What's Included in a Compartmentation Survey?

Compartmentation is one of the quieter parts of fire safety. It doesn't have the visible presence of a fire door or the annual paperwork of an alarm test, but it does one of the most important jobs in the building: it keeps fire and smoke contained long enough for people to get out and for the fire service to respond.

A compartmentation survey checks whether that containment is actually intact. Over the life of a building, walls get drilled for cabling, ceilings get opened up for maintenance, and partitions get moved during refurbishment. Each of those changes can breach a fire-resisting barrier without anyone noticing. The survey exists to find those breaches and tell you what needs fixing.

Here's what a thorough survey should cover.

What compartmentation actually means

A building is divided into compartments — areas separated by fire-resisting walls and floors designed to hold fire and smoke back for a set period, typically 30, 60, 90 or 120 minutes depending on the building's design and use.

For that to work, the barriers have to be complete. A wall rated for 60 minutes only performs for 60 minutes if there are no unsealed gaps, no unprotected service penetrations and no missing sections. A survey assesses whether the building's compartmentation matches what the fire strategy assumes it to be.

Establishing the compartment lines

Before anyone can assess whether a barrier is intact, they need to know where the barriers are supposed to be. A good survey starts by identifying the compartment lines from the building's fire strategy, drawings or fire risk assessment.

Where documentation is missing — which is common in older buildings — the surveyor will make a reasonable assessment based on construction, layout and escape routes. This part matters, because you can't judge whether a wall is doing its job if you don't know whether it's meant to be a compartment wall in the first place.

Inspecting walls and floors

The survey examines the fire-resisting walls and floors themselves, looking for:

• Service penetrations — cables, pipes, ducts and trunking passing through a barrier without adequate fire-stopping.
• Gaps and voids — openings at the head of walls, around structural steel, or where a partition doesn't fully seal against the floor slab above.
• Damaged or missing fire-stopping — sealant that has cracked, foam that has been cut away, or work that was never finished.
• Inappropriate materials — expanding foam or general-purpose filler used where a tested fire-stopping product is required.
• Unsealed builder's work openings — holes left after cabling or pipework was installed and never properly closed.

Checking above ceilings and below floors

The most common — and most overlooked — breaches sit in the concealed spaces: above suspended ceilings, in riser cupboards, and within floor voids. This is where services run, where trades work out of sight, and where fire-stopping is most often missed or disturbed.

A survey that doesn't lift ceiling tiles and open service risers isn't a compartmentation survey. Access to these areas is essential, and any areas that couldn't be reached should be clearly recorded as limitations rather than quietly ignored.

Fire dampers and ductwork penetrations

Where ductwork passes through a compartment wall or floor, a fire damper is usually needed to maintain the fire resistance of that barrier. The survey should note the presence — or absence — of dampers at compartment lines, though detailed damper testing is a separate exercise carried out to its own schedule.

Doors and other openings

Compartment walls often contain doors, and those doors have to hold the same fire resistance as the wall around them. The survey should flag doors on compartment lines that are missing, damaged, or clearly not fire-rated. As with dampers, a full fire door inspection is usually carried out separately, but obvious defects on a compartment boundary belong in the report.

What the report should give you

A survey is only as useful as the report it produces. A good one will include:

• The compartment lines identified, ideally marked up on plans.
• A record of each defect found, with its location and a photograph.
• A risk-based priority for each item, so you know what needs immediate attention and what can be scheduled.
• Clear remedial recommendations — what the fix is, not just that a fix is needed.
• Stated limitations, listing any areas that couldn't be accessed.

That last point is what turns a survey into an action plan. You should come away knowing exactly what's wrong, where it is, how serious it is, and what to do about it.

Why it matters for the responsible person

Under the Regulatory Reform (Fire Safety) Order 2005, the responsible person has to ensure fire safety measures are maintained in effective working order — and compartmentation is one of those measures. The Building Safety Act 2022 has sharpened the focus on how the safety of higher-risk buildings is demonstrated and recorded, particularly where the structural fire strategy relies on compartmentation performing as designed.

A compartmentation survey gives you the evidence that your building's fire-resisting barriers do what your fire strategy assumes they do. Without it, you're relying on the hope that no one has ever drilled through a fire wall — and in most buildings, someone has.

Next steps

If your building has never had a compartmentation survey, or if it's undergone refurbishment, cabling works or a change of use since the last one, it's worth arranging an assessment. The earlier a breach is found, the cheaper and simpler it usually is to put right — and the sooner you have the evidence to show your compartmentation is doing its job.