Intumescent Strip & Smoke Seal Fitting in Bow

Intumescent Strip Fitting Bow - When the Problem's Bigger Than It Looks

Intumescent strip fitting across Bow gets left longer than it should - and the longer it's left, the more it ends up costing. A door that's lost its seal doesn't announce itself. There's no obvious warning. It just sits there, looking like a door, doing less than half the job it's supposed to.

We see it constantly in this part of East London. Older council blocks where the seals around the door edge have either fallen out or been buried under decades of paint. Victorian terraced houses converted into flats along the streets off Roman Road - doors that were never properly fitted in the first place, gaps you could push your fingers through. Out towards Bromley-by-Bow in the newer developments, it's the opposite problem: doors that look pristine on the surface but are missing the cold smoke seal entirely, or fitted with the wrong profile for the door's rating.

And here's the thing - none of this is obvious until someone who knows what they're looking for actually checks. The gap might only be a few millimetres. The material around the frame might look intact. But if it's not the right product, correctly fitted, correctly sized for the gap, it's not doing what the regulations require.

That matters because a fire door without working seals isn't a fire door. It's just a door.

Leaving deteriorated seals on a fire door around Bow isn't just a compliance issue - it's a problem that compounds. A strip that's cracked, compressed flat, or buried under three coats of paint isn't doing anything useful. And the longer it stays that way, the more likely you're looking at a failed fire door inspection, pressure from a housing association or managing agent, and a remedial job that costs more than it would have done six months earlier.

The strip itself is straightforward enough in principle - a seal fitted into a groove around the door edge that expands under heat, closing the gap between door and frame before fire can push through. But the detail is where things go wrong. The correct strip profile, depth, and intumescent material all depend on the door's construction and its fire rating - an FD30 door in a post-war council block off Bow Road has different requirements to an FD60 door in a commercial premises on Roman Road. Fitting the wrong profile, or surface-mounting a strip where the groove's been painted over rather than re-routing it, isn't a repair - it's a liability.

We see painted-over strip replacement jobs regularly in converted Victorian terraces in this area. The strips have been there since the original build, painted over during every redecoration cycle until they're effectively sealed in place and useless. In those cases we rout the groove back out, select a compatible seal profile, and fit a combined intumescent and smoke seal strip - one product that handles both cold smoke and heat expansion in a single rebated section. That matters in a conversion where the flat entrance door is the primary means of smoke containment.

On the post-war council estates, it's often a different picture. The fire doors are original 1960s or 70s solid timber FD30 doors - sometimes still serviceable, often not - and the strips are either missing entirely or so degraded they've lost their integrity. If the door closer backcheck is also broken or non-compliant, which it frequently is, we deal with both in the same visit. No point resealing a door that won't stay closed.

Cold smoke seal fitting matters too, and it's still the component most often overlooked. The intumescent strip activates in heat - but cold smoke travels before the fire gets that far. A brush or blade smoke seal running alongside the intumescent seal is what restricts that passage. In residential blocks across Bow and into Bromley-by-Bow, we find corridor fire doors with no cold smoke seal at all, gaps well above the 3mm tolerance, and closers that barely pull the door shut. Any one of those is a problem. All three together means the door isn't functioning as a fire door in any meaningful sense.

Get the seals right and you've got a door that performs. Leave them as they are and you're not really protected - whatever the door looks like from the outside.

How Bow Intumescent Strip Fitting Actually Works

First thing we do is look at the door properly. Not just a glance at the strip - the whole door. Gap width, frame condition, what type of door it is, what rating it needs to achieve. You'd be surprised how often someone's had a strip fitted that's the wrong profile for the door. An FD30 door and an FD60 door have different specifications, and fitting the wrong strip doesn't just fail the inspection - it means the door won't perform if it actually needs to.

We see a lot of painted-over seals in Bow. Council blocks around here, some of them going back to the sixties and seventies, have had so many coats of paint applied over the years that the original intumescent strip is completely encased. It can't expand. It's just decoration at that point. Painted-over strip replacement is one of the most common remedial jobs we do - carefully removing the old material, checking the groove beneath is clean and undamaged, then fitting a correctly rated replacement.

Where a groove needs cutting - either because there's no existing rebate or the old one's damaged - we route it on-site. Properly. The depth and width have to be right for the strip profile, and the corners need clean mitres so there are no gaps in coverage. Hinge-side continuity matters here. A break in the seal at a hinge is a break in your fire protection, full stop.

Cold smoke seals go in alongside the intumescent material on most jobs. The intumescent strip deals with fire - but cold smoke travels before the heat builds, and that's what kills people in corridors. A combined intumescent and smoke seal strip handles both in a single install, which is often the tidiest solution. On some doors we fit them separately depending on the frame geometry and what the door's test evidence calls for.

For threshold protection we assess whether a threshold drop seal is needed - a lot of flat entrance doors in converted Victorian terraces around Bow have a gap at the bottom that nothing's ever been fitted to. That's a smoke leakage path that's been open since the conversion. It's not complicated to fix, but it does need the right seal profile selected for the floor type and the door's closing action.

Get it wrong and you're doing it twice.