[brudgers]

Timbers burn more slowly than intuition might suggest because the fire first chars the flame exposed surfaces and the charred surfaces no longer contain much fuel to feed further combustion. The likelihood of charring rather than combustion is increased by chamferring the corners of the members.

The problem with incorporating steel into wooden buildings is the difference in coefficients of expansion. Not just thermal but expansion when exposed to bulk water or merely humidity as well. The reason reinforced concrete works is the similar thermal expansion of concrete and steel and their negligible expansion from moisture and humidity.

The development of better engineering methods to deal with wood's expansion in the past two decades or so is one of the reasons tall wood buildings meeting contemporary construction requirements have become more practical and widespread.