Why some structures may have withstood the Los Angeles area wildfires – while those next door burned to the ground

By Dakin Andone, CNN

(CNN) — Sitting in the hotel room where his family sheltered from the Eaton Fire, Eric Martin was certain his Altadena, California, house – the place he’d once believed his 1- and 3-year-old sons would know as their childhood home – was gone.

When a friend sent him a photo of the house still standing, he and his wife held each other, stunned, crying discreetly to not alarm their boys.

“I couldn’t believe it,” Martin told CNN on Monday, his voice breaking. “The fire was moving so fast. I thought for sure it was going to be gone. It just did not even seem possible that it could still be standing, and there it was.”

Martin returned to the house later that day to find it was indeed still there, as were those on either side of it. Almost everything else is on his block gone.

“It’s just ash and naked chimney spires,” he said.

As many as 12,000 homes, businesses and other structures may have been destroyed in the wildfires raging in Los Angeles County, rendering entire communities ashen piles of rubble.

But here and there amid the Palisades and Eaton fires, in places not protected by the private fire crews of the wealthy, a home survived – an apparent miracle – raising questions about how one structure can make it through while others within shouting distance burn to the ground.

While it may be impossible ever to know for sure, several variables could be in play for those homes that survive, experts say: a smart, fire-resilient design; an owners’ preparation, like clearing away flammable vegetation; the sometimes-unknown intervention of firefighters; the wind and weather; or, frankly, luck.

“You’ve seen some examples where ‘luck’ isn’t the worst word to describe how some homes survived,” said Janice Coen, a project scientist at the National Center for Atmospheric Research who studies fire behavior.

“But sometimes people just don’t recognize the factors in the physical environment,” she said. “It might be luck, it might be some action they took.”

Design, construction and preparation

It might seem a home’s survival depends heavily on its construction. And indeed, the California Department of Forestry and Fire Protection is increasingly encouraging homeowners to “harden” their homes, implementing features to help fireproof them.

This can include building or retrofitting key parts of a home – like roof, walls, windows, decks, garages, fences and gutters, among others – with more ember- and flame-resistant materials, like concrete and steel.

Architect Greg Chasen believes a number of these features helped save a home he designed and helped build just last year that survived the Palisades Fire: He posted on X a photo of the home, showing it almost untouched, standing pristinely next door to its neighbor, now a charred husk with a burned-out vehicle sitting on its frame in the driveway.

Building the home to withstand a wildfire was not a “priority in the design,” Chasen told CNN. But he and the owner had both witnessed firsthand these kinds of fires, and they proceeded with that threat in mind. “Once you see what a wind-driven fire can do, I don’t know – it’s just indelible.”

The architect pointed to features including the home’s walls: fire-rated for one hour, meaning a fire could be adjacent to the wall for that length of time without igniting. The roof was made of non-combustible materials, he said, as was the deck’s finish.

The tempered, multi-pane glass windows were also a “huge part of the equation,” Chasen said. The sole damage to the home was to two of the exterior panes – one cracked, while the other below it shattered entirely. But the interior panes held, Chasen said, preventing sparks from entering the home, where the furniture could have fueled the fire.

In California, adding wildfire safety measures beyond building codes can boost new home construction costs by 2% to 13%, according to a report from the Insurance Institute for Business and Home Safety. Reinforcing existing homes can vary and likely ranges from $2,000 to $15,000, while full hardening could cost as much as $100,000, according to Headwaters Economics, an independent, nonprofit research group.

Chasen also credited the owner for taking steps to prepare the home. Its landscaping was already spare, the architect said, but as the fire approached, the owner spent hours cleaning the grounds. For instance, he propped open a wooden gate attached to the house, which could have acted as a “fuse” if the fence caught fire, Chasen said. Trash and an outdoor barbecue were also kept away from the home.

This is called creating a “defensible space” around the home, said Coen: a buffer zone cleared of flammable materials, like the dry vegetation that has helped exacerbate this round of Southern California’s fires. Creating this “defensible space,” she said, gives a home a higher probability of survival by reducing sources of “radiant heat” directly on a home.

“We tend to think of big fires ripping through the trees,” she said. “But it can often be little fires creeping up to the home, and that’s why the defensible space is so important.”

The influence of wind – and sheer luck

Firefighters look for these elements, Coen noted. And they make decisions about which homes might be more defensible than others and thus worthy of the resources necessary to save them.

“Our experiences, as firefighters on the ground, we see which homes are able to be saved and which ones are destroyed,” State Fire Marshal Daniel Berlant told CNN in November, as a different wildfire scorched nearly 20,000 acres outside Los Angeles. “The research we have done really has led us to be science-based in the ability to say that if you do these mitigations, you are significantly more likely to have your home survive a wildfire.”

But there’s often no evidence of whether a first responder worked to defend a home, said Alexander Maranghides, the senior technical lead of the wildland urban interface group for the National Institute of Standards and Technology, part of the US Commerce Department.

Indeed, nailing down why a home survived can take an in-depth, yearslong investigation and reconstruction of the type Maranghides’ team conducts, he said, pushing back on the idea of a “miracle home.”

“It’s not a miracle, it’s just we don’t know,” he said. “Was it luck? Was it the wind? Was it the wind and the defensive action? What happened? You cannot say because you don’t know.”

Some homes – not including those protected by pricey private fire crews that often spark backlash – survive because a firefighter happened to be well-placed to defend them.

Another factor could be the wind’s direction, which can vary rapidly in both space and time depending on the weather, topography and air temperature, among other variables, said Coen, who works to determine how a fire may spread based on air flow, weather and the winds the fire creates.

“Even in the wildlands, away from homes, you’ll see what we call the ‘burn mosaic.’ That is, there will be a lot of variability in the severity of the combustion,” she said. “Some areas will be burned completely, but other areas nearby will be untouched, and you’ll have islands of unburned fuel.”

In an urban environment, “why one (house) survives might be some really local wind effects that you might not be aware of,” Coen said.

As for Martin, whose Altadena home survived, he has no idea why his house is still standing. It’s a stucco home – among those fire-resistant materials. But it’s also surrounded by dry vegetation and brush that hasn’t seen rain in months.

“It just seems,” Martin said, “like pure, dumb luck.”

CNN’s Alaa Elassar contributed to this report.

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