zone should be low-growing, well irrigated and less flammable. In this area, leave 20 feet between individual trees. Encourage a mixture of deciduous and coniferous trees and create ‘fuel breaks’, like driveways, gravel walkways and lawns, and prune trees up six to ten feet from the ground.
Zone 3 is 100 to 200 feet from the home and in this area smaller conifers that are growing between taller trees and heavy accumulation of woody debris should be removed. Property owners need to address the “little things” first: NFPA advises property owners to start with the house and work their way out. Having a nonflammable roof covering and assembly adds an enormous safety measure. Keeping roofs and gutters clean and clear of leaves or needles is critical to minimizing ignition from embers. Flammable attachments are very vulnerable to ignition and can carry fire to the main structure. Clean out any leaves, needles or stored material that could burn from under decks or porches. During the high fire danger season, large potential heat sources such as piles of firewood, spare building materials, vehicles or anything that could catch embers and ignite by flames in the grass should be removed as far away from dwellings as possible.
The perimeter of the home and attachments out to about 5 feet is vulnerable if there is anything there that could ignite and thus allow flames to touch the house should be removed. Wind-driven fire will create a blizzard of embers that will pile up in corners where you might normally find accumulations of leaves or needles around your home. These corners, nooks and crannies should be clear of any flammables. If there are any limbs or branches overhanging the roof, or any branches close to/touching the house, trim back to at least 10 feet from the house.
Radiant heat ALSO causes homes to burn so adding hardscape to break up the path of flames will reduce this exposure. Vents or openings should be screened with fine metal mesh, and windows should be replaced with double or triple-paned alternatives or tempered glass. Embers and small flames are major culprits and experiments show that not only should the radiant heat exposure be mitigated in the home ignition zone, but exposure to embers and surface fire as well. In fact, all the research around home destruction and home survival in wildfires point to embers and small flames as the main way that the majority of homes ignite in wildfires. For that reason, NFPA recommends methods to prepare homes to withstand ember attack and minimize the likelihood of flames or surface fire touching the home or any attachments (fences, decks, porches) as the first place for homeowners to start working to prepare their properties.
Remember a wildfire can and will happen here and a small one in your yard can be just as tragic for you as the big ones you see on TV.
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For more information on the Firewise program, contact Frank Riley, Executive Director and Georgia Firewise Liaison, Chestatee-Chattahoochee RC&D Council @ firstname.lastname@example.org.