Higher-risk buildings: who counts, and what changes at 18 metres

A line drawn at a height changes how a building is governed. Cross it, and the Building Safety Act 2022 brings the block into the higher-risk regime, with a named Accountable Person, registration before occupation, a safety case and the oversight of the Building Safety Regulator. Stay below it, and the building is still governed by fire safety law, but the heavier machinery does not apply. So the threshold question is the first one to settle for any block you manage.

The definition, exactly

Under the Building Safety Act 2022, a higher-risk building in England is one that is at least 18m tall or has at least 7 storeys, whichever is reached first, and contains at least two residential units. The "whichever first" matters. A building can be a higher-risk building on storey count before it reaches 18m, and it can reach 18m on fewer than seven storeys where ceilings are tall. You do not get to pick the more convenient measure.

The Fire Safety (England) Regulations 2022, in force 23 January 2023, use the same high-rise residential threshold of 18m or seven storeys with at least two domestic premises for their additional duties, so the two regimes line up on height. That alignment is convenient, because a building over the line tends to attract both sets of obligations at once.

Who is excluded

Not every tall building with people sleeping in it counts. Hotels, care homes and secure or military accommodation are excluded from the occupation-phase higher-risk building definition under the Act. The logic is that the occupation-phase regime is built around residents in their own dwellings, with the resident engagement and safety case duties that follow from that. A hotel is governed by fire safety law and its own standards, but it is not registered as a higher-risk building for occupation.

This is a common point of confusion, because a 22-storey hotel plainly poses high-rise risks. It does. It is simply governed through a different route, not the Accountable Person and safety case route.

What changes once a building counts

Crossing the threshold is not a paperwork formality. A set of standing duties attaches.

• The building must be registered with the Building Safety Regulator before it is occupied.
• An Accountable Person, and a Principal Accountable Person where there are several, must be identified.
• A safety case must be prepared and a safety case report produced on request.
• The golden thread of digital information must be kept current through occupation.
• Under the Fire Safety (England) Regulations 2022, the responsible person must share external wall system and floor plan information electronically with the local fire and rescue service, keep hard-copy floor plans and a single-page orientation plan with contact details in a secure information box, and carry out monthly checks of firefighters' lifts and key firefighting equipment.

That last set of duties is worth separating out, because the monthly cadence is the part that lapses most easily. We look at it in detail in monthly checks that keep a high-rise compliant.

Measuring height and counting storeys

The threshold sounds precise, and it is, but applying it to a real building takes care. Height is measured from ground level to the floor of the top occupied storey, by the convention the regime uses, not to the parapet or plant room. Storeys are counted on the same basis, with rooftop plant and certain below-ground levels treated by specific rules. Mezzanines, split levels and sloping sites all complicate the count.

The practical advice is to get the measurement recorded properly once, with the basis written down, rather than carrying an approximate figure that someone later disputes. A building sitting close to the line deserves a documented determination, because the difference between 17.6m and 18.2m is the difference between two regulatory worlds.

A short comparison

The distinction is easiest to hold by contrast. A high-rise residential higher-risk building, triggered by 18m or seven storeys with at least two residential units, must register with the Building Safety Regulator before occupation, carries Accountable Person duties, and needs a safety case. A building that is tall but excluded, a hotel, a care home, secure accommodation, or one that simply sits below the line, does none of those things. On every one of those points the answer flips.

What does not flip is fire safety law. "Not a higher-risk building" never means "not governed". The Regulatory Reform (Fire Safety) Order 2005 applies to the responsible person regardless of height, and the fire risk assessment is required either way.

Why the boundary work is worth doing

Getting the classification right is the cheapest compliance work you will do, because everything downstream depends on it. Register a building that did not need it and you have created duties from nothing; miss one that did and you are operating outside the regime entirely. For a mixed portfolio, the first task is to sort each block against the threshold and record the determination, so the question is answered once rather than relitigated every time a new manager arrives.

SAMRISK holds each building's height, storey count and classification on its record, alongside the assessments and the compliance calendar that follow from it, so the threshold decision and its consequences stay together. You can see how buildings are organised on the buildings page. As ever, this is general guidance rather than legal advice, and a building near the line should be assessed on its specific measurements before anything is registered or assumed.