[friend_Fernando]

Your argument only applies to unreinforced masonry, which is no longer allowed by code in seismically-prone areas. For fire resistance you can use reinforced concrete, steel or aluminum framing, or wood framing with non-combustible walls. Or even go exotic with various prefab options and 3D printing.

As for the higher cost, this has become mostly an urban myth. In regions with low construction costs such as the South or the Midwest ($130-180/sqft,) the cost difference is minimal. In areas with high construction costs such as CA ($200-700/sqft,) the difference is either immaterial or negative (thanks to the insurance savings.)

[jandrewrogers]

My argument applies to reinforced masonry as well. You seem to be operating from a naive model of what is required to prevent combustion of buildings. We already use non-flammable walls in a lot of places; it is a speed bump for a serious fire without a lot of additional mitigations.

Most typical reinforced masonry will fail during a severe earthquake, for which there is ample empirical evidence. The cost to reinforce masonry to e.g. a M8.5 standard is not small. The quantity of rebar, ties, etc required is expensive in both time and material. It isn’t cheap nor does the labor exist at the scale required.

I actually live in exotic construction, designed for extreme seismic and wind loads. Lots of steel, not much concrete, and extremely fire resistant (even though that isn’t a requirement here) but much cheaper to build and more seismic resistant (in theory) than reinforced concrete, which is what it replaces (its raison d’être). No structural wood either, but it wouldn’t be economical to construct a typical house this way.

This is an active area of research. If it was an “urban myth” there wouldn’t be so many engineering firms investing in developing new construction techniques that provide seismic resistance without the cost. If reinforced masonry actually worked in a reasonable way, we’d just use that.

[friend_Fernando]

I live in SF. The vast majority of new construction above 3 stories is reinforced concrete, including many high-rises such as the (infamous) 58-story Millenium Tower.[1] Seismically, modern reinforced concrete performs well.

As I explained in sibling threads, "speed bumps" are the most important thing here in CA. It's not about whether your structure can withstand a 1000-degree fire all around it. It's about whether your structure will set fire to three others within minutes of when it goes up in flames.

[1] https://en.wikipedia.org/wiki/Millennium_Tower_(San_Francisc...