Type 1, 2, 3 and 4 Fire Risk Assessments — What Each Type Actually Covers

The four types

The terminology comes from the LGA Fire Safety in Purpose-Built Blocks of Flats guidance, now embedded in PAS 79-2. The four "types" are defined by the scope of the assessment, not by methodology:

• Type 1 — Non-destructive common parts only
• Type 2 — Destructive common parts only
• Type 3 — Non-destructive common parts AND inside flats
• Type 4 — Destructive common parts AND inside flats

Type 1 — the default

Type 1 is the appropriate baseline for the majority of purpose-built blocks of flats. The assessment covers:

• Means of escape from common parts
• Common parts fire detection and alarm
• Fire doors visible from common parts (including flat entrance doors from the corridor side)
• Compartmentation visible in common parts
• Risers, plant rooms and bin stores

Nothing is opened up. Nothing inside flats is inspected.

Approximately 90% of UK blocks of flats are appropriately assessed at Type 1.

When to escalate to Type 2

Type 2 is appropriate where there is reason to suspect concealed defects in common-parts compartmentation. Triggers include:

• A previous Type 1 raised reasonable concerns
• Recent works in service voids or risers
• Buildings constructed during periods of known systemic defects (e.g. 1960s-70s LPS system-build)
• Insurer or lender demanding intrusive evidence

Type 2 typically samples 10-20% of common-parts compartmentation by opening service voids and risers.

When to consider Type 3

Type 3 looks inside flats but without intrusive work. Appropriate where:

• There is reason to suspect resident-led modifications affecting compartmentation
• Stay Put strategy is being reviewed
• Resident concerns or repeated fire incidents indicate flat-level risk

Type 3 typically samples 10-25% of flats by visual inspection only.

Type 4 — the most intrusive

Type 4 is the most intrusive assessment and the most expensive. It opens up samples of compartmentation both in common parts and inside flats.

Type 4 is appropriate where:

• Previous Type 1-3 has flagged systemic concerns
• The building is on the BSR HRB register and the Building Safety Case demands intrusive evidence
• Material change of use is planned
• Post-incident investigation

Type 4 should rarely be the first FRA on a building — it is usually the result of a stepped escalation.

Cost relationship

A rough relative cost ratio:

• Type 1 = 1x
• Type 2 = 2-3x
• Type 3 = 1.5-2x
• Type 4 = 5-10x

What your assessor should explain

A competent FRA proposal should explain:

• Which type is being delivered, and why
• Sample percentages for Type 2-4
• What will NOT be assessed
• The trigger that would warrant a higher type next time

MetroFire Type 1 through Type 4 fire risk assessments are delivered by NFRAR-registered assessors across London and the South East. Book yours.