Fire Compartmentation Survey Costs in London: What to Expect

What a fire compartmentation survey checks

Compartmentation is the principle that a building is divided into fire-resisting compartments so that a fire is contained long enough for people to escape and the fire service to respond. A fire compartmentation survey checks that the dividing walls and floors achieve their intended fire resistance, that cavity barriers and fire-stopping are present where services pass through them, and that breaches — cables, pipes and ducts punched through a compartment wall and never sealed — are identified and recorded. It is a building-fabric assessment, distinct from a fire risk assessment, though the two inform each other.

Typical London cost ranges

As a broad market guide in London, a visual compartmentation survey of a single residential block or smaller building often falls in the region of around £1,500 to £4,000, while larger or multi-block estates, or surveys requiring extensive intrusive access above ceilings and into risers, commonly run well beyond that. The variable that moves the figure most is the proportion of intrusive opening-up: lifting ceiling tiles is quick, but cutting and making good access hatches in plasterboard, with the trades and reinstatement that implies, adds materially to the cost. These are market-typical illustrations only; we confirm a fixed fee once the building and the level of access are agreed.

Visual versus intrusive: the main cost driver

A purely visual survey reports what can be seen without breaking into the structure — valuable, but limited where the critical junctions sit behind finishes. An intrusive survey opens up a representative sample of those concealed zones to confirm the construction and the standard of fire-stopping. Most buildings need a proportionate mix: visual throughout, with intrusive sampling where the risk and uncertainty justify it. Agreeing that sampling strategy before anyone arrives on site is the single biggest control on cost, because unplanned opening-up mid-survey means a second mobilisation.

What pushes the cost up

The predictable multipliers are building height and the number of floors and compartments; the extent of intrusive access and the making good that follows; the number of blocks assessed together; difficult access to risers, voids and plant areas; occupied buildings needing out-of-hours or phased working; and the level of detail required by the end use — a survey feeding a remediation specification needs more rigour than a high-level appraisal. Fire door inspection is frequently scoped alongside, since doors are part of the same compartmentation line.

How it links to fire doors, the Building Safety Act and the FRA

Compartmentation rarely sits on its own. The fire doors that close off protected routes are part of the same line and are usually inspected together; passive fire protection more broadly covers the fire-stopping and barriers the survey examines; and for higher-risk buildings the findings feed the duties under the Building Safety Act and the building's fire risk assessment. Commissioning the survey with those downstream uses in mind avoids paying twice for overlapping access.

Getting value from the spend

Keep the cost proportionate by gathering existing drawings and any previous fire reports first, so the surveyor is not rediscovering the building from scratch; agreeing the intrusive sampling strategy up front; and sequencing access so opening-up, survey and making good happen in one coordinated visit. A clear, prioritised schedule of breaches — what is urgent, what is routine — is worth far more than a long undifferentiated defect list, because it lets you direct remediation budget where it matters.

Common questions

Is a compartmentation survey the same as a fire risk assessment? No. The FRA assesses overall fire risk and management; the compartmentation survey examines the fabric that contains a fire. A good FRA will often recommend one.

Do you need to open up every wall? No — a proportionate, representative sample is the norm, scaled to the building's risk and the certainty needed.

Why are quotes so different? Usually because one is visual-only and another includes intrusive access and making good. Compare quotes on a like-for-like scope before price.