Glossary
Higher-Risk Building.
A residential building of at least 18 metres or seven storeys, with at least two residential units, under the Building Safety Act 2022 occupied-buildings regime. Subject to Principal Accountable Person duties, the building safety case requirement, and Building Safety Regulator oversight.
How the HRB threshold is measured.
The 18 metre measurement is from the lowest finished surface of the ground adjoining the outside of the building to the floor surface of the highest finished storey containing residential units. Storeys below ground level and storeys consisting only of plant or machinery do not count toward the seven-storey threshold. The two residential units threshold is met by any building with at least two flats, even if the rest of the building is not residential.
HRB definition for design vs occupation.
There are two HRB definitions in the BSA framework. The occupied-buildings regime uses the definition above. The design and construction regime (the three Gateways) uses a slightly broader definition that also includes care homes and hospitals at the same height threshold. The two definitions differ because the risks at the construction stage differ from the risks during occupation.