Innovative solutions for creating healthy, efficient, eco-friendly homes

Creating a Fire-Resistant Home

Wildfires were particularly destructive last year, especially in the West, where thousands of homes were destroyed, and in the South, where drought left trees and shrubbery tinder-dry. Already this year, wildfires have sprung up in Virginia, the Carolinas, Florida, Texas, Colorado, Nevada and California, destroying homes and property.

Anyone who has watched a wildfire sweep across a landscape or through a neighborhood might wonder why some homes burn down to the ground while others are left untouched. In many cases, it’s because the homes that burned, and the landscapes around them, became fuel for the fires. The ones that survived didn’t.
“Wildfires burn through a lot of fuel,” says Michele Steinberg, Firewise Communities Support Manager for the National Fire Protection Association, based in Quincy, Mass. They consume low-growing plants as they spread along the ground and engulf taller plants and treetops, where they jump to other trees and to structures that provide more fuel.

By taking steps to make your home firesafe, you can limit the supply and accessibility of fuel on your property. Firesafe landscaping, also called firescaping, can slow wildfires down and may keep flames away from your home.

“Nothing will make a property fireproof, but there’s a lot of evidence that firesafing really works,” says Owen Dell, the Santa Barbara, Calif.-based landscape architect who coined the term firescaping. Using firesafe materials and construction methods gives your home a good chance of resisting the three types of danger from wildfires: flames, burning embers carried on the wind and radiant heat, which can ignite flammable materials.
Defending Your Home
Firescaping creates a defensible space on your property. In California, state law requires defensible space to extend to a distance of 100 feet from the home.

Begin by choosing plants suited to your climate. Plant them in groups according to their requirements for light, soil type and water. Next, create a landscape design that interrupts the paths that wildfires take. The best design consists of concentric circles or zones that radiate outward from the home. Plant in small beds or islands separated by wide paths of stepping stones, compacted soil, gravel or decomposed granite. If your property is on a slope, build retaining walls to reduce its steepness. The goal is to prevent a fire from burning along the ground.

To stop fires from leaping from groundcovers to taller plants to treetops, avoid laddering by keeping plants of similar heights together, and spacing taller plants farther apart than shorter ones. Plant trees so their canopies will be 10 feet apart at maturity, and away from power lines.

You can think of the landscape around your home in terms of zones. In Zone One, which is the 30 feet closest to your home, plant fire-resistant groundcovers and low-growing shrubs. However, “You don’t need to create a moonscape,” says Douglas Kent, a landscape architect who has been firescaping in Southern California since 1995. Use plants that have big, glossy, fleshy, waxy leaves. Irrigate to keep them moist but don’t overwater.

Many experts recommend using drip irrigation, but Kent advises soaker hoses on trees and shrubs, and overhead irrigation on groundcovers. Avoid grasses, as well as plants with fine leaves and hairs, high oil content or the tendency to accumulate dead leaves and stems. Keep propane tanks and firewood out of this zone.

Zone Two extends from 30 to 50 feet from the home. This should be a relatively open greenbelt zone. Plant drought-tolerant groundcovers and succulents, low shrubs, and larger shrubs and trees in widely spaced groups. Use drip irrigation.

Zone Three extends from 50 to 100 feet from the home. In this zone, plant larger native trees and shrubs, widely spaced and interspersed with lower plantings. Keep them thinned out, and don’t irrigate them once they’re established.

Some homeowners will have a fourth zone, which extends beyond 100 feet from the home. In this area, use native vegetation that has been thinned. However, for most homeowners, this area is their neighbors’ property. Firesafing is a community effort, experts say. When neighbors firesafe their own properties, everyone’s home is safer. “Houses are close,” Dell says. “We’re all in it together.”
Roofs, Walls and Windows
Although firescaping can help save a home, “the most important factor is how well the structure itself is defended,” Kent says. To make a home fire-resistant, homeowners should pay particular attention to materials used for the roof and exterior walls, as well as the home’s windows and doors.

The roof is critical in making your home firesafe. When flames are leaping from treetop to treetop, your home’s roof could be in their direct path. It’s also a perfect landing surface for firebrands, those burning embers carried on the wind.

Firebrands can land on the roof hours before a wildfire comes through and remain there long after it’s gone. If the roof is combustible or covered with leaves or pine needles, the embers can eventually grow into a fire, says Steinberg. “Consumers should look for Class-A roofing materials,” she notes. These materials aren’t fireproof but they can resist fire for two to four hours.

