IT IS A MEASUREMENT, NOT AN OPINION
Is your building a higher-risk building?
The Building Safety Act does not decide this by judgement. It measures your building against four tests, and all four have to line up. Here is how to work out which side of the line you are on.
The law defines it twice. The two definitions do not match.
WHERE THE PHRASE COMES FROM
"Higher-risk building" is a defined term in the Building Safety Act 2022. It is not a general description of risk, and no fire risk assessor can apply it to your building by opinion. A building either meets the statutory tests or it does not.
There are two definitions, and this is where most of the confusion starts.
The first covers buildings in occupation. Section 65 of the Act sets it, and it drives the Part 4 duties: registering with the Building Safety Regulator, the safety case report, the golden thread, resident engagement and mandatory occurrence reporting.
The second covers buildings being designed and built. Section 120D of the Building Act 1984 sets that one, and it drives the gateway process and building control approval through the Regulator rather than your usual building control body.
The height test is identical in both. What differs is which kinds of building count. In design and construction, care homes and hospitals are in scope. In occupation, they are not, because the Regulatory Reform (Fire Safety) Order 2005 already covers them.
So a hospital can be a higher-risk building on the Friday it is finished and not one on the Monday it opens. That is deliberate, not a drafting slip.
The height test is identical. What counts as a building is not.
SAME NUMBERS, DIFFERENT BUILDING
The Part 4 regime
Building Safety Act 2022, section 65
Height test
At least 18 metres, or at least 7 storeys. Either one is enough.
And it must contain
At least 2 residential units.
Excluded
Care homes, hospitals, secure residential institutions, hotels and military barracks, where the building is used entirely as one of those.
What follows if you are in
Register with the Building Safety Regulator, a safety case report, the golden thread, resident engagement, mandatory occurrence reporting.
The gateway regime
Building Act 1984, section 120D
Height test
At least 18 metres, or at least 7 storeys. Identical to the other column.
And it must be
A building with at least 2 residential units, a care home, or a hospital.
Excluded
Secure residential institutions, hotels and military barracks. Care homes and hospitals are not excluded here.
What follows if you are in
The gateway process, and building control approval from the Regulator rather than your usual building control body.
Care homes and hospitals are the ones that switch. They sit outside the occupation regime because the Regulatory Reform (Fire Safety) Order 2005 already covers them. The government confirmed that when it reviewed the definition, and left the thresholds where they are.
Work it out in four steps. Each one has a trap.
FOUR TESTS, NO PARTIAL CREDIT
STEP 01
Measure the height
The rule
From the lowest part of the ground next to the building, up to the top surface of the floor of the top storey. If that reaches 18 metres, the height test is met.
Where people go wrong
Not to the roof, and not to the ridge. Roof-top plant rooms and machinery are ignored. On sloping ground you measure from the low side, which pushes more buildings over the line than owners expect.
STEP 02
Count the storeys
The rule
Count upward from ground level. Seven or more and you are in, whatever the height comes out at.
Where people go wrong
Basements do not count. Roof-top plant does not count. A roof garden is not a storey. A gallery or mezzanine only counts if it is at least 50% of the floor area of the storey it sits in.
STEP 03
Count the residential units
The rule
You need at least two. A residential unit is a dwelling, or any other unit of living accommodation.
Where people go wrong
Tenure makes no difference. Owned, privately rented and social all count the same. Student accommodation and supported housing count. Two flats above a shop in a seven-storey block is enough.
STEP 04
Check the use
The rule
The building must not be used entirely as a care home, hospital, secure residential institution, hotel or military barracks.
Where people go wrong
That word "entirely" is the whole game. Serviced apartments are not hotels. A building that is mostly a hotel but holds two long-let flats is not entirely a hotel, so it is back in scope.
Three out of four is not a higher-risk building. But being outside Part 4 does not mean being outside everything. A building can fall outside the Building Safety Act and still carry duties under the Fire Safety (England) Regulations 2022, and those two get confused constantly. Run your building through the checker if you want the answer in under a minute.
Four things being higher-risk does not mean
WHERE PEOPLE TRIP UP
The myth
"Higher-risk means our building is dangerous."
The reality
It is a scope test, not a risk rating. It tells you which regime applies, not how safe your building is. A well-run 20-storey block is higher-risk. A neglected four-storey block is not. The label says nothing about the condition of the building.
The myth
"Higher-risk building and high-rise residential building are the same thing."
The reality
Same numbers, different laws. Higher-risk building is a Building Safety Act term and brings registration, the safety case report and the golden thread. High-rise residential building is a Fire Safety (England) Regulations 2022 term and brings secure information boxes, wayfinding signage, floor plans for the fire service and monthly equipment checks. Most buildings over the threshold are both, and each set of duties has to be done separately.
The myth
"We are under 18 metres, so none of this touches us."
The reality
Below the threshold is not the same as outside the law. Duties start biting at 11 metres: quarterly checks of communal fire doors and annual checks of flat entrance doors. The residential evacuation plan regulations that came into force in April 2026 also reach buildings over 11 metres on a simultaneous evacuation strategy. And some duties apply to every multi-occupied residential building at any height.
The myth
"The threshold is about to change, so there is no point acting yet."
The reality
The government reviewed the definition and left it exactly where it was: 18 metres or seven storeys. It committed to reviewing it at least annually, with a full review of the Act due in 2027. Waiting buys you nothing and the offences apply now.
GO DEEPER
KEEP READING
Interactive tool
Higher-risk building checker
Answer a handful of questions about your building and get an indicative answer on whether it falls inside the regime.
Check your building →
Plain-English guide
The Building Safety Act, explained
What the Act actually changed, who it made responsible, and what it means if your building is inside the regime.
Read the guide →
The duty that follows
What a building safety case is
If your building is in scope, this is the heaviest duty it brings. The work, the report, and why the two are not the same thing.
See the explainer →
Who holds it
Responsible Person vs Accountable Person
Two roles from two different laws. Which one you are, and why a higher-risk block usually has both at once.
See the explainer →
If this is you
Right to Manage directors
Taking over the management can move the building safety duties to your company, and take the freeholder out of the regime entirely.
See what sits with you →
Reference
Jargon Buster
Accountable Person, golden thread, safety case, gateway. Every term in this guide, in plain English.
Look up a term →
What is a higher-risk building? The definition, explained
Higher-risk is a measurement, not an opinion. The 18 metre and seven storey tests, what counts as a residential unit, and why it is not the same as a high-rise residential building.