Episode 175 - Higher Risk Building Definitions

This week we will be talking about Higher Risk Building Definitions. This episode content meets PC3 - Legal Framework & Processes of the Part 3 Criteria.

Resources from today's episode:

Websites:

• https://www.architecture.com/knowledge-and-resources/knowledge-landing-page/what-are-the-key-considerations-for-architects-when-it-comes-to-hrb-definitions
• https://www.gov.uk/guidance/criteria-for-being-a-higher-risk-building-during-the-occupation-phase-of-the-new-higher-risk-regime
• https://www.gov.uk/guidance/scope-determination-appeal-appeal-to-the-secretary-of-state-under-section-101a-of-the-building-act-1984

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Transcript

Episode 175:

Hello and Welcome to the Part3 with me podcast. 

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I am your host Maria Skoutari and this week we will be talking about Higher Risk Building Definitions . Todays’ episode meets PC3 of the Part 3 Criteria.

Now, with the introduction of the Building Safety Act, the government acknowledged that further clarity was needed—especially around the definition of a Higher-Risk Building. In response, on the 28th of May 2025, the Ministry of Housing, Communities and Local Government issued updated guidance to help clarify things.

So, to be classified as a higher-risk building, a building must meet a certain set of use criteria, this is in addition to meeting the height or storeys threshold:

• So under the Building Safety Act 2022 and Higher Risk Buildings (Descriptions and Supplementary Provisions) Regulations 2023, a building is considered high risk if it:
• Is at least 18 metres in height or has at least 7 storeys and contains at least 2 residential units

Now relating to how this is measured, it should be taken from ground level to the top of the floor surface of the highest occupied storey of the building. Any storey which is a rooftop machinery or rooftop plant area or consists exclusively of rooftop machinery or rooftop plant rooms or where there is a rooftop garden or terrace, these should be excluded. Key item to consider here is assessing where ground level is for the building and measure from there. Any storeys below ground level should be excluded from the measurement. If a building is on uneven ground, height is measured from the lowest part of the ground surface that touches any part of the building. 

The understanding of the definition of a ‘building’ is important when measuring height. With a new building that cannot have independent sections, the measurement of height may be different to an existing building complex where ‘independent sections’ provide that the complex can be defined as several different ‘buildings’ whose height can be measured independently. Let’s say you have a large existing building that’s split into different parts—some with residential units, some without. If a section:

• Has its own external entrance and exit to the outside,
• Can be accessed independently from anywhere within, and either
• has no access to any other section within the overall structure or only has access to another section of the overall structure which does not contain a residential unit,

it can be treated as a separate building under the regulations.

This is important because independent sections:

• Can be registered separately as higher-risk buildings,
• Or, if they don’t contain residential units, they don’t need to be registered at all.

For example, work to an independent section that does not contain two residential units does not have to be approved by the Building Safety Regulator and can be approved by the local authority or a private Registered Building Control Approver (RBCA). It's important to understand however, that the concept of independent sections does not apply to new buildings that are either being constructed or designed.

If a part of an existing building complex meets the requirement for an independent section - then it can be treated as a separate ‘building’ for the purposes of the regulations. Independent sections allow separate registrations of two higher risk buildings within the same complex or would allow parts of the wider building complex that do not contain residential units not to be registered as higher risk buildings. This would mean for example, that work to an independent section that does not contain two residential units does not have to be approved by the Building Safety Regulator, but that the Local Authority or Private Registered Building Control Approver can be the approving authority.

I would suggest referring to the guidance which provides detailed diagrams of the various instances, I have provided a link to it in the episode notes. 

Now let’s run through which building types are excluded from the occupation part of the higher risk regime. These include buildings used entirely as:

• A care home 
• A hospital
• A secure residential institution
• A hotel
• Military barracks
• A building that contains living accommodation provided by the Ministry of Defence
• A building that contains living accommodation for His Majesty’s forces and/or any visiting force or an international headquarters or defence organisation designated for the purposes of the International Headquarters and Defence Organisations Act 1964.

So if working on any of these types, they’re not considered higher-risk once they’re occupied—even if they’re over 18m or have multiple storeys.

Now, there are slightly different definitions during the design and construction phase. During that phase the higher risk building definition is a little broader, meaning:

• Again, under the Building Safety Act 2022 and Higher Risk Buildings (Descriptions and Supplementary Provisions) Regulations 2023, a building is considered high risk when it:
• Is at least 18 metres in height or has at least 7 storeys and contains at least 2 residential units

But, the key difference here is, if a building meets those two criteria during the construction phase, then it is considered a higher risk building and this also includes care homes and hospitals. But once those phases are completed and the building is in the occupation phase, then care homes and hospitals are  no longer considered higher risk buildings. 

