The design team is interested in ventilating a small room by undercutting the door. The door is rated 90-minutes. Is it acceptable to undercut the door 1/2"-3/4" and maintain the fire-rating?
1. suggest you send an email to this person, and you will get a good answer::
I Dig Hardware » About Me
This is from 2007 NFPA 80
I Dig Hardware » Fire Door Clearance/Undercut
Looks like you can still do it, but would email the contact above::
I Dig Hardware » Decoded: Alterations to Fire Door Assemblies (December 2014)
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