Doors, seals & hardware
Intumescent & Smoke Seal Replacement
Intumescent & Smoke Seal Replacement: Intumescent seals are strips set into the edge of a fire door or its frame that expand when heated to close the gap around the door. Smoke seals, usually brush or fin seals, block cold smoke before the intumescent reacts. Both are part of the door's tested performance.
Seals are the most common reason fire doors fail inspection: missing lengths, strips painted solid, brush seals flattened, or the wrong size fitted after a previous repair. Replacing them is quick and affordable, provided the new seals are the type and size the door was tested with.
What's included?
- Survey of the seal type, size and position for each door
- Intumescent-only or combined intumescent and smoke seals as required
- Seals on hanging, closing and head edges, and meeting stiles on pairs
- Old seals removed cleanly from the groove
- Threshold or drop-down seals where smoke control is required
- Gap readings checked so new seals can work
When do you need a fire door seal replacement?
- Seals are missing, broken or have been painted over
- Smoke control doors have flattened or damaged brush seals
- A report says seals are the wrong size or type
- Doors have been decorated and the seals were not protected
What do we check or do on each door?
| Type | Intumescent only or combined with a smoke seal, to suit the door's rating. |
|---|---|
| Size | Width and position match the door's evidence and gap. |
| Continuity | No breaks, overlaps or missing lengths. |
| Paint | Smoke seals free of paint so they can work. |
How does it work?
Identify
We confirm the seal type and size the door needs.
Remove
Old or damaged seals are removed and grooves cleaned.
Fit
New seals are fitted in continuous lengths, mitred at the head.
Check
The door is closed and checked for binding or gaps.
How much do fire door seal replacements cost?
Per door, depending on seal type and whether frames or leaves need grooves cleaning. Guide range £45–£110 per door, ex VAT. We confirm a fixed price once we know the building, door count and access. See all guide prices.
Which standards and law apply?
- BS 8214:2026
- BS EN 13501-2
- BS EN 1634-3 (smoke leakage)
Regulation 10 applies in England only. Wales, Scotland and Northern Ireland have their own fire safety law; see regulation 10 explained.
Intumescent & Smoke Seal Replacement: questions
Can intumescent strips be painted?
Brush and fin smoke seals should never be painted, because paint stops them working. Some intumescent strips tolerate a light coat, but the safest rule is to mask all seals before decorating and replace any that have been painted.
What is the difference between an intumescent strip and a smoke seal?
An intumescent strip expands in heat to seal the gap during a fire. A smoke seal, often a brush or blade, blocks cold smoke at lower temperatures. Smoke control doors, marked with an S such as FD30S, need both.
Can I just stick new seals over the old ones?
No. Seals should be fitted into the groove after the old seal is removed, in the size and type the door was tested with.
Will new seals fix a door with big gaps?
No. Seals only work within the gap they were tested with. Gaps outside tolerance need the door adjusting first.