More than 10,000 houses have been destroyed in Los Angeles, the charred piles of wood and metal all that remains after the fast-moving wildfires.
But within that wreckage, some homes are still standing, seemingly untouched.
It's a phenomenon that's been seen in other high-intensity fires, something that can feel like a stroke of luck. Sometimes, the houses survived because the winds could have shifted at just the right moment. But more often, fire experts are finding those homeowners took key precautions that likely saved their houses from burning.
The key safeguards are things that can be done to the house itself, as well as the environment directly around it, including the density of flammable plants. Many are already requirements in California's building codes for fire-prone areas and its rules for clearing nearby brush and vegetation, known as creating "defensible space." Few other Western states have adopted similar standards, even those that have seen destructive wildfires.
In Los Angeles, fire experts are surveying the surviving homes, looking for clues about what worked, in the hope of improving construction standards and helping prevent similar disasters.
Forensics for buildings
Steve Hawks is a forensic analyst, of sorts. Not for crime scenes, but for buildings.
In Pasadena, he walks up a narrow cul-de-sac with several homes 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 non-profit research group that studies how buildings burn, funded by the insurance industry. After major fires, the group deploys to study how buildings fare in such extreme conditions.
He squints at a building that was once a detached garage, now a heap of blacked debris with only fragments of walls still standing.
"With the winds that were pushing the fire that night, I'm sure this was pretty high-intensity," he says scanning the charred hills above.
But nearby, the house is standing, looking largely unscathed. Hawks' job is to try to figure out why.
#1 Clearing vegetation that connects to the house
Hawks pulls up a satellite image of the house before the fire, which shows the detached garage surrounded by green, the plants nestled right up to the walls.
"So you can see vegetation right up against this garage, which likely led to the ignition of this structure," he says.
Wildfires are often spread through embers, tiny bits of burning debris that strong winds can cast more than a mile away. If embers land in a bush or tree, the fire can spread to new places, even if the surrounding homes aren't burning.
It's why Los Angeles has rules requiring defensible space, mandating that trees be trimmed back from the roofline and bushes be spaced out. Homes in high risk areas get yearly inspections to ensure homeowners comply. The key is to ensure the plants and bushes aren't touching each other and the house, acting like a highway for the flames.
"If one bush or item ignites, then we want it to be able to burn out safely and not ignite the next one and next one and the next thing you know, the fire's at the house," Hawks says.
California is currently drafting rules that will put even stricter limits on vegetation directly next to a house's walls. Studies show that plants growing within five feet of a structure dramatically increases the risk of ignition.
"That first five feet is just so critical," Hawks says. "No combustible items in the first five feet away from the wall."
#2 Putting space between buildings
As this detached garage burned, it likely produced extreme radiant heat, reaching temperatures in the thousands of degrees. That heat is enough to ignite nearby buildings. But in this case, the main house is sitting 30 feet from the garage.
"If this garage was closer, it could have led to the loss of this structure," Hawks says. "Our research is saying at ten feet or less, that's so close together that when one ignites and is burning, even good materials have a hard time withstanding that much exposure."
An analysis from Hawks' team found where the Palisades Fire damage was the worst, more than half the homes were distanced less than 20 feet apart.
#3 Using fire-resistant building materials
While the house was spared, Hawks spots a burn mark on its outside wall, appearing to be from something that was sitting right next to the house and caught on fire. But the flames didn't ignite the rest of the house, because its exterior is covered in stucco, not a more flammable material such as wood.
The home's building materials check a lot of other boxes for Hawks. The roof is fire-resistant, which is known as "class A," the gutters are metal, and the windows are made of double-paned tempered glass, which are better at resisting shattering in high heat.
Even the smallest details can matter. Hawks points to the attic vents, just under the roofline, which are covered in mesh. If the mesh's openings are too large, embers can fly directly into a house and ignite it from the interior.
"So if you take a common golf tee and try to poke it through the mesh, if it goes through, it's too big," he says.
The surviving house is a newer one. Hawks says the homeowner likely had to construct it to comply with California's building codes for wildfire areas, known as "chapter 7a," which mandate many of these features. Studies show that for new construction, the codes don't have to add a significant cost. Older homes in the area don't often meet these codes, but Hawks says retrofits can still be done.
Every house that doesn't burn in an extreme wildfire is beneficial to the whole community, Hawks says, since it doesn't produce the heat and embers that can spread the fire to others.
"We're not going be able to keep fires out from every community under every situation, so we need to prepare communities and that's at the parcel level," Hawks says.
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