Fire-Resistant Building Materials: 9 Ways to Build a the Most Fire-Resistant Home

Wildfires have destroyed about thousands of homes annually in recent years, according to the National Fire Protection Association, and other estimates suggest the past decade has been the most destructive.

In California, for example, 14,000 homes burnt to the ground in two enormous wildfires in 2018, resulting in nearly $19 billion in damages. There is growing concern that a pattern of rising temperatures and less rain is here to stay, further exacerbating the problem with wildfires and leaving billions of dollars of real estate in danger. As fire season gets longer and more destructive each year, it’s estimated that by 2039, about 11 states could see a 500 percent increase in the amount of land that’s burned each year.

As homeowners in fire-prone states pick up the pieces and rebuild, they no doubt wonder if it’s possible to reconstruct a home that will survive another inferno.

While it’s impossible to build a completely fireproof home, there are many precautions you can take to make your home as fire-resistant as possible. Here’s a step-by-step look at the measures you can work into your building plan and the materials you should use to protect your home against raging wildfire.

Rely on ICFs for Your Foundation

Ask any homebuilder about building a fire-resistant home, and they’ll point to insulated concrete forms (ICFs) as a key component in your home’s construction. ICFs are polystyrene blocks that connect together like pieces of Lego to create your home’s shell, locking out sound and weather.  They’re made up of concrete, making them one of the most fire- and heat-resistant construction materials around.

On the whole, concrete is an excellent material to work with when constructing a fire-resistant home. It’s non-combustible, it takes a long time for heat from a fire to damage its structure and load-bearing ability, and it stops fire from spreading.

Experts suggest ICFs can withstand fire for a maximum of four hours. They’ve conventionally been used in the construction of commercial and institutional buildings but homebuilders are starting to use ICFs now too. ICFs cost about 1 to 4 percent more than typical wood frame houses without built-in fire protection. However, this extra cost is worth the investment, as ICFs lock in heat and cooled air, which can escape through the walls. For this reason, ICFs are a go-to measure for many Energy Star-rated homes.

Armor Your Roof

Ensuring you have a fire-resistant roof is critical – while having a concrete structure is a great preventive measure, you’ll need to pair it with roofing, siding, and windows that are fire-resistant, too.

While West Coast architecture leans towards stylish Spanish tile rooves, the style is notorious for cracks and openings that allow embers to sneak into and start another flame. You can construct a fire-resistant roof using Class A, fire-rated materials that interlock tightly – think metal, concrete, slate, and tiling – and built over top a fire-resistant cap sheet for double duty protection.

It’s worth noting that a steeper roof pitch fares better than a flat one because embers roll off your home before they can burn through.

The sight of a looming blaze of fire can be intimidating but flying embers, about the size of a hand, pushed along by wind are usually the culprit behind 90 percent of fires spreading. Embers can fly up to seven miles from a wildfire, ending up in gutters and smouldering for hours before starting a secondary fire. For increased safety, choose metal gutters over vinyl, which could melt and drop fire onto the sides of your home. Always keep your gutters clean, too – dead leaves are tinder waiting to ignite.

Choose Sturdy Siding

Building a fire-resistant home doesn’t mean you have to sacrifice aesthetic. This applies to all aspects of your home’s exterior, right down to the siding.

You have many materials to choose from such as stucco, stone, brick, interlocking tiles, concrete blocks, fiber cement, or metal for siding – all of which can be designed in any architectural style in consultation with your builder and architect.

Remember the sturdy brick home from The Three Little Pigs? There’s some wisdom there: bricks are made in a fire kiln, so they’re already incredibly resistant to fire. A brick wall receives a fire-resistance rating of about one to four hours, depending on how it’s constructed and the thickness of the wall. Stucco is made of cement, sand and lime, and is also durable, fire-resistant, and usually includes a few coats of metal reinforcing mesh.

Steer clear of untreated wood shingles or planks, though, which are the least fire-resistant. Vinyl siding may be alright as long as a potential fire can’t find any gaps or crevices under the vinyl to come into your home.

South Carolina researchers pitted a traditional home built with wood shingles next to a fire-resistant home made with fire-resistant materials, and exposed them both to flying embers and heavy winds. Unsurprisingly, the home constructed with wood caught fire while the other didn’t.

When constructing the sides of your home, you need to pay special attention to the underside of overhangs and underneath your balcony, deck, and any other underfloor area. These are areas of your home where flames will be trapped and where the hottest temperatures will be in the midst of a blaze. Because of this, you need to focus on the structural integrity of these parts of your home with extra layers of protection, such as adding a perimeter of crushed stone or a firewall.

