If you have ever had to replace hardware from a fire-rated door with a new device, you know that the mounting holes on the new device do not always line up with the old ones. This means there will be holes left behind where the old hardware was attached, making the door incompliant with NFPA’s standards. Unfortunately, replacing a fire door can be costly, especially when there are only small holes located in the door. However, according to NFPA there are two methods to sealing up small holes caused by the removal of hardware.
NFPA 80, Section 126.96.36.199 (2010 edition): 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:
Install steel fasteners that adequately fill the holes
Fill the screw or bolt holes with the same material as the door or frame
But what about repairing the holes in a wooden fire door? Covering the holes with a section of solid wood or using wood plugs to fill in the holes is not acceptable. The door has to be Underwriter's Lab (UL) certified as a unit and any modification other than putting on or replacing firestop metal strips on the door will void that rating. Since the solid wood or wood plugs wouldn’t be fire-rated, they would burn quickly during a fire, allowing flames and smoke to pass through the barrier. So when repairing holes in a fire door, always contact the door and frame manufacturer to guarantee that your solution is acceptable.