The Housing Scene

Wildfire Risk May Be Greater Than You Think

Wildfires like those that engulfed many areas in the Western states this summer can't be prevented, for the most part. But there's plenty homeowners can do to protect their properties.

And don't think you shouldn't be bothered: About a third of all houses in the United States are located in what fire safety officials call wildland urban districts, which are near or among areas prone to wildfires. According to the latest Natural Disaster Housing Risk Report from RealtyTrac, moreover, 13 percent of all single-family houses -- some 10.6 million houses and condos -- are located in counties with a "high" or "very high" risk for wildfires.

Over the years, wildfires have ravaged houses in three-fourths of the states. And with more and more people choosing to reside farther from urban centers and closer to nature, the chances are greater than ever that someone you know -- maybe even you -- will lose a house to fire.

Already this year, more than 45,000 fires have burned some 8.6 million acres, according to the latest count by the National Interagency Fire Center in Boise, Idaho. The majority of those fires have been in the West, but fires have raged practically everywhere.

For example, the worst drought in North Carolina history set the stage for an awful wildfire in 2008, when a lightning strike ended up scorching 41,500 acres. In Georgia a year earlier, nearly 470,00 acres burned and 26 structures were lost in that state's worst fire. And in Florida in 1998, 4,899 fires took out half a million acres and 342 houses.

Wildfires are covered by standard homeowner's insurance policies. But the best insurance is prevention. Here, gathered from a number of sources, are some steps you can take to protect your house and improve its fire resistance.

-- Choose a firewise location. Canyons may offer a beautiful view, but they tend to act as chimneys, drawing the fire up and accelerating the speed at which it spreads. A level site is better than a sloped one. A grass fire moves up a slope four times faster, with flames twice as high as a fire on level ground, because hot gases rising in front of the fire preheat the up-slope vegetation.

If you're building new, you can avoid this kind of topography. Also, find out about prevailing winds, seasonal weather conditions and the local fire history, so you can plan your landscape accordingly.

If your place is already up, go to work on your surroundings so the landscape will not bring a fire to your door. Do this by creating three safety zones, the extent of which will depend on your property lines and your risk. In high-risk areas, 200 feet away from the house may not be enough.

The first zone should be a well-irrigated area that circles the structure for at least 30 feet on all sides. If your house is on a slope, though, a clearance of between 50 and 100 feet may be necessary, especially on the downhill side of the lot.

Plantings in this area should be limited to carefully spaced indigenous species. Beware of "ladder fuels": vegetation that serves as a link between the grass and treetops and enables the fire to climb into trees or onto your house.

Trees and shrubs are fine in the first zone, as long as dead or low-hanging branches are removed promptly and the height of ground vegetation is controlled. But the more grass, the better, because a wide lawn can serve as a fuel break just as much as a driveway. Ditto for plants with a high moisture content.

Your irrigation system also should reach the second zone, which can contain a limited number of low-growing plants and trees spaced at least 10 feet apart. Dead or dying limbs should be trimmed away, and no live limbs should come within 10 feet of the structure. On trees taller than 18 feet, prune away branches that are less than 6 feet from the ground.

In zone three, thin selected trees and remove highly flammable vegetation such as dead or dying shrubs and trees.

-- Plan another line of defense. The survival space you construct around your house should keep all but the most ferocious wildfires at bay. But if one does happen to break through this protective zone -- usually from wind-blown embers or firebrands, sometimes more than a mile away -- ignition is most likely to occur on the roof.

Fire officials say eye-catching, untreated wood-shake roofs are the No. 1 cause of home losses in wildland areas because they can catch wind-blown sparks. If local rules allow, a better choice is factory-treated shakes. But consider using such noncombustible or fire-resistant roofing materials as Class A shingles; metal, cement and concrete products; or slate, metal or terra cotta tiles.

Fire-resistant sub-roofing also can improve survivability. But don't be fooled into thinking an expensive roof sprinkling system will stop a fire. You need a large volume of water to make a roof safe, yet water pressure is generally at its lowest during a fire. Also, the electricity needed to run the system is likely to fail, and the high winds that usually accompany a wildfire often divert the spray away from the roof.

Walls, too, should be made of fire-resistant materials such as stucco or masonry. Vinyl can soften and melt during a fire, offering little or no protection.

If you're building a new house, minimize the number and size of windows on the downhill side, the side most likely to be exposed to a fire. Smaller windows perform better than larger panes in high heat, according to the National Association of Homebuilders Research Center, and double-pane or tempered glass are each more effective than single-pane glass. For greater protection, windows, sliding glass doors and skylights should have nonflammable screening shutters.

To prevent sparks from entering your house, screen your chimney with noncombustible wire mesh. Also cover exterior attic and under-floor vents with wire mesh -- plastic or nylon screening will melt -- no larger than an eighth of an inch. Screen under your porch, too, as well as any other areas below the ground line.

Also, locate your under-eave roof vents near the roofline rather than near the wall to prevent heat or flames from becoming trapped inside. For the same reason, the eaves themselves should be boxed or designed with minimal overhang.

Finally, inspect your house occasionally, looking for breaks and spaces between roof tiles, warping wood or cracks and crevices in the structure where fire or sparks could enter.

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