Can you really use foil to fireproof your house?
Get the facts before wrapping your home.
Wildfires are spreading farther and wreaking more havoc than they have in recent memory. In an attempt to combat the flames, fire experts and ordinary civilians alike are turning to a flashy method of protecting historic trees and precious buildings: wrapping them in wildfire-resistant foil.
This technique isn’t new: fire departments in wildfire country have been using foil wrap for decades to protect structures like ranger stations, monuments, and remote US Forest Service buildings. But recent photos of houses miraculously intact amidst smoldering rubble have inspired some homeowners to take matters into their own hands—at times even shelling out big money for the same shiny wrapping material used by the pros.
The basics of DIY foil wrapping
Several homeowners have used protective foil to save their houses from being destroyed by wildfires in recent months. In late August, Eric Raymond successfully protected his cabin in the Twin Bridges, California area from the destructive Caldor Fire by covering it in thick aluminum foil he got from his employer, a vacuum valve manufacturing company.
Other homeowners have opted for a higher-tech approach: a few weeks after Raymond’s success, Martin Dikey spent more than $6,000 on fire-resistant wrapping foil laced with fiberglass and acrylic adhesive to save his second home, a wooden house on the California side of Lake Tahoe. This highly engineered material is the same stuff the Forest Service and National Park Service use to protect sensitive structures. But you can’t just go out and run a few rolls around your home.
“It is not easy to wrap a structure. To do it right, it takes quite a few people, and it has to be fastened correctly,” says Chad Cook, an assistant fire chief at the Ventura County Fire Department in Camarillo, California. He recommends that people only attempt this difficult and expensive process if three factors are all in their favor: access to the proper materials, the timing of the fire threat, and the conditions of the surroundings.
The proper materials
Wildfires produce three types of heat. The flames themselves give off radiant heat—that’s what you feel when standing close to a campfire. The fire also creates air currents, which carry convected heat, and can bring glowing hot embers along for the ride. Finally, conducted heat occurs when the flames touch something and burn it directly.
[Related: Forest fires leave behind charcoal, and it might be toxic for years]
Effective fire protection guards against all three types of heat. That’s why foil that has been specifically designed to withstand wildfire temperatures using layers of insulating material and a super-shiny outer coating is your best bet for wrapping a house or any other piece of property. Standard aluminum foil from your pantry—even the heavy-duty stuff Raymond used on his cabin—likely won’t cut it in serious wildfire conditions.
“The real issue with foil you would get in the grocery store is it would not stand up to the environment that is created by fire,” says Cook. “It’s too thin, too brittle.” While the shininess of regular aluminum foil can help deflect some of a fire’s radiant heat, it’s too flimsy to protect against convected and conducted heat.
If you’re willing to pay big bucks for proper wrapping material, you’ll also need a few other tools: at least one staple gun with lots of staples, foil tape, multiple ladders, and plenty of help from friends or professionals. Don’t attempt a major wrapping project unless you can get your hands on all of these items well before a wildfire arrives.
Foil wrapping usually involves stapling long sheets of wrapping material directly onto a structure’s exterior. These sheets must be properly overlapped and sealed with staples or foil tape to keep wind from prying them loose. Any vulnerability in this barrier could allow embers to sneak through the wrapping and ignite the building inside. This makes it a precise, laborious job that can’t be rushed.
“It takes longer than you think to apply structure wrap,” says Cook. “It is a feat to wrap a large house or a cabin.” He recalls participating in wrapping projects that took a team of firefighters more than 10 hours to cover a single building. And even with four professional contractors helping him, Dikey said his Lake Tahoe home took 12 and a half hours to wrap. For this reason, it is crucial to leave way more time to wrap a structure than you think you’ll need.
If you decide to embark on a wrapping project, heed local warnings about approaching fires and always prioritize personal safety over your possessions. Start as many days before the fire arrives as you can, and never ignore an evacuation order to wrap your home last-minute. If you don’t have enough time to completely cover your home well before danger arrives, you can still protect it by covering its windows, vents, and any other openings where embers could find their way inside. And if you can only cover one side of your house, choose the one with the most trees, grasses, vegetation, and debris nearby, Cook says.
The surrounding conditions
Isolated buildings in well-cleared, remote areas are the best candidates for foil wrapping. This is because organic material provides fuel for wildfires—and its absence can prevent the flames from lingering around your home. “The best measure you can take is to keep your property clean of fuel and debris,” says Cook. “You have to maintain the land… and keep growth to a minimum.”
[Related: California’s forest management isn’t the problem]
Even the toughest foil used by the pros is only meant to protect buildings for short periods of fire exposure—around five to 10 minutes—as a wildfire blazes through. This is why it typically isn’t used in residential areas, where nearby houses and other unprotected structures can provide hours of fire fuel. Starving a fire of trees, vegetation, fallen branches, and other natural debris can help foil wrappings shield your possessions more effectively.
So what if your home only has a few trees around it? Firefighters have successfully used structure wrap to protect ancient sequoia trees from burning by swaddling their bases in the material. You could do the same for the trees around your house, but Cook says the flames will likely just spread to the tops of adjacent trees, becoming a “crown fire” that travels between upper branches to reach your house. This means that it’s best to use foil to cover the most vulnerable parts of the structure itself, rather than the fuel sources around it.
Other protection methods
Overall, foil wrapping is only a good idea if you have optimal conditions. If a wildfire is definitely approaching but is still a few days away, and you’re willing to pay top dollar for the same sophisticated foil that firefighters use, and your property is in a remote location on well-cleared land, and you have a small army of people willing to help you, go for it. Just be aware that despite all these precautions, foil wrapping isn’t guaranteed to save your possessions.
If time, money, or logistics aren’t all on your side, Cook recommends exploring another last-minute protection option: flame-resistant gel. This sprayable substance is cheaper and easier to apply than foil wrapping, and can help insulate your possessions against all three types of heat.
“It sticks to the side of your home and it has a tremendous heat-absorbing capacity,” says Cook. “I have [even] seen people cover their automobiles with it.” He also recommends investing in a fireproof safe to store your most valuable possessions. That way, even if you can’t protect your home, the most important items within it still have a shot at survival.