Brian G wrote:

It's the same with lintels and floor joists. In intense heat, a metal
lintel or joist will bend, warp and collapse quite quickly, whereas wooden
ones will burn on the outside but retain their strength for quite a long
period - and that's one of the reasons you will often see structural steel
surrounded with reinforced concrete.



ISTR one of the problems with the World Trade Center (sic) in 9/11 was
that the impact tore much of the fireproofing off the steel.

Andy