Confusing I know. So be wary of those instances if working on care homes or hospitals or if you have an exam question or coursework which tries to catch you out on the definitions. 

Now, a further clarification the guidance provides is that mixed-use buildings are covered by the higher-risk regime. For example, if a building contains a shopping centre but also has two residential units, then it is a higher-risk building, provided it meets the height or storeys threshold. Buildings such as boarding accommodation in schools and university accommodation would also be considered higher-risk buildings, provided they meet the height or storeys threshold for a higher-risk building, as they contain residential units.

Buildings that contain supported and sheltered accommodation are considered higher-risk buildings if they meet the height or storeys threshold, as they contain residential units. Examples of supported and sheltered accommodation which could fall under the higher-risk regime include domestic abuse refuges, children’s homes and supported or sheltered homes for older people and those with additional care needs which do not fall within the definition of a care home.

Now let’s dig into the provided definitions under the guidance to give you a better understanding of which facilities/uses fall under which category of building:

Staring with what is considered a Hospital and care home:

Hospitals are institutions for receiving and treating those who are ill, convalescing or need medical rehabilitation, or a maternity home.

Care homes provide accommodation, together with nursing or personal care, for those who are or have been ill, mentally unwell, or dependent on alcohol or drugs or who are disabled or infirm.

Buildings which are a hospital or a care home are not considered higher-risk buildings during occupation.

Buildings used for receiving and treating those who are ill, convalescing or need medical rehabilitation, or a maternity home without at least one bed for an overnight stay are not considered hospitals under the higher-risk regime. For example, a general practitioner surgery which does not allow overnight stays would not meet the definition of a hospital.

General note relating to hospitals and care homes, if construction work is carried out on existing hospitals or care homes that meet the height criteria, then they will be defined as higher risk buildings and any design and construction will have to be approved by the Building Safety Regulator. 

Now relating to secure residential institutions under the guidance they are defined as:

Buildings used entirely as secure residential institutions are excluded from the higher-risk regime. Secure residential institutions include prisons, young offenders’ institutions, detention centres, secure training centres, custody centres, short-term holding centres and secure local authority accommodation. If a building is used entirely for one of these purposes, then it is not a higher-risk building.

Moving on to hotels and other serviced accommodation under the guidance they are defined as:

Buildings used entirely as hotels are excluded from the higher-risk regime. Hotels are buildings which provide overnight accommodation for customers who stay for the purpose of leisure or business.

Hostels which also provide overnight accommodation to customers for leisure or business are considered as a type of hotel and so if a building is used entirely as a hostel, then it is not considered a higher-risk building. Hotels are excluded regardless of how long these buildings are occupied by individuals or groups of customers.

Serviced apartments do not fall within the meaning of hotel and are considered higher-risk buildings if they meet the height or storeys threshold.

A short-term let (for example, a short-term rental property let online) is considered a residential unit. If there was another residential unit within the building and the height or storeys threshold was met then the entire building, including the short-term let property, would be considered a higher-risk building.

And lastly relating to military premises under the guidance they are defined as:

Buildings used exclusively as military barracks are excluded from the higher-risk regime.

Buildings which contain any living accommodation either for His Majesty’s forces, any visiting forces or an international headquarters or defence organisation are also excluded.

So, ultimately, who has the responsibility for confirming if a project qualifies as a Higher Risk Building:

As stated within Part 2A of the Building Regulations, it is required that any Designer/Contractor, if requested to do so, must provide advice to the Principal Designer/Principal Contractor or the client on whether any design/work they are doing is higher-risk building. This means that all designers and contractors must understand the definitions and be able to advise the PD, PC and client accordingly.

Now if a local authority disagrees with the allocation and determination if a building is a Higher Risk Building, then they could refuse to determine the application following an initial notice or a building control application on the basis that it is or it contains higher risk building work.

There is a process, however, within the Building Safety Act 2022 to appeal this decision to the Secretary of State – known as a Scope Determination Appeal. There is a 28-day time limit for appealing from the date the local authority refused to deal with the application. The department then has eight weeks to respond to the appeal.

To sum up what I discussed today:

• On 28 May 2025 the government updated guidance to clarify the definition of a Higher-Risk Building (HRB).
• Higher-Risk Building status applies to residential buildings, including mixed-use, university accommodation, and sheltered housing. Care homes and hospitals are only Higher-Risk Buildings during design and construction, not once occupied. Hotels, hostels, secure institutions, and military accommodation are excluded.
• Designers and contractors must assess and advise whether their work involves Higher-Risk Buildings. If a local authority disagrees with a classification, it can refuse a building control application, which can then be appealed within 28 days.

That’s all for now. Thanks for tuning in, and we’ll catch you in the next episode.