Homes Withstood the LA Fires. Architects Explain Why
74 comments
·January 14, 2025ramshanker
apocalyptic0n3
Wood is incredibly cheap here in the United States. Estimates I have seen in the past is a stone home will cost 15-25% more per square foot than a wood-framed home in the same location. Making it more resistant to earthquakes (a requirement in California) raises the price even further. At the end of the day, cost will almost always win.
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invalidname
We also build with concrete. In the USA wood is very cheap and it's easier to work with, so you end up with a larger house at half the price of a concrete house. Also wooden houses have a "warmth" that is missing from bricks.
The way Americans look at it is: I can get a house twice as big for less. I'll just get insurance with the money I save.
MisterTea
One thing I think about is concrete is a major consumer of energy and contributes a large amount of CO2, something like 8% of the global emission. Whereas wood literally grows on trees while sequestrating said carbon. I realize that there re efforts to make concrete carbon neutral but until that happens building with concrete is not environmentally friendly.
throw0101c
Greg Chasen, the architect interviewed, also mentioned in this Matt Risinger video, "Lessons From Two Surviving LA Fire Homes":
* https://www.youtube.com/watch?v=yZe-TlYxm9g
Some video sources in the description:
* "CAL FIRE / IBHS Demonstration Burn Timelapse": https://www.youtube.com/watch?v=AYvwogREEk4
* "Your Home Can Survive a Wildfire" (from NFPA): https://www.youtube.com/watch?v=vL_syp1ZScM
It's fairly well-known how to deal with wildfires:
* https://www.nfpa.org/education-and-research/wildfire/firewis...
We just have decades-old housing stock that can kind of be viewed as kindling. So new builds are probably better, but old ones can be renovated to improved methods. There are also things as a homeowner one can do to improve your odds (e.g., cleaning gutters, clearing dry brush, for vented attics have better screens).
criddell
The photo caption is:
> Along a stretch near Saddle Peak in the Santa Monica Mountains, some homes were destroyed while others were undamaged by the Palisades Fire.
The homes may not look damaged, but I bet they have a lot of smoke damage.
leeter
Sucker's bet. They almost certainly do. The question is more would the homeowners have actually been better off if the homes were more damaged requiring being rebuilt? Based on anecdotes from the Hawaii fires... the answer is: Maybe. Combustion products are notoriously hard to remediate. Just living in those houses post fire could be the equivalent of giving yourself smoke inhalation issues.
exhilaration
NY Times did a big article on this: http://bit.ly/3E9mA5U
Far fewer resources for those whose homes weren't destroyed but insurance should still cover the smoke damage remediation.
OptionOfT
They do. I worked with someone who was impacted by a previous fire in Thousand Oaks.
Both of her neighbor's houses burned down, but hers survived. Newer build / renovation / luck.
But regardless, they had to tear it down as the smell of the smoke was inside of the insulation and you can not get that out ever.
Edit: houses, not hoses.
butler14
Good time to run a fire resistant cladding company (or passivehaus design company) in the LA area -- I can only imagine, at least for those that can afford it, it's a no brainer if you're going to stay in the area
billconan
Why don't Americans build homes using concrete and bricks?
brudgers
Because historically, owning a house has been very affordable and lumber is abundant because the landscape was not denuded for firewood over the course of millennia.
Lumber is not timber. Lumber can be moved about by a single pair of hands and fastened with nails...American construction takes advantage of the industrial revolution and uses commodity nails.
Worth noting that where Americans use concrete and brick, they also use steel reinforcing so that their buildings don't collapse brittle collapse from earthquakes and wind.
pfdietz
Basically the entire eastern part of the US was denuded of trees, which have since grown back when uncompetitive farmland was abandoned.
Lumber is cheap because there's lots of land where we now farm fast growing trees.
Wood frame houses are cheap today because of the invention of the stamped metal framing connector, which has enabled large elements to be made off site in high volume. It's also why houses typically don't have attics anymore.
marky1991
"It's also why houses typically don't have attics anymore."
