All the lighter-weight joists made with OSB burn far faster than the 2x8s or whatever they replaced, and home furnishings are made with large amounts of flammable synthetics.
At a live-fire course I was on, the scenarios we worked on were fueled by stacks of wooden pallents, lit by an instructor's tiger torch. One of the instructors asked us if we knew the fuel equivalent of a typical love seat with synthetic foam, in pallets. We all figured it was lots, but not the real answer: NINETY.
https://www.nahb.org/-/media/NAHB/advocacy/docs/top-prioriti...
> As expected, the coefficient estimate for the percentage of houses built after 1989 (pctpost89) is negative and statistically significant. This implies that, in counties with newer housing stock, all else equal, the fire death rate is lower. Interestingly, when identical regressions to model 1 were run using different cutoff points for new stock, such as the percentage of houses built after 1979 or 1969 or 1959, the coefficients were of roughly similar size, were always negative, and the associated t-statistics were at least as significant.
The starting point of this though, was the idea that the materials in the house are actually better than in the past. To the extent that they'll tolerate fire longer before collapsing, they aren't, and the gases from the foam cushions, carpets and drapes are more toxic than ever. The reason this was drilled into our heads is that it means less time to get into a fire, and someone out, before we all have to leave for our own safety.
I am very surprised by this.
I'm sure that building codes ensure that the actual houses are more fire resistant. And fire fighting has probably come a long way.
But the typical home is full of processed plastic fabric. Which burns a whole heck of a lot faster than either cotton or wool. Carpet, curtains, clothes, furniture, etc.