[bombcar]

People forget that you don't have to modify a McMansion to whatever requirements you're adding - you can build something entirely different.

"Earthships" or other hobbit-hole like houses are almost completely fireproof as long as the entries are handled correctly - anything that can start a fire through three feet of earth is probably a volcano anyway.

[Syonyk]

Don't most of those suffer from serious ongoing humidity problems? I've looked into that style of housing in the past, and it seems like it's always having issues with mold, mildew, and ohter "issues of running 90-100% interior humidity for long periods of time" sort of problems. I think they're okay in drier climates - IIRC they were developed in New Mexico, which is "bone dry nine months of the year, and somewhat drier the other three."

[bombcar]

They do - and there are ways to counteract it (the usual problem is similar to damp basements compounded by the lack of air movement and humidity control).

It’s a matter of cost (it’s almost never worth it) and tradeoffs.

But if fire survivability is paramount, it is an option.