That's really strange to me, every house I've ever lived in (5 houses since 1991 , all in the southeast, all new construction) has had an attic and I can't even imagine what a house without an attic would look like. (I guess a flat roof, but only weird modern houses and apartments have flat roofs and there are not many modern houses)
twothamendment
"It's also why houses typically don't have attics anymore."
As someone who framed houses as a job and designed and built three of my own I disagree with your take on attics.
It is common for houses not to have an attic because builders must build cheap to compete. Attic space can be cheap square footage, but it has to be part of the plan from the beginning and is difficult to make it an option to pick.
You can indeed have an attic with "attic trusses". They are still built out of dimensional lumber and stamped connectors - the bottom chord will be much larger. I've seen them span 36', not sure what the limit is.
On one house, to do a partial attic was only $2000 extra for the trusses. Attics present other problems/expenses too, like additional stairs. (Many plans didn't have a place where extra stairs can be added as an option AND work with the truss layout.
HVAC is another issue. You either end up with a second system for the attic or need to have space in the floor below to run ducts to the attic space. Again, most of your cookie cutter plans didn't leave a space for this. When walking my HVAC guy through my house to plan ducts he asked how much of this closet he could have for ducts. I told him "as much as you need to make it work correctly". From the look on his face you'd think he won the lottery. He replied "no one ever says that!".
Attic spaces require different insulation techniques, they aren't difficult, but cookie cutters don't like different.
I've used attic trusses on 2 of 3 houses. The one where I didn't was because stairs, HVAC and I didn't need more space (full extra height basement, daylight windows - that was enough).
cogogo
Watching a typical multi family house go up down the street in Boston and the wooden framing is definitely still all nailed together. This is very typical in the US Northeast. No need for connectors when you have nails and nail guns. Where I see elements made off site it’s typically manufactured joists which would be far more expensive as single pieces of wood.
edflsafoiewq
Can you elaborate on why no attics?
jvanderbot
There are several factors already mentioned, but also b/c it's not really required, given all those factors. From TFA:
TIL about Class A wood. It is as fire resistant as concrete, apparently.
The biggest predictor about what burned: Age
> The architect says that he’s done hundreds of renovations in Southern California to make houses fire-resistant. Driving along a stretch of beach in Malibu this week, Dawson says that he counted five houses left standing; three were his projects. “I haven’t had any house burn that’s been brought up to the latest standard.”
> The orientation and exterior materials, including a metal roof and metal eaves, prevented a fire from sparking inside the roof, which is the way most homes burn down.
We know where fires come from, and under what conditions they spread rapidly in LA - because the santa ana winds blow generally the same direction. You can design neighborhoods and houses to survive that.
We also built right up into the hills, surrounding them with natural vegetation. Pretty, but basically a tinder box.
cbg0
> TIL about Class A wood. It is as fire resistant as concrete, apparently.
Being in the same category of a rating system does not mean it truly is as fire resistant as concrete. In Europe it would most likely not be classified as A1:
> An A1-Rated material is defined as a material that does not contribute to fire at any stage, including a fully developed fire.
The rating from the US is a bit more vague on the class A wood:
> Class A is the most desirable category for fire-rated plywood as it indicates a flame spread index of 25 or less.
"or less" isn't zero.
jvanderbot
A fair point - but several factors, focusing largely on roof design, were highlighted in the article. Taken as a whole, it makes the case that concrete is not a strict requirement.
That's all I'm trying to say.
l1tany11
Why do you think that would solve the problem?
Keep in mind stucco is very common in Southern California. Basically a 7/8” thick layer of concrete on all the exterior walls. It is fire resistant. Many such buildings burned down.
This isn’t the three little pigs where the brick house is the solution. And that wasn’t the moral of the story anyway.
SirHumphrey
The first house by the forest would probably still be destroyed, however the next one has a much better chance because it’s not next to a large flammable structure.
ajuc
Because old cities had these kinds of fires constantly (in my city there's still a paiting of a fire from 18th century that destroyed half the Old Town) and usually only stone/brick buildings survived.
