What is a higher-risk building? The two definitions, kept separate
Higher-risk building (HRB) sounds like one definition. It isn't. The Building Safety Act runs two regimes, one for buildings in occupation, one for buildings being designed and constructed, and they define an HRB differently. Using the wrong one is the most common mistake, so this page keeps them apart.
In occupation
An occupied building in England is a higher-risk building if it is at least 18 metres in height or has at least 7 storeys, and contains at least 2 residential units.
- How height is measured: to the top of the floor surface of the top storey; rooftop machinery and plant areas are excluded; on sloping ground, measured from the lowest part of the ground.
- How storeys are counted: exclude storeys below ground, storeys that are only rooftop plant or machinery, and gallery floors smaller than half the adjacent storey's area.
- Excluded uses: a building used entirely as a hospital, care home, secure residential institution, hotel or military barracks is not an in-occupation higher-risk building.
- Residential unit: a dwelling or any other unit of living accommodation, flats, studio flats, student accommodation, supported housing.
Legal duty, Building Safety Act 2022, s65 · Measurement, Higher-Risk Buildings (Descriptions and Supplementary Provisions) Regulations 2023 · BSR guidance, occupation-phase criteria
In design & construction
For a new building being designed or constructed, the threshold is the same, at least 18 metres or at least 7 storeys, but the qualifying uses are wider: a building with at least 2 residential units, or a care home, or a hospital.
Work to an existing building, including changes of use or adding storeys, has separate BSR guidance and additional building-definition considerations. This summary covers the new-building test; check the existing-building criteria separately.
- Key difference: care homes and hospitals are higher-risk buildings for design and construction, but not for the occupation regime.
- Cannot split: during design and construction, attached structures are treated as a single higher-risk building, you cannot split it by individual component thresholds. The occupation regime allows independent sections in defined cases.
Descriptions, Higher-Risk Buildings (Descriptions and Supplementary Provisions) Regulations 2023 · Procedures, Building (Higher-Risk Buildings Procedures) (England) Regulations 2023 · BSR guidance, design-and-construction criteria
Occupation vs design & construction, side by side
| In occupation | Design & construction | |
|---|---|---|
| Height / storeys | ≥18m or ≥7 storeys | ≥18m or ≥7 storeys |
| Residential units | ≥2 required | ≥2, or a care home, or a hospital |
| Hospitals / care homes | Excluded | Included |
| Excluded uses | hospital, care home, secure residential, hotel, barracks | secure residential, hotel, barracks |
| Attached structures | may be independent sections | single building (cannot split) |
| Regime | BSA 2022 Part 4 | building-control regime (Gateways) |
Try the higher-risk building checker, read the accountable person's duties, or go back to Building Safety Act compliance.
Higher-risk buildings, FAQs
Does a care home ever count as a higher-risk building?
Yes, but only in the design and construction regime. A care home meeting the height or storey threshold is a higher-risk building for design and construction. It is not a higher-risk building under the in-occupation regime, which is limited to buildings with at least 2 residential units.
Is it 18 metres or 7 storeys, and, or?
Either one meets the height/storey limb: a building at least 18 metres tall or with at least 7 storeys qualifies on that limb. You still need the use limb as well (residential units, or, in design and construction, a care home or hospital).
Does this definition apply in Wales?
No. Wales has its own separate regulations for higher-risk buildings. This page is about the England regime.