By Matthew Power. Tinder-dry forests and grasslands. Homes and communities built on the fringe of rural frontiers. When the next natural inferno makes its move, can your rural homes survive a fiery flashover? Take some of these special precautions in the building process and give your homes a fighting chance.
When wildfire swept through Bob Heath's neighborhood in Napa, Calif., a lot of other homes in the fire's path burned to the ground. Why not his?
"I had Cultured Stone all over the outside," notes Heath, (incidentally a vice president of marketing for Cultured Stone, a cementitious siding company). "The fire flashed right over it but did no harm. It caused just a slight discoloration in some places."
Which is not to say that his home--or any home--is entirely fireproof. But new research and anecdotal evidence suggests that homes built with the right materials, the right landscaping, and smart detailing have a far better chance to be left standing after a flashover event.
Builder influence
In recent years, as many as 2,000 homes (annually) have been destroyed by wildfire, a loss inflated by drought conditions in both eastern and western states, along with steady encroachment of development onto "frontier" lands. Jim Smalley, manager of wildland fire protection for the National Fire Protection Association (NFPA), notes that some home builders have taken an active role in fire prevention--often getting some perks in the process. The NFPA's Firewise program holds frequent meetings where builders can share ideas with fire experts.
"We had some New York builders who attended our workshops," he notes, "and they added a whole new level."
While "fire people" tend to focus primarily on the use of non-combustible materials, he explains, builders talk about changing the layout of lots or the way streets interact with properties. "Instead of homes on the side of the cliff, for example, they came up with a way to wrap the road around the crest below. That gives them more prime lots with great views, and a firebreak. We've actually seen it work in real fire situations." Of course, product choices still play a big part in fire prevention, but like so many other aspects of housing, they have to be considered as part of the whole package.
"We're especially interested in different kinds of materials for fences and decks," notes Smalley. "A lot of the new [composite] decking materials look promising, because they don't tend to burn the same way wood does. In many cases they appear to sort of fall apart and drop to the ground without further spreading the fire."
From the ground up
What's the incentive for builders to address wildfire risks? "They get a much better project out of it," asserts Smalley. "Rather than doing the design and trying to get it approved--only to have somebody say, 'You didn't take this into account,' you begin the whole process up front. You talk to land planners, national park people, the Nature Conservancy. You say, 'This is what we have in mind,' and collaborate on how to get there," he explains.
"Of course, the builder also wants to maximize profit," Smalley adds. "We have seen some builders using the fact that homes are in a Firewise community as a selling tool."
"We don't need to have an adversarial relationship with builders," he adds. "What we need is more collaboration. The problem has always been that we're interested in public safety and the builder is interested in making a living. We're now bridging that divide." He adds that home buyers need to shoulder personal responsibility for keeping their homes in accordance with fire-safe practices. "That means clearing leaves, cleaning gutters--they need to take personal responsibility," he says.
"Insurance companies don't offer special incentives for Firewise homes," Smalley adds. "That's because wildfire is so unpredictable. But we do know that all the big fires you see on TV aren't the ones that burn homes. It's the little bitty fires, the firebrands and embers that drop on the house from a mile away. Of the 200 homes that burned down in the Los Alamos fire, the majority were 18-inch flames--just ground fires that crept across people's lawns."
1. Stay detached
Keep in mind that many rural fires begin as vehicle fires. Also, outbuildings such as garages and storage sheds often contain flammable materials, such as paint thinners and gasoline. By keeping them detached and well separated (30 feet seems to be the preferred minimum) from the main house, a bigger loss may be prevented.
2. Upgrade glazing
As a general rule, insulated (double-pane) glass holds up longer than single pane when faced with the heat of a wildfire. Consider tempered glass. Sliding doors are tempered and insulated and have been found to withstand heat longer than standard plate glass. In general, smaller window panes survive better than big ones. Also, steer away from acrylic skylights. They can quickly melt and leave a gaping hole in the roof. Another good alternative if budget permits: Add non-flammable shutters similar to hurricane shutters.
3. Armor the roof
On the home's roof, install a Class A, fire-rated material, such as standing seam, tile, slate, or cementitious composite roofing. If you must use wood shakes, apply a good fire treatment but inform owners that the treatment is only good for a limited time (usually five years or so). A steeper roof pitch has much better fire resistance than a flat one. Burning embers roll off before they have time to burn through. Inform homeowners that they need to clean gutters to maintain fire safety.
4. Screen entry points
To keep flaming material from finding a way into the inner recesses of the home, critical areas should be covered with a 1/8-inch wire mesh. These include soffit vents, gable end vents, and even dryer vents. Be aware that nylon window screens may melt. Pay special attention to basement windows, where fire may be hottest and glass may break. Shroud chimneys with a 1/4-inch wire mesh but be sure to consult the manufacturer about proper tolerances--so as not to create a buildup of exhaust gases.
5. Armor the walls
For siding, specify non-flammable material, such as fiber-cement siding, Cultured Stone, brick, or stucco. Avoid untreated wood. Vinyl siding may be adequate if fire can find no route to burn too close to the house (it tends to melt and slough off), but all gaps and crevices beneath the vinyl must be sealed--or fire could find a way into the structure. To protect the base of the siding, where wood sills may overhang the foundation, consider putting a perimeter of crushed stone, so fire can't get a foothold adjacent to the house.
6. Plan decks with care
Wood decks often provide fuel for wildfires and ignite the house. If you do use wood, it should be treated against fire. Better yet, consider building with composites, which may spread fire less quickly. Also, look at concrete products and think about terracing and landscaping as an alternative to a traditional wood deck. Put metal screening around the crawlspace beneath the deck, to keep fire and embers out.
Perimeter Defenses
Site the home with wildfire burn patterns in mind. * Find the level. Wildfire generally moves faster uphill, with longer flames than on level ground. Rate of fire spread may double for every 20-degree increase in slope. Build at least 30 feet back from any ridge or cliff, on level ground if possible.
* Clear the fuel. Encourage the homeowner to maintain a "fuel-free" area of landscaping around the home. Keep dead or flammable vegetation well clear of outbuildings and the main house. Clear small shrubs and trees growing under larger trees. Space large trees at least 30 feet apart, and prune branches to a height of 8 to 10 feet. Place shrubs at least 20 feet from structures.
* Mind the fence. Flammable wooden fences can act like an incendiary fuse, leading flames directly to the house. Create a firestop of masonry between the house and the fence--or simply build the fence of masonry or metal components.
* Open the gates. For gated communities, be sure to include provisions for emergency override of any gate that might restrict fire trucks or emergency vehicles. Also, the subdivision should include two access roads, separated by significant distance.
Outdoor Fire Starters
Open Flame (e.g., matches, lighters, burners): 40%
Arson (Eastern U.S.): 29%
Arson (Western U.S.): 12%
Natural Causes: 9%
Other: 22% (approx.)
Hot spots: Exterior fires (those starting outside of structures) account for 45 percent of all fires in rural areas, (55 percent in the West, 36 percent in the East). They typically start in one of the ways described above. Fire-resistant construction can buy valuable time for rural homes, whether or not the source of the fire is natural or man-made.