This isn't a 0%/100% thing, but it increases the chances by a big margin.
throwup238
https://en.m.wikipedia.org/wiki/Earthquake
Concrete that can withstand M7-8 is a lot more expensive, mostly limited to commercial buildings. There’s plenty of brick homes in the rest of the country.
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spicyusername
This is such a worn out talking point.
Because concrete and bricks are more expensive and for most places wood construction is perfectly adequate.
It's really very intuitive.
HPsquared
How much more expensive compared to the fire risk? This is where risk pricing is important.
apocalyptic0n3
From the article:
> Some of the homes in Pacific Palisades were 90 years old
90 years exceeds your lifespan, the lifespan of your children, and maybe the lifespan of your grandchildren depending on when in your lifetime it is built. Even if the house is never sold and is simply inherited, it is very likely that a home that age is lived in by someone the builders never met.
So if a house burns down once every 3 generations, what incentive is there to build it to be more fire-resistant? These fires are bad, yes. But LA isn't burning down once a year. LA is massive and only small chunks are affected by each fire. For reference, these fires are the most destructive in history and have destroyed an estimated 12,000+ structures throughout metro LA and Riverside. Per ChatGPT, there's an estimated 3 million buildings in LA County alone with the rest of the greater metro area (San Bernadino, Orange, Riverside, and Ventura counties) have an estimated 5 million.
So while, yes, the odds of your home burning down are elevated in metro LA, they are still quite slim. Slim enough that making the initial building even more expensive is not worth it, especially not in an area that also sees a lot of earthquakes.
infecto
And this is where insurance when allowed to set premiums, can help guide the market to the right solution. I don't believe LA has ever had a fire of this scale. Similar to that large fire in NorCal a few years back.
I am certain either through insurance requirements or simple price comparisons, homes that are getting rebuilt will be done so using modern standards. Its worth mentioning that a lot of this is not so much a concrete vs wood discussion. You can absolutely build a wood framed home that is fire resistant.
elzbardico
Americans are incredibly resistent to change and due to exceptionalism they have this idea that whatever they do is better than what anybody else. That's the real reason.
infecto
Its historically cheap, unlike Europe. More importantly I thought think it buys you much compared to building up to modern standards. Remember most of these homes are old. I think this is one of those European/World memes that America just builds cardboard homes.
UniverseHacker
Unreinforced masonry is illegal in most of California- it essentially fractures into a swarm of heavy projectiles during an earthquake- which is a bigger risk than fires here. Brick homes are very common on the east coast where they don’t have frequent earthquakes.
Commercial style construction with steel beams and reinforced concrete is extremely expensive, and not very warm/classic looking. It is used in a tiny fraction of extremely high end custom homes for wealthy people that like modern and brutalist style homes.
elzbardico
One important clarification for americans: Most of European, Middle Eastern and Latin American houses are not fully built on concrete.
Reinforced concrete is used most of time only for the structure.
The walls themselve are masonry.
LinuxBender
Archive [1]
[1] - https://archive.is/AVDKU
oldpersonintx
[dead]
I am a civil-structural engineering and have obvious bias for Concrete. Over here in India, literally all houses are built using Concrete and Burnt-Clay-Brick / Fly-Ash-Brick Masonry. I hope Concrete gets promoted more as a building material. They buildings which are professionally designed easily withstand 2500 Year Return Period magnitude earthquakes. Last time I enquired on HN about preference for Wood in US (remote areas) Building Materials, someone said, can't design house venerable to High Seismic Activity. While my exposure to US Building codes is limited, I know for sure, ASCE (American Society of Civil Engineers) have excellent Earthquake Loading criteria. It should be doable. Perhaps some regulation could help there.
A personal example: Wardrobes are usually made using synthetic-wood over here in India. I went a step ahead, and got it build using Steel-Sheets. So a major chunk of fire potential removed from the house. And it was within 10% of the cost of wood work. Termite free forever as bonus ! Have a look at the photos in google maps listing of the local manufacturer. https://maps.app.goo.gl/7Wrt4rNtcpez53Bm6