- 1Compartment wall, running from the floor slab to the underside of the slab above
- 2Compartment floor, separating one storey from the next
- 3Fire stopping, sealing pipes, cables and ducts where they pass through
- 4Cavity barrier, closing the hidden void above the ceiling
- 5Fire door, keeping an opening in the wall fire-resisting
Want to know if your compartmentation still works? Veritas surveys it, with destructive testing where needed. Fire Compartmentation Survey
What is fire compartmentation?
Compartmentation is the part of passive fire protection that limits how far a fire can spread inside a building. Each compartment is enclosed by construction that resists fire for a tested period. That buys time for people to escape, protects the escape routes and gives firefighters a contained fire to deal with. In blocks of flats it is what makes a Stay Put Policy possible.
What is fire compartmentation made of?
| Element | Role |
|---|---|
| Compartment walls | Fire-resisting walls running from floor slab to the underside of the slab above. |
| Compartment floors | Fire-resisting floors separating storeys. |
| Fire stopping | Seals around pipes, cables and ducts, and at joints, that restore the fire resistance of the wall or floor. See Fire Stopping. |
| Cavity barriers | Close hidden cavities so fire cannot bypass the compartment. See Cavity Barriers. |
| Fire doors | Keep openings in compartment walls fire-resisting. |
| Protected shafts | Stairs, lifts and risers enclosed in fire-resisting construction. |
What are the regulations for fire compartmentation?
For new and altered buildings, the Building Regulations require buildings to be subdivided into compartments where needed to limit internal fire spread; Approved Document B gives the guidance on where compartment walls and floors are needed and the fire resistance they must achieve. In blocks of flats, every flat is separated from the others and from the common parts by compartment walls and floors.
Once the building is in use, the Regulatory Reform (Fire Safety) Order 2005 requires the Responsible Person to keep these fire precautions maintained. A compartment that was built correctly but has since been breached by new services no longer meets that duty.
How long does compartmentation resist fire?
Compartment walls and floors are typically required to resist fire for between 30 and 120 minutes, depending on the building's use and height. Fire stopping and service penetrations should achieve the fire resistance of the wall or floor they pass through. Doors in compartment walls have their own required rating in Approved Document B, which is not always the same as the wall's.
How does compartmentation fail?
- New cables, pipes or data runs pushed through walls and floors without fire stopping
- Fire stopping with no fire test evidence for the service it seals, such as general-purpose expanding foam
- Compartment walls that stop at the ceiling line instead of continuing to the slab above
- Missing or broken cavity barriers in ceiling and floor voids
- Fire doors wedged open, damaged or missing seals
Many of these sit above ceilings and inside risers, out of sight day to day.
How is compartmentation checked?
A non-destructive fire risk assessment can only see what is exposed. Confirming compartmentation means opening ceiling voids and risers and, where needed, removing samples of fire stopping. That is a fire compartmentation survey. See also Fire Risk Assessment Types 1 to 4 for where destructive inspection fits.