Intumescent Strip & Smoke Seal Fitting in London

Intumescent Strip Fitting in London: The Signs You're Missing

Intumescent strip fitting in London isn't something anyone thinks about until a fire door starts sticking, or won't sit flush in the frame any more. So what's actually gone wrong here - the door leaf, or just the seal running round the edge of it?

Nine times out of ten it's the seal. In post-war council blocks across East London and South East London, the original timber doors are often decades old, and the strip inside the groove has gone brittle, crumbled away, or dropped out entirely. In Victorian and Edwardian conversions, we regularly find flat entrance doors that were never fire-rated to begin with - so there's no groove for a strip to sit in at all. And in newer composite doors fitted post-2000, the leaf's usually fine but someone's painted straight over the smoke seal during a redecoration, which stops it expanding the way it's supposed to in heat.

None of this shows up as an emergency. That's the problem. A door with a failed seal looks and closes almost normally right up until there's smoke moving through the building, and by then it's too late to matter. Buildings over 11 metres carry routine Regulation 10 checks, but those are visual walk-rounds, not a technical fix - when a strip's damaged or missing, someone competent needs to sort it properly. For the full picture on what we cover, see London fire door services. Left alone, it only gets worse.

What Intumescent Strip Fitting in London Actually Involves

Leave a failed intumescent strip alone for another six months and you're not saving money - you're just moving the cost further down the line, usually to a point where it lands as a full doorset replacement instead of a groove-out and re-fit. A strip that's split, painted over, or missing entirely doesn't fail quietly. It fails the moment someone with a clipboard opens that door, and by then it's not a quiet fix.

The job itself varies more than people expect. Sometimes it's straightforward intumescent strip replacement on a timber FD30 flat entrance door in a post-war council block, where the original seal has perished and the self-closer's been fighting a door that no longer seats properly. Sometimes it's a composite fire door on a post-2000 development in South East London where the leaf itself is fine but nobody fitted a smoke seal at all - compliant door, non-compliant gap protection, and that's exactly the kind of thing a proper fire door survey picks up that a quick look never will. And sometimes it's a steel door on a plant room in a commercial building where the strip's been overpainted so many times it's lost its ability to expand - the intumescent material is there, it's just sealed under three coats of gloss and useless.

Spec matters more than people assume. FD30 and FD60 doors call for different strip depths and expansion rates, and getting the wrong graphite-based intumescent material fitted into the groove is as good as fitting nothing - it just takes longer to be found out. We match strip size and rating to the door's actual test evidence, not a generic default, and that includes threshold drop seals where smoke control is specified, cold smoke seal continuity across the hinge side, and glazing bead intumescent tape where the leaf has vision panels. Letterbox kits and intumescent hinge pads get missed constantly on refurbished doors - small components, same consequence if they're absent.

Our installers are individually NAPFIS-accredited, with certification kept on file for completed works and remedial sign-off where applicable. Where hinges, closers or locks turn out worn or non-rated alongside the seals, that's fire door hardware installation territory - no point fitting a new seal to ironmongery that's already failing. Get the groove routed properly, the right profile fitted, and it stops being a recurring line item on every inspection report.