I recently conducted a fire door assembly inspection and I noted that many of the existing frames had old holes that had been patched with Bondo filler putty. NFPA 80 requires that holes left by the removal of hardware must be filled with steel fasteners or with the same material as the door or frame. To the best of my knowledge, there isn’t a filler putty-type product that has been tested for this use. If anyone knows of a putty that is acceptable for use on fire-rated doors and frames, I’d love to hear about it.
Here’s the section from NFPA 80-2007 and 2010:
18.104.22.168 When holes are left in a door or frame due to changes or removal of hardware or plant-ons, the holes shall be repaired by the following methods:
(1) Install steel fasteners that completely fill the holes
(2) Fill the screw or bolt holes with the same material as the door or frame