“When we're inspecting healthcare buildings for fire door issues, any wood pair of double egress doors is almost guaranteed to fail."
- fire inspector
Any guess why wood doors would fail but not hollow metal?
Fire rated applications with wood doors are only allowed 1/8" clearance. Having a pair of wood doors be nice and plumb and square with only a 1/8" gap is pretty tough.
Fire rated hollow metal doors are allowed 1/8" clearance +/- 1/16". That extra 1/16" may not sound like much, but can be the difference between a passed inspection or spending a ton of money on remediation. Many distributors and architects prefer hollow metal for fire rated pairs for that reason.