When Should You Choose a Type 2 or Type 4 Fire Risk Assessment?

For block managers responsible for residential flats, commissioning the correct type of fire risk assessment is not simply a compliance exercise. It is a practical decision about how well you understand the building you manage and how confidently you can demonstrate that fire risk has been properly assessed.

Most purpose-built blocks of flats are adequately covered by a Type 1 fire risk assessment. However, there are situations where a non-intrusive inspection cannot provide sufficient certainty about how a building will perform in the event of a fire. In these cases, a more detailed, intrusive assessment may be required. This is where Type 2 and Type 4 fire risk assessments become relevant.

Types of Fire Risk Assessments in Brief

Fire risk assessments for blocks of flats are commonly categorised into four types, based on the extent of inspection:

• Type 1: Common parts only, non-destructive

• Type 2: Common parts only, destructive

• Type 3: Common parts and flats, non-destructive

• Type 4: Common parts and flats, destructive

The scope of the assessment should always be proportionate to the building, the level of risk, and the amount known about the construction. Type 2 and Type 4 assessments are intrusive and should not be routine, but they provide the most detailed understanding of fire spread risk.

What Is a Type 2 Fire Risk Assessment?

A Type 2 fire risk assessment has broadly the same scope and objectives as a Type 1 assessment, focusing on the common parts of the building such as stairwells, corridors, service risers, and plant rooms. The key difference is that a Type 2 assessment includes destructive inspection, carried out on a sampling basis.

This means opening up elements of the building fabric to examine compartmentation, fire stopping, and the integrity of separating construction between flats and common areas. It will usually require a competent contractor to carry out the opening-up works and make good afterwards.

In some cases, destructive inspection may include a limited sample of flats, but this is often only possible in vacant units due to access constraints.

A Type 2 fire risk assessment is normally a one-off exercise, commissioned only where there is good reason to suspect serious structural fire safety deficiencies that could allow fire or smoke to spread beyond the flat of origin.

When Is a Type 2 Assessment Appropriate?

You would typically consider a Type 2 assessment where there is clear justification, such as:

• Evidence or strong suspicion of inadequate compartmentation or poor fire stopping

• Unauthorised or poorly documented historic works

• Conflicting or missing construction information

• Findings from a Type 1 fire risk assessment that cannot be verified visually

• Concerns raised through a FRAEW, EWS1, or similar survey

• Uncertainty around construction type, particularly in complex or mixed-use buildings.

The age of a building alone is not sufficient reason to commission a Type 2 assessment. Many older blocks perform well in fire safety terms, while some newer buildings may conceal significant defects.

What Is a Type 4 Fire Risk Assessment?

A Type 4 fire risk assessment is the most comprehensive form of assessment for a block of flats. It has the same scope as a Type 3 assessment, covering both the common parts and the flats, but it also includes destructive inspection in both areas.

This allows confirmation of how effectively flats are separated from one another, how compartment floors and walls are constructed, and how fire could spread between dwellings. As with Type 2 assessments, destructive inspection is carried out on a sampling basis and often requires vacant flats.

Type 4 assessments are disruptive and resource-intensive, but they provide the highest level of certainty.

When Is a Type 4 Assessment Appropriate?

Type 4 fire risk assessments are only suitable in limited and higher-risk circumstances, including:

• A new landlord or managing agent taking control of a block with an unknown construction history

• Serious concerns about resident safety from fires originating in neighbouring flats

• Widespread unauthorised alterations suspected across multiple dwellings 

• Buildings over 18 metres where construction details cannot be reliably confirmed

• Inconclusive findings from previous assessments where uncertainty remains 

• Situations where evidence-based reassurance is required rather than assumption.

Why Intrusive Surveys Add Real Value

While intrusive fire risk assessments should never be commissioned without reason, it is important to recognise that an intrusive survey provides the most in-depth analysis of potential fire spread within a building.

Non-destructive assessments inevitably rely on assumptions, even when informed by experience and drawings. Intrusive surveys remove much of this uncertainty by allowing the assessor to see how the building is actually constructed, rather than how it is believed to be constructed.

They allow confirmation of compartment walls, floor build-ups, service penetrations, fire stopping quality, and junctions that are otherwise hidden. For block managers, this clarity can be invaluable when making decisions that directly affect resident life safety.

Avoiding Superficial “Intrusive” Inspections

It is crucial to understand that a meaningful intrusive survey is not simply unscrewing socket plates, lifting a ceiling tile, or drilling a small hole and inserting a borescope camera. These methods may provide limited information, but they are rarely sufficient on their own.

Fire spread routes are often complex and occur at junctions and within voids that cannot be adequately assessed through small inspection points. A drill hole may show a material, but it will not demonstrate continuity, workmanship quality, or hidden defects.

A proper intrusive fire risk assessment involves planned, targeted opening-up of construction, based on risk and informed professional judgement.

Working With the Right Contractor

Intrusive surveys must always be carried out in partnership with a competent contractor. The contractor’s role is to open up the required areas safely and reinstate them to a reasonable standard. Poor making-good can introduce new risks and undermine the process.

Before any destructive inspection takes place, the risk of disturbing asbestos must be considered, including reference to the asbestos register and, where necessary, further surveys.

Final Thoughts for Block Managers

Intrusive fire risk assessments are not default solutions, but when used appropriately, Type 2 and Type 4 assessments provide clarity, confidence, and evidence. They remove assumptions, reduce uncertainty, and support sound, defensible fire safety decisions.

For block managers, the decision to commission an intrusive assessment is ultimately about understanding the building you are responsible for and ensuring that fire safety is based on evidence rather than expectation.

Simplify your path to full compliance. Contact us for a detailed, tech-led Intrusive Fire Risk Assessment.