alt.hn

1/14/2025 at 12:20:32 PM

Homes Withstood the LA Fires. Architects Explain Why

 https://www.bloomberg.com/news/articles/2025-01-13/los-angeles-wildfires-why-these-homes-didn-t-burn

by JumpCrisscross

1/17/2025 at 2:11:42 PM

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

by ramshanker

1/17/2025 at 2:37:32 PM

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.

by apocalyptic0n3

1/17/2025 at 9:33:41 PM

In Europe, usually the cost of land is considerably higher than the construction. Must be true in rich parts of LA too.

by rich_sasha

1/17/2025 at 2:23:40 PM

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.

by invalidname

1/17/2025 at 3:06:25 PM

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.

by MisterTea

1/17/2025 at 6:27:50 PM

Adding to that, concrete buildings rely on a lot of steel, which is another major emissions driver, and production of both also leave a lot of toxic waste behind.

Construction should try to use both sustainable materials wherever feasible, and strongly favour refurnishing existing houses over new buildings.

by 9dev

1/17/2025 at 8:00:47 PM

But if you live in a tinderbox like California, that will only get worse from climate change, how long will that sequestration actually last? How much carbon will be emitted rebuilding and replacing?

by readthenotes1

1/17/2025 at 2:18:13 PM

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).

by throw0101c

1/17/2025 at 1:22:03 PM

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

by butler14

1/14/2025 at 12:31:15 PM

Why don't Americans build homes using concrete and bricks?

by billconan

1/14/2025 at 8:21:23 PM

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.

by brudgers

1/17/2025 at 1:01:11 PM

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.

by pfdietz

1/17/2025 at 1:25:33 PM

"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)

by marky1991

1/17/2025 at 4:18:29 PM

“Attic” has several usages. Traditionally it is a habitable story between the eaves and roof. An analog to a basement.

In a lot of contemporary construction it is an uninhabitable space between the eaves and roof. An analog to a crawl space.

In contemporary construction, habitable attics usually get listed as bonus rooms.

The GP is thinking of something reached by stairs. Nonhabitable attics usually are accessed by ladders or ladder like objects.

by brudgers

1/17/2025 at 1:34:04 PM

Additionally every single new construction I've seen in greater Boston metro area in the past 20 years has not brought in any pre-assembled elements from outside. Just piles of various sizes of lumber and assemble on-site.

(Edit: to be clear this is for residential construction which tend to be small 1-2 story buildings.)

by foobarian

1/17/2025 at 4:29:24 PM

Here's an example of a Boston area builder doing just that.

https://www.youtube.com/watch?v=2f4nqf_HgnY

by pfdietz

1/17/2025 at 7:05:51 PM

Sure but I don't buy it's being done at scale. Even in that video they are mentioning an unusual design as a partial reason for the pre-fabbed elements.

by foobarian

1/17/2025 at 2:05:49 PM

Attics have been replaced by engineered trusses to hold up roofs. The trusses are made of.... wood. These trusses are also made offsite. This leaves very little room for usable attic space.

by wbshaw

1/17/2025 at 4:23:00 PM

When designed for minimal load on the bottom chord, plate connected wood trusses cost significantly less. Not just for materials, but less to install because they weigh less.

by brudgers

1/17/2025 at 2:29:06 PM

"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).

by twothamendment

1/17/2025 at 1:37:00 PM

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.

by cogogo

1/17/2025 at 1:44:16 PM

I believe the post you're replying to is referring to roof trusses (and perhaps floor trusses) which are generally built off-site at a truss plant, but then attached onsite (usually with nails, but sometimes lag bolts or screws are needed).

by bkjelden

1/17/2025 at 2:06:52 PM

It's not nails that make metal framing connectors not required, it's that modern platform framing doesn't typically need much of them due to design, except for trusses (mending plates) and rafters (metal ties). Nails are used to secure the framing but aren't generally used to provide a structural connection.

by rascul

1/17/2025 at 1:28:02 PM

Can you elaborate on why no attics?

by edflsafoiewq

1/17/2025 at 1:34:53 PM

The stamped metal framing connector facilitated the use of trusses, which means an open plan house (McMansion) of much larger footprint. Trusses mean no attic.

https://www.youtube.com/watch?v=3oIeLGkSCMA

Ninja'ed

by sgtaylor5

1/17/2025 at 1:46:31 PM

You can absolutely design trusses to have an attic. They're called "room in attic trusses".

I would guess the decline in livable attics in new construction is mostly attributable to changing consumer preference.

by bkjelden

1/17/2025 at 2:01:04 PM

At least where I am, I would attribute it to code requirements. A livable attic requires much more work to meet code than a vented attic space. Not to mention the energy cost of having a livable attic can be higher because there is no venting and limited insulation. All of this is speculation of course. You definitely could do it. But, if you did you'd almost certainly have to use more expensive construction techniques to meet code insulation requirements.

by leeter

1/17/2025 at 5:40:59 PM

On top of that, a usable attic is a third story. Once you go 3 stories, you need a fire sprinkler system installed.

by derekp7

1/17/2025 at 1:39:07 PM

There's still an attic with many typical roof truss designs.

by rascul

1/17/2025 at 1:57:29 PM

I think a lot of people in this thread are too young to understand what is meant by attic. Go upstairs in a house built in 1920, that’s an attic. A tiny cubby in a cavity left by engineered trusses is not. You’ll also notice the modern house, even a cheap one, is far better insulated.

by LastTrain

1/17/2025 at 2:10:08 PM

> A tiny cubby in a cavity left by engineered trusses is not.

