CompartmentationRebuilding the Fire Compartment LinesThat Protect Escape Routes
Reinstate compartment walls, floors, ceilings and risers to certified detail — surveyed against the fire strategy and rebuilt by a BM TRADA third-party certified specialist — so the building performs the way the fire engineer assumed it would.
5 years' passive fire experience. One accountable specialist for the whole compartment line.
What this service is — and when you need it.
Survey, repair and reinstatement of compartment walls, floors, ceilings, risers and service cupboards — sealing legacy breaches, unrecorded M&E routes and degraded construction back to certified detail.
HRB duty holders, housing associations, healthcare estates, managing agents and principal contractors delivering fire strategy remediation programmes.
Following an FRA compartmentation survey, during major refurbishment, after M&E works have breached the compartment line, or when a Type 4 fire risk assessment has opened up voids and exposed defects.
The fire strategy assumes the compartment line is continuous. In most existing buildings it isn't — legacy works, unrecorded penetrations and degraded blockwork mean fire and smoke bypass the escape route. Restoring the line is what makes the strategy real.
The consequence of leaving it.
- A broken compartment line means fire, smoke and hot gases move freely between flats, floors and escape routes.
- Stay-put strategies depend on compartmentation. A compromised line changes the evacuation strategy and the risk profile overnight.
- Duty-holder exposure under the Building Safety Act increases materially where the compartment line cannot be evidenced.
What we see go wrong.
- Treating fire stopping and compartmentation as the same trade — the sealant work is only one component of the compartment line.
- Not opening up ceiling voids and risers during survey — the worst defects are almost always out of sight.
- Rebuilding compartment walls in the wrong system for the required rating.
- Handing over without a drawing marked up showing which compartment lines have been reinstated.
A step-by-step system, from survey to handover.
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Step 1Compartmentation survey
Walk the compartment lines against the fire strategy drawings — walls, floors, ceilings, risers, cupboards and communal voids.
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Step 2Defect log and remediation strategy
Every breach classified by location, cause and required system. Priorities set against the FRA actions and the fire strategy.
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Step 3Reinstatement to certified detail
Walls repaired or extended in the correct system, penetrations sealed with tested detail, riser and cupboard integrity restored.
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Step 4M&E coordination
Coordinated with M&E first- and second-fix so new services don't re-breach the line the moment we leave site.
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Step 5Close-out pack per compartment line
Drawings marked up, photo evidence per line, systems and datasheets recorded for the building safety file.
Specific outcomes, not vague promises.
Compartment lines restored to the drawings the strategy is based on.
Evidenced compartmentation directly addresses the duty-holder's obligations.
Doors, stopping and compartmentation delivered by one team, not stitched together across three.
New services routed and sealed to keep the line continuous through and after installation.
Marked-up drawings and photo packs referenced to each compartment line.
Because the survey opens the voids — nothing significant is left to find later.
Materials, methods and where each applies.
The technical detail behind how compartmentation is scoped, specified and installed to certified detail.
Compartment walls, floors and ceilings
Reinstatement varies by system — blockwork, drylining on studwork, concrete slab, timber floor build-ups. Each has a tested detail for how the wall meets the slab, how a penetration is sealed, and how service voids are protected. Repair without matching the tested detail introduces failure at exactly the point the assessor looks first.
Riser and cupboard integrity
Risers are one of the most common compartmentation failure zones — service holes drilled at every floor, cable trays run without sealing, historic access hatches left uncertified. Restoring riser integrity means sealing every penetration and, where required, upgrading the enclosure itself.
Head-of-wall and construction joints
The point where a compartment wall meets the slab above is often incomplete — a strip of daylight above the blockwork, or a deflection head detail installed for structure but never sealed for fire. These are treated as linear gap work within the compartmentation package.
Coordination with M&E first- and second-fix
New services routed after our works are the fastest way to re-break the compartment line. We coordinate with M&E to plan penetration locations, back-boxing and sealing sequence, and to re-seal wherever second-fix has cut through.
What we do not offer
We do not offer a warranty on compartmentation works. The certified systems used carry their own third-party test evidence; our commitment is to reinstate strictly to those tested details and hand over a defensible evidence pack.
Straight answers on cost, timing and process.
How much does compartmentation remediation cost?+
Priced by programme, not day rate. Send the FRA or Type 4 survey and drawings — you'll get a scoped programme with evidence deliverables built in.
How long does compartmentation work take?+
Depends on floor count, access and how much void needs opening. Multi-floor HRB programmes are phased by floor over weeks to months; smaller works complete in days.
Do you guarantee the compartmentation works?+
No additional product warranty. The certified systems used carry their own test evidence; our deliverable is evidenced installation to those tested details.
How long should reinstated compartmentation last?+
Correctly reinstated and undisturbed, the compartment line performs for the life of the construction. The risk is later trades penetrating the line without sealing it — every future intervention needs the seal reinstated.
Do you carry out the survey as well as the works?+
Yes. Survey, remediation strategy and delivery come from one team, priced together, so nothing falls between roles.
Can you work in occupied residential blocks?+
Yes — most of the compartmentation work is in occupied HRBs, housing association stock and NHS estates. Access is phased and communicated to residents.
Do you deliver alongside our principal contractor?+
Yes, both direct to duty holders and as a subcontract specialist to principal contractors on major refurbishments.
Which areas do you cover?+
London, Kent, Sussex, Surrey and surrounding boroughs including Croydon, Sutton, Bromley, Sevenoaks and Crawley.
Can you close out an FRA on our behalf?+
Yes — the standard deliverable is a priced programme against each FRA action, closed out with evidence referenced to the action number.
Get a fixed quotation for compartmentation.
Send the FRA action list, drawings or a short scope description. You'll speak to Michael directly — not a call centre — and get a scoped, priced programme back.
Ready to scope your compartmentation works?
Send the FRA or a short brief. You'll get a priced, evidenced programme back — not a template quotation.