Type 1–4 assessments & PAS 79
Fire risk assessment types 1–4 describe how far an assessment looks into a building’s structure — from a non-destructive review of the common parts (Type 1) to a destructive survey of common parts and flat interiors (Type 4). PAS 79 is the standard methodology assessors follow.
Last reviewed: June 2026
PAS 79 — the method
PAS 79 is the British Standards Institution specification that sets out the standard five-step methodology for fire risk assessment. PAS 79-1 covers commercial premises and PAS 79-2 covers residential. It is the approach insurers, regulators and competent assessors expect.
The four types
- ·Type 1 — non-destructive, common parts only (the most common for blocks of flats)
- ·Type 2 — destructive, common parts only (where construction needs verifying)
- ·Type 3 — non-destructive, common parts and a sample of dwellings
- ·Type 4 — destructive, common parts and dwellings (the most thorough)
Which type you need
Most non-sleeping commercial premises need a standard PAS 79-1 assessment. For residential blocks, a Type 1 is the usual starting point, with a higher type used where the risk or uncertainty about construction justifies it. The right level is a risk-based decision for a competent assessor.