Yes, it is. It doesn't have to be usable to be an attic. It just needs to be a space between the ceiling and roof.

by rascul

1/17/2025 at 2:26:31 PM

Yes it fits the definition of the word, but not the context in which it was brought up here.

by LastTrain

1/17/2025 at 2:45:25 PM

I realize now perhaps they meant livable attic. That wasn't obvious to me. Crawling through non livable attics framed with trusses is part of my work sometimes.

by rascul

1/17/2025 at 3:17:09 PM

It is what I meant, but the confusion from the ambiguity is completely understandable.

by pfdietz

1/17/2025 at 1:01:04 PM

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.

by jvanderbot

1/17/2025 at 1:41:05 PM

> 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.

by cbg0

1/17/2025 at 2:17:36 PM

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.

by jvanderbot

1/14/2025 at 11:20:42 PM

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.

by l1tany11

1/17/2025 at 1:50:13 PM

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.

by SirHumphrey

1/17/2025 at 1:35:54 PM

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.

by ajuc

1/17/2025 at 1:08:29 PM

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.

by throwup238

1/17/2025 at 12:51:14 PM

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.

by spicyusername

1/17/2025 at 1:20:28 PM

How much more expensive compared to the fire risk? This is where risk pricing is important.

by HPsquared

1/17/2025 at 1:37:16 PM

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.

by infecto

1/17/2025 at 2:31:31 PM

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.

by apocalyptic0n3

1/17/2025 at 3:46:46 PM

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.

by elzbardico

1/17/2025 at 1:09:58 PM

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.

by infecto

1/17/2025 at 12:57:09 PM

Aside from what others have mentioned - maintenance/upgradability. I own a home in Costa Rica, which is basically all concrete. Try upgrading your building with Cat6 ethernet when you have concrete (vs wood/sheetrock).

by mbesto

1/17/2025 at 12:59:22 PM

European here - it's easy, the solution is called conduit

by lousken

1/17/2025 at 1:09:04 PM

Bosch also sells those huge ass drills here that take a few minutes to make a 2-3 cm hole through concrete to pass those conduits between floors/rooms. They're not available in the Americas?

by nottorp

1/17/2025 at 1:29:51 PM

Patching sheetrock is 10x easier than concrete and looks way nicer. Protruding conduit does not look good.

by mbesto

1/17/2025 at 1:32:20 PM

Isn't the conduit inside the ... whatever ... plaster? ... you put over the hard concrete wall, I don't know the name in english?

It's definitely not protruding in my home... and it's all conduit in the walls.

by nottorp

1/17/2025 at 2:31:39 PM

Drywall is common in north america. It's ~1.25m×2.5m×1cm sheets of gypsum sandwiched between a heavy paper, and plaster is only used to bridge the seams. It's almost always screwed down, and adds significant rigidity to a stick-framed wall. Cement walls are often (but not always) finished by stick-framing a false wall and then screwing the drywall to that.

by cwillu

1/17/2025 at 2:40:30 PM

I've built three houses in the USA. I don't use conduit everywhere, but have always installed some in places where I think I might want something in the future. I've never regretted it.

Most useful was from my attic (not livable space) up in the trusses to my basement utility room. When I convinced a local WISP to use my roof for a back haul and access for the neighborhood it saved them (and me) from running wires all over the outside of my house and was a quick, clean install.

Conduit is common in commercial work here, but almost never in residential.

by twothamendment

1/17/2025 at 1:30:20 PM

Hiti Diamond Drill

by inemesitaffia

1/17/2025 at 1:56:34 PM

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.

by elzbardico

1/17/2025 at 2:03:31 PM

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.

by UniverseHacker

1/17/2025 at 1:29:45 PM

In earthquake prone areas concrete and bricks fall over. You want that in hurricane prone areas.

by Over2Chars

1/17/2025 at 3:43:47 PM

Not reinforced concrete built to code.

Contrary to common American percepctions, there are other places in the world with Earthquakes.

by elzbardico

1/18/2025 at 1:44:36 AM

I like how despite my comment on Japan, I'm characterized as a geographically challenged American.

How about you take your stereotypes and go have a nice burger at McDonald's?

by Over2Chars

1/17/2025 at 1:15:49 PM

Specific to LA, earthquakes

by JOnAgain

1/17/2025 at 1:19:55 PM

Among the reasons listed here, producing concrete also emits a huge amount of CO2 while lumber in houses are effectively carbon sequestration.

by x3n0ph3n3

1/17/2025 at 1:31:43 PM

Not if it burns down

by WithinReason

1/17/2025 at 1:37:39 PM

Yes, all homes in America burn down every 5 years.

by infecto

1/17/2025 at 1:33:24 PM

They do, I grew up in a brick house, both my grandparents lived in brick houses...

by astura

1/17/2025 at 1:40:06 PM

It is probably a house with a brick veneer, not a thick, load-bearing brick house.

by megaman821

1/17/2025 at 3:44:35 PM

Yes, unless it is 100 years old, the framing is either reinforced concrete or steel beans(less common)

by elzbardico

1/17/2025 at 6:26:47 PM

All the houses I'm talking about are older than 100 years.

by astura

1/17/2025 at 1:25:00 PM

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.

by criddell

1/17/2025 at 1:45:45 PM

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.

by leeter

1/17/2025 at 1:58:12 PM

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.

by exhilaration

1/17/2025 at 4:27:30 PM

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.

by OptionOfT

1/17/2025 at 1:40:23 PM

[dead]

by oldpersonintx