Posted By Ashley Wood If you fill a fire door it would be void as far as an insurer was concerned. To satisfy BS476 Part 22 a fire door is tested as a complete component including specialist furniture. So once you have a hole in it it becomes void. Door handles should be suitable for the task and enable the handle on the side effected by fire to drop off, the handle link bar then melts and fills the gap. If an ordinary handle is used, the metal bar that joins the outer with the inner handle conducts heat and would fail. This is something I see a lot of where letter boxes have been cut in expensive fire doors used for flat entrance doors. Sorry, you will have to replace the doors.

Posted By Ghaam Before you go off changing all of your doos check with the Door and Hardware federation and manufactuers of Fire resistant sealants and fillers. Also discuss with your insurance company There may well be a suitable solution