What is a higher-risk building?

In England, a higher-risk building is a building that is at least 18 metres high or has at least 7 storeys, and that contains at least two residential units (GOV.UK). A flat counts as a residential unit whether it is owned, privately rented or social rented. If your building meets both tests, work inside your flat may need approval from the Building Safety Regulator (BSR).

The three questions to ask

1. What is the building used for? Most residential blocks qualify. Mixed-use buildings count too: a block with shops below and two or more homes above can be higher-risk. Serviced apartments count, and so does a short-term let, which is treated as a residential unit.
2. Is it tall enough? It needs to reach 18 metres or 7 storeys. It does not need to meet both.
3. What counts as one building? Attached structures are generally treated as one building. A section with its own entrance and exit and no access to another residential section can be treated as a separate building, so a tower on a shared podium may be assessed on its own.

How height and storeys are counted

The regulations set a method, so estimates are not enough. Storeys below ground level are ignored, as are rooftop levels that contain only plant or machinery. An open roof garden is not a storey, which is the government's stated position, although a 2024 tribunal decision took a different view and the government has said it is consulting on a change to make this explicit. A gallery or mezzanine only counts if its floor area is at least half that of the largest storey above or below it. Height is measured from ground level to the top of the floor surface of the top storey.

Buildings that are excluded

A building used entirely as a hospital, care home, secure residential institution, hotel or military barracks is not higher-risk, however many units it has. Hostels used as hotels are treated as hotels.

Why it matters

The higher-risk regime changes who oversees building work. If your building qualifies, the BSR is the building control authority and you need approval before most building work starts. Read Do I need BSR approval to refurbish a flat in a high-rise block? for what that means in practice.

This definition applies to the higher-risk regime only. Other rules, such as the leaseholder protections under the Building Safety Act, use a different definition of building.

Check yours

See How do I find out whether my building is higher-risk?, then try the BSR screener.

Source: GOV.UK, Criteria for being a higher-risk building during the occupation phase, last updated 28 May 2025.