[randtrain34]

It actually doesn't, mass timber is extremely hard to ignite, see https://www.vox.com/energy-and-environment/2020/1/15/2105805... (advantages section)

[MichaelCollins]

5-over-1 buildings have been known to burn pretty well while under construction, when the building is bare timber with no fire suppression. But once the walls and sprinkler system go in, they resist fire well.

[jtlisi]

5/1 buildings in the US don’t usually use Mass Timber. They use traditional light framing techniques for the 5 wooden floors.