A fire door often fails at the head or jambs because the clearance is past NFPA 80 -- about 1/8 inch on a hollow-metal opening (plus or minus 1/16 inch). That gap is a smoke and fire path. Replacing the door or frame is not the only repair.

GAP90 GapGuard kits keep the existing opening. A 16-gauge 9945 stop extender, NGP-Edge 9400 intumescent, and a 5050C fire-and-smoke bulb close gaps over 1/8 inch, up to 9/16 inch. Factory listing on GAP90 is up to 180 minutes on hollow metal and 90 minutes on wood. GAP90N is the same kit on a narrow soffit -- stops from 1/2 inch to 1-3/8 inch. Gray primer and charcoal are both here.

If the frame face is already cut or damaged, that is a patch or repair job (FP180 / FR180), not a stop extender. Smaller gaps that belong on the stop use self-adhesive 9200 (up to 60 minute) or 9750 (20 minute) intumescent. After a perimeter kit goes on, a 9275 ASA or 9225 T-strike shim may be required so the latchbolt still engages.