No home is entirely protected against wildfire. Most have at least a few weaknesses, a few materials or openings that make them vulnerable to flying embers or to the intense heat of wildland firestorms.
Reducing this risk channels attention to a few fronts. Creating a 30’-50’ “fuel free” zone around a dwelling is mandatory: key steps to implementing this strategy are pruning up and thinning out trees; changing decks, trellises, fences, patio furniture and other flammable outbuildings to non-combustible materials; and removing all plant dead wood, wood piles and other easily ignitable materials. Stone, tile or concrete patios, metal or masonry fences, tube steel trellises and cementitious sheds near the house are worthy choices.
Shifting attention to the house, avoid wood or vinyl siding (susceptible to melting in high heat). Fiber-cement siding is a good choice, preferably with tongue-and-groove rather than shiplap joints. Stucco is also an excellent non-combustible covering option. Both materials have the added advantages of being rot and rodent proof, low maintenance, requiring infrequent or no painting.
Roofs need to be constructed with non-flammable underlayment on top of plywood sheeting, which is better than oriented strand board, a composite material commonly used. Superior roofing materials are tile, metal, cementitious composites and slate. Stay away from wood shingles or shakes, even when treated with fire retardant. Don’t forget to clean gutters regularly to maintain fire safety.
Double pane windows perform far better than single pane in resisting sudden spikes in temperature during wildfires and impact from wind-driven flying firebrands. Such spikes often cause window blowout. Smaller panes survive better than bigger ones. Wood, wood clad with aluminum, metal and fiberglass frames all perform well—certainly better than vinyl frames. All exterior doors should have a one hour fire rating.
Selecting high performance foundation, eave and attic vents is critical for creating a fire-resistant dwelling shell. Soffit and attic vents can be eliminated by using icynene insulation (an open cell foam) on the underside of the roof, the only code-approved way to do so. In homes with crawl spaces, foundation venting is required by code for moisture control. Baffle vents, auto-closing vents and 1/8” screened vents are recent developments specifically designed to protect vent openings from heat and embers. In wildfires, there are hundreds of thousands of flying embers driven far ahead of the fire front by strong winds. Most are small and go out immediately. The larger ones can get pushed into any opening in the house shell, where they can smolder for hours, until possibly igniting nearby combustible materials and burning the house down.
Wildfires are important to the health and beauty of natural landscapes. Their periodic pattern reduces fuels, recycles nutrients, regenerates plants and stimulates biodiversity. We cannot “fireproof” forests, grasslands or shrub lands that depend on fire, but we can design, build and remodel homes to be more fire resistant.