Higher-Risk Buildings: Definition, Criteria, and What It Means for Building Managers

TL;DR: A higher-risk building under the Building Safety Act 2022 is a building in England that is at least 18 metres tall or has at least 7 storeys, and contains at least two residential units. If your building meets this definition, you are subject to the full Part 4 regime -- including registration with the Building Safety Regulator, Accountable Person duties, mandatory occurrence reporting, and the Golden Thread. Here is exactly what the criteria mean and what they require of you.

Check if your building qualifies as higher-risk

#What Is a Higher-Risk Building?

A higher-risk building under the Building Safety Act 2022 must be at least 18 metres in height or at least 7 storeys tall, contain at least two residential units, and be located in England.

— Building Safety Act 2022, Part 4

A higher-risk building is a residential building in England that is at least 18 metres tall or has at least 7 storeys, and contains at least two residential units. This definition, set out in section 65 of the Building Safety Act 2022, determines which buildings fall under the full Part 4 safety regime including registration, Accountable Person duties, and the Golden Thread.

Section 65 of the Building Safety Act 2022 gives the Secretary of State power to define higher-risk buildings by regulations. The Higher-Risk Buildings (Descriptions and Supplementary Provisions) Regulations 2023 set out the specific criteria:

A building is a higher-risk building if it:

1. Is at least 18 metres in height or has at least 7 storeys, and
2. Contains at least two residential units

Both conditions must be met. A 20-storey office block with no residential units is not a higher-risk building under the Act. A 5-storey block of flats is not a higher-risk building, even if it has 100 residential units. The regime targets tall residential buildings specifically -- the category of buildings where fire spread and structural failure pose the greatest risk to life.

#How Height Is Measured

The measurement matters because a building near the threshold could fall in or out of the regime depending on how you measure it. The Regulations specify:

• Height is measured from ground level to the top of the floor surface of the highest storey of the building
• Ground level is the lowest level of ground adjacent to the outside of the building
• The roof is not included in the measurement -- it is the floor surface of the top storey, not the ridge or parapet

This differs from some planning measurement conventions, which may measure to the roof ridge. For building safety purposes, it is the floor of the highest storey that counts.

#How Storeys Are Counted

The 7-storey threshold is an alternative to the 18-metre test -- a building qualifies if it meets either criterion. When counting storeys:

• All storeys count, including below-ground storeys (basements) that contain a dwelling or common parts
• Mezzanine levels count as storeys if they are a significant part of the floor area
• Gallery levels and partial floors require judgement -- consult the BSR guidance if uncertain

A building with 6 above-ground storeys plus a basement containing common parts (such as a plant room or bin store) has 7 storeys and qualifies.

#Mixed-Use Buildings

Many higher-risk buildings are not purely residential. A common configuration in urban areas is commercial on the ground floor (retail, offices, restaurants) with residential above. The key question is whether the building contains at least two residential units.

If it does, the entire building is subject to the higher-risk building regime -- including the commercial portions. The Accountable Person duties apply to the common parts of the whole building, not just the residential section.

This creates an important obligation for building managers: commercial leaseholders may not be directly subject to the Building Safety Act, but the building's safety arrangements must account for the risks their operations create (cooking extraction, waste storage, public access) and how those risks interact with the residential portions.

#What Makes a Building Stop Being Higher-Risk

A building can also lose its higher-risk status. If a building is converted so that it no longer contains at least two residential units -- for example, conversion to a hotel or office use -- it would no longer meet the definition. Similarly, if structural changes reduce the building below 7 storeys and 18 metres, the regime would cease to apply.

Building height is measured from ground level to the floor surface of the top storey, not to the roof. This measurement method is prescribed in the regulations and determines whether a building falls within scope.

However, conversion is rare for buildings of this scale, and the PAP should not assume the regime will cease to apply without confirming with the BSR. De-registration requires notifying the BSR and providing evidence that the building no longer meets the criteria.

#Registration: Your First Obligation

If your building is a higher-risk building, it must be registered with the Building Safety Regulator. Registration is the Principal Accountable Person's responsibility under section 77.

Higher-risk building status triggers the full Building Safety Act Part 4 regime: mandatory registration, Accountable Person duties, Golden Thread requirements, Safety Case Reports, and Building Assessment Certificates.

#The registration deadline has passed

The BSR required all existing higher-risk buildings to be registered by 1 October 2023. If your building is not yet registered, treat this as urgent -- failure to register is itself a compliance breach.

For buildings that have been newly built or have newly qualified (for example, through change of use or additional storeys), registration must happen before the building is occupied or as soon as reasonably practicable after the change.

#What registration involves

Registration requires providing the BSR with Key Building Information (KBI), including:

• The building's address, height, and number of storeys
• Number and type of residential units
• Construction type and structural materials (including cladding systems)
• Fire safety systems (detection, suppression, compartmentation)
• Details of the Accountable Person(s) and their contact information
• The status of any fire risk assessment and remediation work

The KBI requirements are detailed, and gathering the information for older buildings can be time-consuming. Start with what you have and update the registration as you obtain more accurate information. The BSR expects progress, not perfection, but it does expect the registration to exist.

For a comparison of who is responsible for registration versus other duties, see our article on Accountable Person vs Principal Accountable Person.

#The Part 4 Regime: What Applies to Your Building

Once your building is classified as higher-risk and registered, the full Part 4 obligations of the Building Safety Act apply. This section summarises what that means for day-to-day management.

