Fire Compartmentation Explained: A Commercial Renovation Essential
In short
Fire compartmentation is the division of a building into sections enclosed by fire resisting walls, floors and doors, so a fire is contained where it starts for a set time. It protects escape routes and gives people time to leave. Every service that passes through a compartment must be properly fire stopped.
Fire compartmentation is one of the most important safety systems in any building, and one of the easiest to damage during a renovation. It works quietly: walls, floors, doors and ceilings are built to resist fire for a defined period, often 30, 60 or 120 minutes, so smoke and flames are held back while people escape and firefighters arrive.
Where compartmentation is found
- Between separate tenancies in a commercial building
- Between flats, and between flats and common parts
- Around stairs, lift shafts and risers
- Around plant rooms, kitchens and other higher risk areas
- Between floors in multi storey buildings
- Between a house and an integral garage, and around loft conversion escape routes in homes
How renovations break compartmentation
Most failures are small holes that nobody sees:
- New cables, pipes and ducts passed through fire walls and floors without fire stopping
- Fire doors replaced with standard doors, or fitted with the wrong hinges, seals or closers
- Ceiling tiles removed above partitions, opening up the void
- Recessed lights and downlights cut into fire rated ceilings without fire rated fittings
- Partitions built up to a suspended ceiling, rather than to the slab, where the design requires it
How it is maintained
- Fire stopping: tested sealants, collars, wraps, batts and pillows sized for each penetration and installed to the manufacturer’s tested details.
- Fire dampers: in ductwork passing through compartment walls.
- Fire doors: certified door sets with correct frames, seals, closers and signage.
- Cavity barriers: in ceiling and floor voids and external wall cavities.
- Records: photographs and logs of every penetration sealed, which are increasingly expected by building control and insurers.
Why it matters during refurbishment
A building is often most vulnerable while it is being worked on. Fire doors are propped open for deliveries, ceilings are open, and new holes are made every day. A well run refurbishment closes penetrations as it goes, keeps fire doors and alarms working in occupied areas, and checks compartment lines at each stage rather than leaving fire stopping as a final task.
The legal framework
New work must meet Part B of the Building Regulations (fire safety). For non domestic premises and the common parts of flats, the Regulatory Reform (Fire Safety) Order 2005 makes the responsible person accountable for maintaining fire safety, guided by a fire risk assessment. Since the Building Safety Act 2022, expectations around competence and record keeping have risen across the industry.
How we handle fire compartmentation at London’s Prestige
On commercial and multi occupancy projects, we survey existing compartmentation before work starts, coordinate trades so penetrations are planned, use tested fire stopping systems, and photograph each sealed penetration before ceilings close. You receive a clear record at handover for your fire risk assessment and building file. Read about related requirements in our entry on means of escape, see our commercial refurbishment service, and book a site visit to discuss your building.
Common questions
What is the difference between fire compartmentation and fire stopping?
Compartmentation is the overall system of fire resisting walls and floors. Fire stopping is the sealing of gaps and penetrations so that system keeps working.
Who is responsible for fire compartmentation in a commercial building?
The responsible person under the Regulatory Reform (Fire Safety) Order 2005, usually the employer, owner or managing agent, supported by a fire risk assessment.
Does fire compartmentation apply to homes?
Yes, in flats, between a house and an integral garage, and in loft conversions where the stair must be protected. Building regulations set the requirements.