What is a type 4 fire risk assessment?

If your fire risk assessor recommends a “type 4” for a block of flats, they are asking for something far more involved than the usual yearly assessment. Here is what the four types are, why type 4 is unusual, and how it relates to a compartmentation survey.

Where the four types come from

The types are set out in Fire Safety in Purpose-Built Blocks of Flats, the national guide produced in 2011 for the Local Government Association and still published on GOV.UK with update notes. The guide itself says it reflects the law and practice of the time and that a revised version is planned, so treat it as the shared vocabulary rather than the last word. Assessors, housing providers and managing agents still use its four types every day.

The types differ on two questions: does the assessment go inside the flats, and does it open up the construction?

Type 1: the baseline

A type 1 covers the corridors, stairs, plant rooms and other common parts, plus a look at a sample of flat entrance doors, without breaking anything open. The guide describes it as the basic assessment for meeting the Regulatory Reform (Fire Safety) Order 2005, and for most blocks it is where assessment starts.

Since the Fire Safety Act 2021, the structure, external walls and flat entrance doors of a block of flats are clearly inside the scope of the Fire Safety Order, so a type 1 has to consider them, even if it cannot see behind them.

Type 2: opening up the common parts

A type 2 has the same scope as a type 1 but includes some destructive inspection on a sampling basis: lifting ceiling tiles, opening service risers and boxing, looking above suspended ceilings. It is usually a one-off, done when the assessor has reason to think fire separation behind the surfaces may be poor.

Type 3: going into flats

A type 3 adds a non-destructive look inside a sample of flats, checking things like escape routes within the flat and smoke alarms. The guide notes it goes beyond what the Fire Safety Order requires and that it may sometimes suit rented flats where there is reason to suspect serious risk. It is often not possible in long leasehold flats, because the freeholder normally has no right of access.

Type 4: the full picture

A type 4 combines both: common parts and flats, with sampled opening-up in each. The assessor is checking whether a fire in one flat would stay there, which means looking at the fire separation between flats and between flats and the common parts.

The guide is clear that type 4 is for limited circumstances. Its example is a new landlord taking over a block where the history of works is unknown and there is reason to suspect serious risk from a fire in a flat. Other common triggers are:

• a building with many unrecorded alterations, such as new kitchens, bathrooms or extra flats;
• a type 1 or type 2 that found serious defects in fire separation;
• a change in evacuation strategy, for example from stay put to simultaneous evacuation, being considered;
• a conversion where the original standards are unclear.

How it differs from a compartmentation survey

The overlap causes a lot of confusion.

• A type 4 fire risk assessment is a risk assessment: it looks at all fire risks, including ignition sources, escape, alarms and management, as well as fire separation, and reaches a judgement on the risk.
• A compartmentation survey looks only at the fire-resisting walls, floors, doors and service penetrations, in detail, and produces a defect schedule with a photo, location and fix for every breach.

Many clients do both together: the type 4 assessment decides what level of risk the building carries, and the survey records every defect so a contractor can price the fire stopping and remediation. Some surveyors are also fire risk assessors; others specialise in passive fire protection only. A good survey report gives annotated floor plans and a risk rating for each issue.

Practical points before you commission one

1. Access. You will need agreement from residents for every flat in the sample, and in leasehold blocks that can take weeks. Start early and keep records of every request.
2. Asbestos. Get the asbestos information for the areas to be opened before anyone drills or lifts.
3. Making good. Agree who repairs the openings and to what standard.
4. Sample size. Agree how many flats and which types, so the result is representative.
5. What happens next. Budget for remedial work. A type 4 is rarely the end of the spending.

What it costs

There is no published price list. As a guide to scale, public contracts for compartmentation surveys alone have ranged from about £14,600 for one NHS site to £82,692 for one hospital wing, and the City of London published £68,370 for intrusive surveys and fire stopping at two blocks on the Barbican Estate. See the cost guide for the full list.

This bulletin is general guidance, not legal or fire engineering advice. Your fire risk assessor should recommend the type of assessment your building needs.