Compartmentation surveys

What a compartmentation survey is

Compartmentation is the division of a building into fire-resisting boxes so that a fire in one does not immediately become a fire in all of them. It is the assumption underneath almost every other fire safety measure in the building: the escape strategy, the stay-put policy in residential blocks, the time available to the fire service.

A compartmentation survey tests that assumption physically. It traces each compartment line on the drawing, then follows it through the building — above ceilings, through risers, into plant rooms and roof voids — and records every place the line is broken: unsealed service penetrations, incorrectly sealed ones, missing cavity barriers, walls that stop at the ceiling, damaged or removed fire stopping, and doors and dampers in the wrong place or the wrong condition.

It is not a fire risk assessment, and it does not replace one. A fire risk assessment considers the whole picture of risk; a compartmentation survey gives the assessor the physical evidence about the structure that a Type 1 assessment cannot obtain.

Intrusive or non-intrusive

A non-intrusive survey inspects what can be seen and reached without opening up: accessible ceiling tiles, risers with removable panels, plant rooms, roof voids with hatches. It is quicker and cheaper, and it will find a great deal — but it cannot tell you about a compartment line above a fixed plasterboard ceiling.

An intrusive survey includes agreed opening-up: access hatches formed, ceiling panels removed, sample openings made and made good. It is the only way to reach a defensible position in a building with sealed ceilings, and it is what a Type 4 fire risk assessment will normally require.

We price both and recommend a sampling strategy rather than blanket opening-up — a representative sample across construction types and floors, expanded where the sample shows systemic problems. That keeps the cost proportionate while still supporting a conclusion.

How we survey

We work from the fire strategy and compartmentation drawings where they exist. Where they do not — which is common in older buildings — we say so up front, because a survey without a defined compartment line is an inspection of holes rather than an assessment of compliance. In that case we can produce a measured compartmentation drawing as a first stage.

Every defect is photographed, classified by type and severity, and plotted at its actual location on the plan, not described as ‘riser, third floor’. Our surveyors record straight into Onetrace on a tablet, so the register exists the moment the survey ends rather than weeks later.

Each defect then carries the remediation required and a price against it, banded by risk so the client can see the difference between a breach in an escape-route compartment wall and a breach in a wall between two similar storerooms.

What we routinely find

• Service penetrations sealed with expanding foam, plasterboard offcuts or nothing at all.
• Fire stopping installed with the right product in the wrong detail — insufficient depth, wrong annular gap, no backing.
• Compartment walls stopping at ceiling level rather than continuing to the slab or roof.
• Cables added after the original seal, punched straight back through it.
• Missing cavity barriers at floor junctions and around the perimeter of curtain walling.
• Fire dampers absent, unlinked, painted over or immovable.
• Riser walls that have been opened for access and never reinstated.

Every defect plotted at its actual location — each pin opens the photographed record.

The deliverable, every time

From enquiry to certification

Answered by the people who do the work

More on the full FAQ page.

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