#Accountable Persons and the PAP

Every higher-risk building must have at least one Accountable Person and a designated Principal Accountable Person. The AP is anyone holding a legal estate in the building's common parts or with a repairing obligation. The PAP is the AP who holds the legal estate in the structure and exterior -- typically the freeholder.

For a detailed breakdown of these roles and their duties, see our AP duties explainer and PAP responsibilities guide.

#The Golden Thread

The Golden Thread is the complete, accurate, digital record of all building safety information. For higher-risk buildings, maintaining the Golden Thread is a legal requirement under section 88 and the Higher-Risk Buildings (Keeping and Provision of Information) Regulations 2024.

This includes structural records, fire safety system documentation, maintenance histories, contractor certifications, risk assessment findings, and records of remediation work. The records must be digital, up to date, and accessible to relevant persons.

#Building Assessment Certificate

The BSR will call in higher-risk buildings for assessment over time. When called, the PAP has 28 days to apply for a Building Assessment Certificate (BAC) under section 78. The BAC assessment evaluates whether the building is being managed safely and whether the PAP is fulfilling their obligations.

Preparing a Safety Case Report in advance is one of the most important steps for BAC readiness, as it forms a core part of what the BSR evaluates.

#Mandatory occurrence reporting

Higher-risk buildings are subject to mandatory occurrence reporting under section 87. Certain safety events -- structural failures, fire spread beyond the room of origin, failure of fire safety systems -- must be reported to the BSR as soon as they are identified, with a written report following within 10 working days.

#Financial implications

The higher-risk building classification also has financial management implications. Service charges for higher-risk buildings must account for compliance costs -- risk assessments, Golden Thread maintenance, specialist contractors, BSR engagement, and Safety Case Report preparation. These are not discretionary expenses; they are costs of meeting your legal obligations. A building safety compliance platform can help you track these obligations systematically and demonstrate compliance when the BSR calls your building in for assessment.

For buildings subject to section 20 consultation requirements, major safety works may trigger leaseholder consultation. Understanding the intersection of building safety obligations and service charge law is essential for transparent financial management.

#Making It Concrete: A Borderline Building

Consider Maple Court, a residential building that appears to have 6 storeys above ground. The managing agent has assumed it falls outside the higher-risk regime. But on closer inspection:

• The building has a basement level containing a plant room, bin store, and residents' cycle storage -- all common parts
• Ground level on the south side is 1.2 metres lower than the north side due to the site slope
• Measuring from the lowest ground level to the top floor surface gives a height of 18.3 metres

Maple Court qualifies as a higher-risk building on both counts: 7 storeys (including the basement) and over 18 metres (measuring from the lowest adjacent ground level). The managing agent's assumption was wrong because they did not count the basement or measure from the correct ground level.

This scenario is common. Many buildings near the threshold are borderline. If your building is close to 18 metres or 7 storeys, measure carefully using the statutory method. Getting it wrong in either direction is problematic: treating a qualifying building as exempt means you are not meeting your legal obligations, while treating a non-qualifying building as higher-risk wastes resources on obligations that do not apply.

#Frequently Asked Questions

#What is a higher-risk building under the Building Safety Act?

A higher-risk building is a building in England that is at least 18 metres in height or has at least 7 storeys, and contains at least two residential units. This definition is set out in section 65 of the Building Safety Act 2022 and further specified in the Higher-Risk Buildings (Descriptions and Supplementary Provisions) Regulations 2023.

#How is the height of a higher-risk building measured?

Building height is measured from ground level to the top of the floor surface of the highest storey of the building. Ground level means the lowest level of ground adjacent to the outside of the building. This measurement method is specified in the Higher-Risk Buildings (Descriptions and Supplementary Provisions) Regulations 2023 and differs from some other measurement conventions used in planning.

#Do higher-risk buildings need to be registered with the Building Safety Regulator?

Yes. All higher-risk buildings must be registered with the Building Safety Regulator (BSR). The initial registration deadline was 1 October 2023. The Principal Accountable Person is responsible for registration under section 77 of the Building Safety Act. Any building that newly qualifies as higher-risk must be registered promptly.

#Are mixed-use buildings included in the higher-risk building definition?

Yes, if the building meets the height or storey threshold and contains at least two residential units. A building with commercial units on the ground floor and residential flats above still qualifies if it is at least 18 metres tall or has at least 7 storeys. The residential units trigger the regime; the presence of commercial space does not exempt the building.

#What obligations apply to higher-risk buildings that do not apply to other buildings?

Higher-risk buildings are subject to Part 4 of the Building Safety Act 2022, which includes: registration with the BSR, designation of Accountable Persons, the Building Assessment Certificate process, mandatory occurrence reporting, the Golden Thread of building information, Safety Case Reports, and residents' engagement strategies. These obligations do not apply to buildings below the height and storey thresholds.

#Further Reading

• Accountable Person vs Principal Accountable Person -- understanding who holds which role in your building
• Accountable Person Duties Under the Building Safety Act -- detailed AP obligations
• Building Safety Act Complete Guide -- comprehensive overview of the full BSA regime
• The Complete Golden Thread Guide -- how to set up and maintain your building information record
• Section 20 Consultation and the Building Safety Act -- financial obligations for major safety works
• Golden Thread in Practice -- building a digital audit trail for your building
• BSR Assessment: How to Prepare -- preparing for your BSR assessment
• Fire Risk Assessment Tracking -- tracking FRA actions for your building
• Building Assessment Certificate Guide -- the BAC process for higher-risk buildings

This article is for informational purposes. For building-specific advice, consult a qualified fire safety professional.

Check if your building qualifies as higher-risk -- try our free Building Checker tool