Protect Your Windows

Windows are the weakest link in your house, as they offer a fiery inferno a potential opening into your home. Extreme heat alone is enough to shatter glass or trigger combustibles inside your home without the blaze even entering your house.

Because of these concerns, your best bet is to choose insulated double glazing with tempered glass on the exterior instead of single glazing, which isn’t as sturdy in the face of fire or other natural disasters.

In the South Carolina study, single glazed windows cracked from the blaze and exposed the home to the fire. Double glazing will take twice as long to break at the hands of a wildfire, with the outer layer breaking first; tempered glass is heat-treated making it about four times stronger.

You can also look into wire glass or fire safety glass, which holds together even when it’s cracked by heat.  When it comes to size, smaller window panes fare better than larger ones.

When framing your windows, experts suggest that steel framing is the most flame-resistant option, followed by aluminium, with vinyl as the least resistant. If possible, opt out of an acrylic skylight, which could be susceptible to melting, leaving a hole in the roof.

The safest option, though, is to install roll-down metal fire doors from your roof overhang or along the side recesses that can be automatically released and secured with a latch – they’ll protect all windows and doors and act as an important extra layer of defense protecting your home.

Use Metal or Fiber-Cement for Doors

Doors act as another access point into your home for wildfires, so you’re better off not choosing wood doors, which usually offer only about 20 minutes of fire protection. Instead, doors with a metal core (and covered in any material you’d like) or fiber-cement can stave off a fire for much longer.

Garage doors are a key access point too – metal panel doors are your best bet again, but you’ll need to make sure these doors are very tightly fitted to prevent embers from sliding under.

Consider Your Layout

Strategize with your builder to maximize the distance between your home and the wildlands nearby, using your driveway, patio, low-growing fire-retardant plants, and fire-resistant materials as multiple layers of defense to buy you time as a wildfire approaches. Remember when planning: Wildfires typically blaze through faster on an uphill incline compared to ground level.

Your driveway needs to be wide enough for firefighters to park, move, and reverse their fire truck, while still being able to haul their equipment up to your home. In high stress times, it can be chaotic for firefighters to move a fire truck out of a narrow passageway, so it’s in your best interests to consider these logistics now and make it easy for them to navigate and do their jobs. You can also strategically place exterior lights on your roof so your home is clearly visible and easy to find for firefighters.

Don’t Forget About Backyards and Landscaping

While you’re swept up in the foundation of your home, the windows, roofing, and side panels, careful thought needs to go into your back and front yards, too.

Wood decks in the backyard have a bad reputation for fueling wildfires and bringing them right to your home’s doorstep. When possible, use composites, which will spread fire less quickly, or make sure the wood is treated with fire-resistant coating. Protect the underside of your deck with metal screening to keep the fire out. Instead of a typical wood deck, you can look at landscaping and concrete materials to build a terrace as a second option as well.

The same goes for wood fencing – they can act as an incendiary, so it’s wiser to create a fire-resistant barrier using stones or other masonry around the house.

While gardening, try your best to keep dead and highly flammable vegetation at bay so they don’t fuel the flames. In the experiment conducted by home safety experts, homes lined in mulch fared much worse in the face of a wildfire compared to a fire-resistant home lined with rocks. The fire-resistant home also kept plants at least five feet away from the home instead of hugging the home’s exterior. The researchers called this outdoor space a “non-combustible zone.”

Water and Power Generation

You can install sprinkler heads on the roof, patio or deck that turn on automatically to help stave off a looming fire. Advanced technology means you can even program the sprinklers so that once the firestorm has passed, the sprinkler systems can move on to putting out remaining spot fires along the roof and other exterior surfaces.

Prepare for the worst and assume that your home will lose electricity and water pressure. You’ll need a portable generator that will automatically kick in during an emergency.

Factor in the Investment Costs

The good news is overall, fire-resistant homes aren’t more expensive than traditionally-built homes.  A 2018 study by Headwaters Economics and the Insurance Institute for Business and Home Safety found that strategically designing homes to withstand wildfires is very cost-effective.

Adding a fire-resistant roof and metal gutters added $6,000 to the price tag while double glazed windows and a fireproof door increased the cost by about $5,000. However, fiber-cement siding was far cheaper than cedar wood planks offsetting the extra costs in the other categories.

Comparing the standard way of building a home using traditional materials with following fire safety code and fire-resistant materials, the team found that any additional expenses are offset by cheaper materials for other parts of the home. And, of course, the added peace of mind is priceless.