Look at the hinges before you look at the gap.
On most failed doors one of the three hinges has lost a screw or two, so the leaf sags on that side and the gap opens up at the latch. Put a screwdriver in each hole and you can usually find the loose ones in about a minute.
Hinges
A fire door normally hangs on three, and every screw hole should be filled with a screw of the right type. We find brass screws in steel hinges, and screws too short to bite into the frame. They get swapped for steel ones of the right length.
A worn knuckle is a different problem. Grab the handle and lift. A door that clunks has a hinge that is finished, and the new one has to be a fire door hinge, the same size as the old.
Paint over a hinge plate stops it sitting flat. It is often only a note on a report, but thick paint tends to sit alongside other neglect, so we clean the recess back and refit the hinge properly while we are there.
The gap
Around the top and both sides a fire door wants an even gap of about 3mm. The bottom can be larger, within what the door maker allows.
Even all round but too wide? A thicker lining strip fixes that. Wider at one corner than the other, with a scuff mark on the opposite edge? The frame has dropped and the door is catching.
Resetting a frame
That is the long job. We take the architrave off, free the frame, and pack it where it has dropped before fixing it back with proper frame fixings. Fire rated foam goes into the cavity, the architrave goes back on and we rehang the door and check all four edges.
Allow about half a day for each door. It is the main reason a quote that quietly assumes you only need hinges can turn out too cheap.
Planing
If a door scrapes, our carpenter can ease it with a plane. Only by a couple of millimetres though. Every maker publishes a limit and we stay inside it.
Questions we get asked
Can you measure the gap from a photo?
Roughly. Hold a ruler against the gap, take the picture square on, and send it with the others.
Do you take the door away to fit hinges?
Not usually. It comes off its pins for a short while and goes back on the same visit.
Send it with the postcode and we will come back with a fixed price per door.
Get a price