Concrete, slate and clay tile provide the best protection, but clay roofs need bird stops at the ends of the rows to prevent birds from building nests or embers from getting underneath. Some types of fiberglass-reinforced asphalt shingles are Class A-rated. Aluminum and copper, which are also Class-A materials, conduct radiant heat and require a sheathing underneath.

Exterior walls are susceptible to flames and to radiant heat from burning materials, including nearby vegetation, so they should always been underlain with solid sheathing. Fire-resistant siding materials include stucco, cement, plaster and concrete masonry like brick, stone and block. Metal is noncombustible but it conducts heat.

Although wood siding is combustible, it’s relatively resistant to flames if the wood is thick enough. However, it is susceptible to the long, slow radiant heat of a material burning nearby.

Windows are especially vulnerable to wildfires, Steinberg says. “Windows tend to fall out or crack, and the frame can ignite. Then flames or embers can enter the house.”

Double- and triple-paned windows are more fire-resistant than single-paned ones because they have more layers of protection, she notes. Although tempered glass is stronger than ordinary glass, dual panes provide more protection. In addition, smaller windowpanes are better than larger ones. They don’t break as easily, Steinberg says, and if they do break, they leave a smaller opening for flames to intrude.

Window frames have to be able to withstand fire. Wood and steel-reinforced vinyl frames provide better protection than unreinforced vinyl.

Shutters can provide some protection if they’re closed, says Steinberg. However, they’re expensive, and homeowners have to be home to close them when there’s a fire. “Shutters might be a good investment in a high fire-risk area, but they aren’t something we tell people to rely on,” Steinberg notes. Wood shutters protect windows from radiant heat but ignite under flames. Metal shutters don’t ignite but conduct radiant heat.

While metal screens don’t protect against flames, they do slow down ember penetration and absorb some radiant heat. Fiberglass screens are less effective.
Solid wood doors, because of their thickness, are effective fire barriers. However, other types of wood doors can burn through in 10 minutes. Metal doors are noncombustible, but again, they can conduct enough radiant heat to cause nearby material to ignite.

If the front door has windows, the panes should be small. Use good weather-stripping to keep hot gases and embers out of the house. Also, use fire-resistant doormats. “We’ve seen evidence that hemp and straw doormats are ember-catchers,” Steinberg says.
Vulnerable Areas
When building a new home in a fire-prone region, the placement of doors and windows is critical, Steinberg says. If they aren’t placed correctly, they can be exposed to the brunt of the flames. “One of the worst things you can have is large windows facing a lot of vegetation,” she says. “You have all that glass that’s vulnerable.” It’s worse when the vegetation is on a downward-facing slope, which often provides the best view and is exactly where homeowners would want large windows.

Other vulnerable areas include vents, chimneys and decks. “The vents are there for a reason,” Steinberg says. “They prevent the house from getting moldy.” They’re also invitations to flames and embers. All vents should be screened with corrosion-resistant mesh so flammable materials like debris and animals with nesting materials can’t get in, she says.

Experts often recommend enclosing vents with one-eight-inch mesh, but the small holes can become blocked by debris or even with house paint. If you use this size, make sure the holes in the mesh remain open. There’s some evidence that one-quarter-inch mesh is too large to keep firebrands out, but it’s better than no screening at all.

Chimneys are vulnerable as well. Embers can fall into a chimney and ignite a flammable object inside the house. To prevent this from happening, install a spark arrestor of welded wire or woven mesh.

Attachments to the home, such as decks, porches, exterior stairways, room pushouts and bay windows, as well as roofs of carports and patios, can trap heat and flames underneath. Enclose the undersides with non-combustible or fire-resistant screening. Eaves can cause problems for the same reasons. Use a noncombustible material to box them in, but be sure to allow for adequate ventilation.

Proper maintenance is the final step in firesafing your home. “You don’t want any cracks or openings into the house” where embers can infiltrate the house, Steinberg says. Check your house carefully, sealing all cracks and holes on the exterior before fire season begins.

Check your yard as well. Clear away leaves, pine needles and other debris from the area around the home, and from the roofs, eaves and gutters. Cover woodpiles and clear the vegetation surrounding them.

Prune trees to reduce twiggy growth and maintain separation between trees. Have professionals trim tree branches away from power lines. Remove weak, dead and diseased plants and branches. Mow grasses to about three inches high. Thin overgrown vegetation.

Homeowners can find more information on the websites of their local fire department or state forestry agency. “You can win this battle,” Kent says.