Even in extreme winds and intense heat, some houses remain standing. Fire experts are discovering that homeowners can do a lot to increase a home’s chances of survival.
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Mario Tama/Getty Images/Getty Images North America
More than 10,000 homes have been destroyed in Los Angeles, with piles of charred wood and metal all that remains after the rapidly spreading wildfires.
But within this rubble, some houses still stand, apparently intact.
It is a phenomenon which been seen in other high intensity firessomething that may seem like a stroke of luck. Sometimes houses survived because the winds could have shifted at just the right time. But more often than not, fire experts find that these homeowners took essential precautions that likely saved their homes from burning down.
The main protective measures are measures that can be applied to the house itself, as well as to the environment directly surrounding it, including the density of flammable plants. Many requirements are already in California building codes regarding fire-prone areas and rules for clearing nearby brush and vegetation, known as creating “defensible space.” Some other Western states have adopted similar standards, even those that have experienced destructive wildfires.
Steve Hawks of the Insurance Institute for Business & Home Safety inspects a Pasadena home that withstood the Eaton Fire.
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In Los Angeles, fire experts are examining surviving homes, looking for clues about what worked, hoping to improve building standards and help prevent similar disasters.
Forensics for buildings
Steve Hawks is something of a forensic analyst. Not for crime scenes, but for buildings.
In Pasadena, it takes a narrow cul-de-sac where several homes were destroyed in the Eaton Fire, which consumed or damaged more than 7,000 structures. Hawks is here with a team from the Insurance Institute for Business & Home Safety, a nonprofit research group that studies how buildings burnfinanced by the insurance sector. After major fires, the group deploys to study how buildings behave in such extreme conditions.
He squints at a building that was once a detached garage, now a pile of blackened debris with only fragments of walls still standing.
“With the winds that pushed the fire that night, I’m sure the intensity was pretty high,” he said, scanning the charred hills above.
But nearby, the house stands, appearing largely unscathed. Hawks’ job is to try to understand why.
#1 Clearing vegetation that connects the house
Hawks retrieves a satellite image of the house before the fire, which shows the detached garage surrounded by greenery, the plants nestled up to the walls.
“So you can see some vegetation right up against that garage, which probably led to that structure igniting,” he says.
Wildfires often spread by embers, tiny burning debris that high winds can throw more than a mile. If embers land on a bush or tree, the fire can spread to new locations, even if surrounding homes don’t burn.
A teal home lies relatively unscathed behind a home destroyed by the Eaton Fire. An initial analysis of the Los Angeles fires found that brush and wooden fences helped spread fire from house to house.
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This is why Los Angeles rules requiring defensible spacerequiring trees to be cut back from the roofline and bushes to be spaced apart. Homes located in high-risk areas are subject to annual inspections to ensure homeowners are in compliance. The key is to make sure plants and bushes are not touching each other or the house, acting as a highway for flames.
“If a bush or an object catches fire, then we want it to be able to go out safely and not ignite the next one and the next one and the next thing you know, the fire is in the house,” Hawks said.
California is currently drafting rules that impose even stricter limits on vegetation directly next to the walls of a house. Studies show that plants growing within five feet of a structure significantly increase the risk of inflammation.
“Those first five feet are so critical,” Hawks says. “No combustible objects within the first five feet of the wall.”
#2 Put space between buildings
When this detached garage burned, it likely produced extreme radiant heat, reaching temperatures of several thousand degrees. This heat is enough to ignite nearby buildings. But in this case, the main house is located 30 feet from the garage.
“If that garage had been closer, it could have resulted in the loss of that structure,” Hawks says. “Our research indicates that ten feet or less is so close that when one ignites and burns, even good materials have difficulty withstanding such exposure.”
A flammable object burned at a Pasadena home, but because the siding is fire-resistant stucco, the flames did not spread to the house itself.
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An analysis by Hawks’ team found that where fire damage to the Palisades was most severe, more than half of the homes were less than 20 feet apart.
#3 Use fire-resistant building materials
While the house was spared, Hawks spots a burn mark on its exterior wall, appearing to come from something that was right next to the house that caught fire. But the flames did not ignite the rest of the house because its exterior is covered in stucco, not a more flammable material like wood.
The home’s construction materials check plenty of other boxes for the Hawks. The roof is fire-resistant, known as “Class A”, the gutters are metal, and the windows are double-glazed tempered glass, which is more resistant to shattering in high heat.
Even the smallest details can be important. Hawks points out the attic vents, just below the roofline, which are covered with chicken wire. If the screen openings are too large, embers can fly directly into a house and ignite it from the inside.
“So if you take a regular golf tee and try to put it through the mesh, if it goes through, it’s too big,” he says.
Inspectors say learning how building materials perform in extreme conditions can help improve housing codes in wildfire-prone areas.
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The surviving house is more recent. Hawks says the owner probably had to build it to comply with California building codes for wildfire zones, known as “Chapter 7a,” which mandate many of these features. Studies show that for new construction, the codes do not have to add significant cost. Older homes in the area often don’t meet these codes, but Hawks says renovations can still be done.
Every home that doesn’t burn during an extreme wildfire benefits the entire community, Hawks says, because it doesn’t produce heat or embers that can spread the fire to others.
“We’re not going to be able to stop fires from spreading in every community in every situation. So we need to prepare communities and that at the patch level,” Hawks said.
