Why compartmentation matters
Compartmentation divides a building into fire-resisting sections so that a fire is contained where it starts. In blocks of flats it's what allows residents in other flats to stay safe – and underpins a 'stay put' evacuation strategy. Over time, though, compartmentation is often breached: cables and pipes are added without fire stopping, ceiling tiles are removed, risers are opened up and cavity barriers are left out or damaged.
Most of these breaches are hidden, which is why fire risk assessments often recommend a dedicated compartmentation survey.
When you need one
- Your FRA recommends it – often because compartmentation can't be confirmed during a non-destructive assessment
- Before or after refurbishment or new services installations
- To support a fire strategy or retrospective strategy that relies on compartmentation
- For a safety case, where you need evidence that fire spread between flats and floors is controlled
- Before acquisition, as part of due diligence
What we survey
- Service risers and cupboards
- Above suspended ceilings in common parts
- Roof and loft voids, including separating walls
- Penetrations through compartment walls and floors – pipes, cables, ducts and dampers
- Cavity barriers where accessible
- Fire-stopping products and installation quality, including evidence of third-party certification where visible
What you get
A report with every breach photographed and located on marked-up plans, graded by priority, with recommended remedial solutions. This gives your contractor a clear scope and gives you the evidence to show the work has been completed when it is re-inspected.
What's included
- Review of fire strategy and compartment plans
- Survey of risers, voids and ceiling spaces
- Penetrations and fire stopping inspected
- Cavity barriers where accessible
- Every defect photographed
- Marked-up compartmentation plans
- Priority grading and remedial schedule
- Post-remedial re-inspection available
Compartmentation survey costs
Fees depend on the size of the building, how many areas need to be accessed (risers, ceiling voids, roof spaces, flats) and whether access equipment or out-of-hours working is needed. We'll fix the fee once we know the scope.
Where we work
Compartmentation surveys are carried out across London, Slough and Berkshire.
Guides on this topic
- Do I need a retrospective fire strategy?
- BS 9792:2025: what's changed for fire risk assessments in blocks of flats
- Fire door inspection requirements for blocks of flats (Regulation 10)
- Fire risk assessment types 1–4 explained (and when you need an intrusive one)
- Compartmentation surveys: when you need one and what they find
- Solar PV and battery storage fire risk: what to assess on your building
Related services
- Fire Risk Assessments – for flats, HMOs, offices and commercial premises
- Retrospective Fire Strategies – for existing buildings with a missing or outdated strategy
- Fire Door Inspections – quarterly and annual checks with remedial schedules