Type 1, 2, 3 and 4 fire risk assessments — explained simply
Matt McAllen, CMIOSH
Last reviewed: June 2026 The four "types" apply to blocks of flats and shared housing, and they describe how far the assessment looks. Type 1 covers the common parts only and is non-destructive — it's what most buildings need. Types 2 and 4 are destructive (opening up the structure); Type 3 adds a sample of the flats. I carry out Type 1 and Type 3, and refer out the intrusive Type 2 and Type 4 work.
What are the four types of fire risk assessment?
They're a way of describing the scope of a fire risk assessment in residential buildings — how much of the building the assessor looks at, and whether they open anything up. The framework comes from the housing fire-risk-assessment standard (now BS 9792:2025, which replaced the older PAS 79-2). It applies to blocks of flats and shared housing such as HMOs — not to ordinary single-occupancy commercial premises, which are assessed to PAS 79-1.
The four types split along two simple lines: how much is assessed (just the shared/common parts, or the individual flats and rooms too), and how deeply (non-destructive — what can be seen and reasonably inferred — or destructive, where parts of the structure are opened up to inspect concealed fire protection).
Type 1 — common parts, non-destructive
The shared areas only — hallways, stairs, landings and escape routes — inspected without opening anything up. This is the most common assessment and the baseline that satisfies the Fire Safety Order for the common parts of a block or HMO.
A Type 1 looks at the parts everyone depends on to get out: the protected staircase, the fire doors onto it, the compartmentation between flats and the escape route, detection and emergency lighting in the shared areas, and how the building is managed. For the large majority of standard blocks and HMOs, this is the assessment that's needed.
I carry out Type 1 assessments.
Type 2 — common parts, destructive
The same scope as a Type 1, but with destructive inspection — opening up parts of the structure (for example, sections of ceiling, riser cupboards or wall build-ups) to check fire protection that's normally concealed.
A Type 2 is the exception, not the rule. It's usually commissioned where there's specific reason to doubt the concealed compartmentation — after a fire, during major refurbishment, or where a previous assessment flagged a concern that can only be resolved by looking inside the fabric.
This is intrusive work — I refer Type 2 assessments to assessors equipped for it.
Type 3 — common parts + a sample of flats, non-destructive
Everything in a Type 1, plus a non-destructive look inside a representative sample of the individual flats or let rooms. It considers fire safety within the dwellings — the flat entrance doors, detection inside, and the means of escape from the flat itself — as well as the common parts.
A Type 3 is used where there's reason to check what's happening inside the lettings, not just the shared areas — often in HMOs and rented blocks where the condition inside the units matters to the overall picture.
I carry out Type 3 assessments.
Type 4 — common parts + flats, destructive
The most extensive: a Type 3 scope with destructive inspection of both the common parts and a sample of the flats. It's reserved for buildings where there are serious, structure-level concerns about fire protection that can only be answered by opening up.
Like Type 2, this is specialist, intrusive work.
This is intrusive work — I refer Type 4 assessments to assessors equipped for it.
Which type do I need?
For most blocks and standard HMOs, a Type 1 — and that's what satisfies the Fire Safety Order for the common parts. A Type 3 is the right call where the inside of the flats or rooms needs to be considered too. Type 2 and Type 4 are the intrusive exceptions, commissioned only where concealed fire protection genuinely needs to be opened up and checked.
If you're not sure, that's normal — it's exactly the kind of thing to confirm before you book. Tell me about the building and I'll tell you honestly which type fits, and whether it's work I carry out or work I'd refer on.
Not sure which type your building needs?
Tell me about it and I'll confirm — no upfront payment, and a fixed price once we've pinned down the scope.
People also ask
Is a Type 1 fire risk assessment enough for my HMO?
For the common parts of most standard HMOs, yes — a Type 1 is the baseline the Fire Safety Order requires. A Type 3 is used where the inside of the let rooms also needs assessing. I'll advise which is right when you enquire.
What's the difference between Type 1 and Type 3?
A Type 1 covers the shared common parts only. A Type 3 covers the common parts plus a non-destructive sample of the individual flats or rooms. Both are non-destructive.
Do you do Type 2 and Type 4 assessments?
No — those are destructive, intrusive assessments that need different equipment and competence. I carry out Type 1 and Type 3, and refer the intrusive work to assessors set up for it. Honest scope is part of doing this properly.
Do these types apply to a shop or office?
No. The Type 1–4 framework is for residential buildings — blocks of flats and shared housing. A commercial premises is assessed to PAS 79-1 instead. See the business fire risk assessment page.
Find out which type you need.
Tell me about the building and get a fixed price — no upfront payment.