Adjusting & Repairing Fire Doors

Fire doors are sturdy and, unless they are damaged, should have a lifespan of 20 years or more. They require a professional installation and need to be regularly inspected and maintained to ensure they can perform the life-saving job they’ve been designed to do.

Hardware such as hinges and door closers can wear over time, intumescent seals can become damaged as can the frame or the timber of the door itself. When this happens, the fire door or its components will need to be repaired or replaced.

When thinking about repairing or adjusting fire doors, you need to be careful. Any alteration or damage to the door or its surroundings can affect its performance.

All materials and products used in the installation or replacement of fire sets should be Certifire approved and where appropriate, CE marked.

Can a fire door be trimmed or cut to size?

When fitting a new fire door into an existing frame, it might need to be cut to size. Most fire door manufacturers allow some trimming allowance at the bottom of a modern fire door. Before you start to cut the door, speak to the manufacturer for accurate trimming information. The amount that is safe to trim can only be decided on a case-by-case basis.

Fire doors and frames may also deform over time which could also mean trimming is required. It’s always better, where you can, to buy a custom-made fire door to fit the frame precisely.

Fire Door Trimming Do’s and Don’ts

• Never trim the top of a fire door. The maximum amount which can be trimmed from the sides and bottom depends on the specific design of each fire door. The manufacturer verifies this for each door type by testing the complete fire door and frame.

• Frame to door gaps in a fire door need to be consistently 3-4mm. There should be no more than a 10mm gap at the bottom of the door. If the fire door must be smoke resistant as well, the gap at the bottom of the door should only be 3mm.

• Before trimming your fire door, remove it from its frame and check the edges. Remember that fire doors are solid timber and therefore very heavy, so take care when removing them.  

• If the door is a flush door and has wooden stiles (the vertical pieces around the edge of the door) of less than 40mm thickness it will weaken the door to trim these, so don’t. You need to make sure your timber-based fire door has a solid timber or chipboard core, solid throughout. The lipping must be at least 6mm thick after trimming.

• To cut the door, measure and mark where to trim. Use a straight edge as a guide and double-check all measurements before you begin. Plane the edge of the door to your mark. Only remove small bits of the door at a time so you don’t trim too much. Move from the end of the fire door into the middle using small strokes and then do the same from the other end.

• Don’t forget that a fire door must have an intumescent seal fitted around its edges. This expands if there’s a fire to seal the gaps between the door and frame. New doors and frames require an intumescent strip of 15mm wide. If it’s an existing frame, a 10mm wide strip is permitted.

Can I repair a fire door?

There are certain elements of a fire door that can be repaired. If you can replace seals, for example, without loss of integrity, there is no need to replace the entire door. However, if there are holes, missing parts or the door doesn’t fit in the frame, you must not fix the fire door, you’ll need to replace it.

Tips for Repairing Fire Doors:

• The door and frame need to remain square and should not be able to distort between the sides, top and frame. Minor surface damage can be repaired but if there are major defects in the door or the frame, you must replace them.

• If the intumescent seal is damaged or badly fitted, you’ll need to replace it. Smoke seals need to be replaced in one continuous length, if possible, to avoid leakage at the joints. Many manufacturers produce stick-on door strips either 10mm and 15mm wide to stick to the door or frame.

• You will need to replace the fire door hinges if there is visible wear or any dark marks around the knuckle of the hinge. Fire-rated hinges must comply with BS EN1935, so ensure you check when buying replacement hinges. All fire doors require a minimum of three hinges.

• Hardware such as locks, door knobs and latches with a locking mechanism must be CE marked. Mortice or tubular latches must comply with BS EN 12209.

• Fire doors need to shut automatically which requires an overhead door closer. If it is damaged or not working properly and needs replacing, fit Part M compliant closers certified to EN1154, EN1634 and Certifire approved CF388.

• With levers, check they fully return to the horizontal after use and that the latch engages smoothly and fully. If there are any problems, adjust, lubricate or replace.

• Don’t forget you must replace all fire-safe components like-for-like, according to the original specification.

• If the paintwork is chipped your fire doors can be painted. Check our detailed guide on painting fire doors for more detailed information. 

Fire doors save lives so it’s essential that they are correctly installed and maintained. When considering a fire door repair, ask yourself if you are sure that the work you are doing will comply with fire regulations. If in doubt, check with the manufacturer or speak to a professional installer. Don’t take the risk of an unsafe fire door.

Related Articles: How to adjust internal doors.