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What fireproof material are you speaking about ? There are very little materials able to prevent a house from getting burned by wildfire. In my experience, unl

What fireproof material are you speaking about ? There are very little materials able to prevent a house from getting burned by wildfire. In my experience, unless you remove all the house opening and make the wall and roof out of concrete you are doomed because heat will find a way in and fire will take from the inside.

londons_explore 2y ago
For the LA fires, houses had to survive embers falling on their roofs for many hours, and intense radiant heat for only 10's of minutes. Tile roofs and brick walls survive both easily (standard european construction). Timber frame, plastic/wood on the outside, asphalt roof shingles, etc would obviously not survive. Which is why a few houses survived.
ben_w 2y ago
> unless you remove all the house opening and make the wall and roof out of concrete you are doomed I think you've answered your own question there. Concrete is cheap. My house is made from it. Also I have metal shutters on the outside of the windows. But also, from what I've seen, materials are not the primary cost of contstruction. If you took this plot of land, looks like 20 meters by 40 meters to me, the street view photo from before the fire looks like the building was 3 stories including the garage so let's say 10m tall: https://maps.app.goo.gl/XydopyQorcmgscPD8?g_st=com.google.maps.preview.copy https://maps.app.goo.gl/XydopyQorcmgscPD8?g_st=com.google.ma... 8000 cubic meters to fill the entire volume with solid concrete; I think concrete costs $80-$150 per cubic meter for a total of about $640k-$1.2M, while the pre-fire sale prices for that zip code were about $3.8M: https://www.realtor.com/realestateandhomes-search/90272/overview https://www.realtor.com/realestateandhomes-search/90272/over...
- aucisson_masque 2y ago
  Is your roof actually made of concrete ? It's very rare. Metal shutters is also uncommon, it's usually PVC. What country you live in ? Concrete is cheap but the steel used to reinforce it are not and concrete not reinforced is worth nothing so I don't know about your estimate.
  - ben_w 2y ago
    > What country you live in ? Germany. And there's rebar in the concrete of my house, yes. And my shutters are metal. Rebar adds to the cost, sure, but not as much as you think. Based on the high estimate of this price range, $4.41/sqft: https://estimatorflorida.com/cost-of-rebar-installation/ https://estimatorflorida.com/cost-of-rebar-installation/ … and having a property that fully encloses the entire previous example property boundary to a height of 10 meters, with full floor covering for 3 floors plus the roof all with rebar, that's only adding about $209k to the previous number: https://www.wolframalpha.com/input?i=%28%28800+*+4+%2B+%2810*%2840%2B20%2B40%2B20%29%29%29+square+meters%29+*+%244.41%2Fsqft https://www.wolframalpha.com/input?i=%28%28800+*+4+%2B+%2810... So, even with the largest possible structure fitting the same envelope, and the expensive end of the range for rebar, nowhere near the sale price of the property. Reducing this to the scale of the actual building that was there, nearly halves the cost of the rebar from 5% to 3% of the sale price, and the concrete (assuming 50cm thick walls and floors) in the range of 96-180k or 2.5-4.7% of the sale price. It's *everything else* besides materials that makes houses expensive. Given the low prices of adding reinforcement, the lesson from the Romans about getting by without reinforcement in concrete is more of an interesting side-note rather than a core point: https://en.wikipedia.org/wiki/Roman_concrete https://en.wikipedia.org/wiki/Roman_concrete

londons_explore 2y ago

For the LA fires, houses had to survive embers falling on their roofs for many hours, and intense radiant heat for only 10's of minutes. Tile roofs and brick walls survive both easily (standard european construction). Timber frame, plastic/wood on the outside, asphalt roof shingles, etc would obviously not survive. Which is why a few houses survived.

ben_w 2y ago

> unless you remove all the house opening and make the wall and roof out of concrete you are doomed I think you've answered your own question there. Concrete is cheap. My house is made from it. Also I have metal shutters on the outside of the windows. But also, from what I've seen, materials are not the primary cost of contstruction. If you took this plot of land, looks like 20 meters by 40 meters to me, the street view photo from before the fire looks like the building was 3 stories including the garage so let's say 10m tall: https://maps.app.goo.gl/XydopyQorcmgscPD8?g_st=com.google.maps.preview.copy https://maps.app.goo.gl/XydopyQorcmgscPD8?g_st=com.google.ma... 8000 cubic meters to fill the entire volume with solid concrete; I think concrete costs $80-$150 per cubic meter for a total of about $640k-$1.2M, while the pre-fire sale prices for that zip code were about $3.8M: https://www.realtor.com/realestateandhomes-search/90272/overview https://www.realtor.com/realestateandhomes-search/90272/over...

aucisson_masque 2y ago
Is your roof actually made of concrete ? It's very rare. Metal shutters is also uncommon, it's usually PVC. What country you live in ? Concrete is cheap but the steel used to reinforce it are not and concrete not reinforced is worth nothing so I don't know about your estimate.
- ben_w 2y ago
  > What country you live in ? Germany. And there's rebar in the concrete of my house, yes. And my shutters are metal. Rebar adds to the cost, sure, but not as much as you think. Based on the high estimate of this price range, $4.41/sqft: https://estimatorflorida.com/cost-of-rebar-installation/ https://estimatorflorida.com/cost-of-rebar-installation/ … and having a property that fully encloses the entire previous example property boundary to a height of 10 meters, with full floor covering for 3 floors plus the roof all with rebar, that's only adding about $209k to the previous number: https://www.wolframalpha.com/input?i=%28%28800+*+4+%2B+%2810*%2840%2B20%2B40%2B20%29%29%29+square+meters%29+*+%244.41%2Fsqft https://www.wolframalpha.com/input?i=%28%28800+*+4+%2B+%2810... So, even with the largest possible structure fitting the same envelope, and the expensive end of the range for rebar, nowhere near the sale price of the property. Reducing this to the scale of the actual building that was there, nearly halves the cost of the rebar from 5% to 3% of the sale price, and the concrete (assuming 50cm thick walls and floors) in the range of 96-180k or 2.5-4.7% of the sale price. It's *everything else* besides materials that makes houses expensive. Given the low prices of adding reinforcement, the lesson from the Romans about getting by without reinforcement in concrete is more of an interesting side-note rather than a core point: https://en.wikipedia.org/wiki/Roman_concrete https://en.wikipedia.org/wiki/Roman_concrete