When Do You Need a Compartmentation Survey? The Trigger List

The trigger list, expanded

• FRA recommendation: assessors hitting unverifiable construction ('ceiling voids not inspected — compartmentation survey recommended') — the escalation logic from the FRA types guide working as designed
• Stay-put dependency: purpose-built blocks' entire strategy rests on compartment integrity (the communal alarms guide's architecture) — periodic survey evidence is strategy maintenance, not paranoia
• Transaction moments: purchase/refinance due diligence — compartmentation defects are six-figure surprises better priced before completion (lender/insurer pressure increasingly forces it)
• Works archaeology: decades of M&E, IT and refurb trades with no penetration records (the universal condition) — surveys convert unknown to scheduled
• Building Safety Act safety cases: HRBs evidencing structural/fire integrity — survey outputs as case exhibits (the safety-case guide's evidence stack)
• Insurance requirements: underwriters of blocks/heritage/commercial increasingly name passive-fire evidence at renewal
• Incident behaviour: smoke where it shouldn't reach, multi-compartment spread — post-incident surveys reconstruct and remediate
• Change of use/occupancy: sleeping risk arriving (office-to-resi conversions) resets compartmentation expectations entirely

Type 2 vs Type 4 and survey depth

Survey depth calibrates like FRA typing (and overlaps it deliberately): visual/Type-2-style surveys (accessible voids, risers opened, sampling per risk) serve routine verification and most FRA-triggered commissions; intrusive/Type-4-style programmes (systematic opening-up, flat sampling in blocks) serve transaction depth, safety cases and defect-history buildings — the destructive-sampling economics coordinated once per the types guide's advice. Output standards define value either way: location-referenced defect schedules (floor plans, photographs, ratings assessed), prioritised remedial costings (the survey-to-programme chain the fire-stopping procurement guide completes), and evidence formatted for its audience (FRA reviewers, lenders, the Regulator — audience-aware reporting is half the product). Our compartmentation service runs both depths with the remedial loop closed in-house — survey, schedule, seal, register.

Costs and the do-nothing ledger

Survey investment: small-mid blocks/buildings £800–£2,500 visual-tier; intrusive programmes £2,000–£6,000+ by sampling scope; combined FRA-and-compartmentation commissions efficient per the coordination logic. The do-nothing side of the ledger, priced from our remedial files: stay-put strategies invalidated by survey-less drift (waking-watch money per that guide's brutal arithmetic), transaction renegotiations post-completion (the six-figure discovery pattern), enforcement following incident findings, and remedial programmes inflated by emergency procurement (planned sealing at £30–£120/penetration vs crisis rates). The rhythm recommendation: survey on triggers, then maintain via change-control (penetration permits for every subsequent trade — the golden-thread habit that stops the archaeology re-accumulating; our registers support exactly this). Buildings that know their compartmentation buy fire safety; buildings that don't, rent uncertainty.