Higher-risk buildings: 18 metres and Planning Gateway One
The 18 metre and seven storey thresholds decide whether a scheme needs a fire statement and consultation with the Building Safety Regulator.
A higher-risk building is one that meets a height condition and contains residential accommodation, and the definition matters at planning stage because it is what pulls a scheme into Planning Gateway One. The higher-risk building definition used for the building control regime under the Building Safety Act 2022 turns on a building being at least 18 m in height or having at least seven storeys, and containing at least two residential units.
Planning has its own trigger, expressed in the Development Management Procedure Order. It is close to the building control test but not identical, and confusing the two is the commonest mistake on a validation checklist.
How the height condition works
Height is measured from ground level to the floor surface of the top storey of the building, ignoring any storey that consists only of plant or machinery rooms.
Storeys are counted excluding those below ground level. A building with a basement car park, six residential floors and a rooftop plant enclosure will usually count as six storeys, and its height will be measured to the floor of the sixth.
Two details cause arguments. Where the ground slopes, the measurement is taken from the lowest ground level adjoining the building, which can push a scheme over the threshold on a sloping site even though it looks lower from the street. And a mezzanine may or may not count as a storey depending on how it is formed, so resolve it with the building control body early rather than at submission.
What triggers Planning Gateway One
Article 9A of the Town and Country Planning (Development Management Procedure) (England) Order 2015 requires a fire statement to accompany applications for relevant development.
Relevant development is, in outline, development involving a building that contains two or more dwellings or educational accommodation, and which meets the height condition of 18 m or more, or seven or more storeys. It catches full applications and reserved matters where the building meets that description.
The practical consequences are three. The application is invalid without a fire statement on the published form. The Health and Safety Executive becomes a statutory consultee and its response has to be taken into account. And the fire strategy has to be developed far enough at planning stage to answer questions about siting and layout, which is earlier than many design teams are used to.
What the fire statement has to address
The form is structured around the matters the Health and Safety Executive looks at, and they are planning-stage matters rather than detailed building control ones.
| Theme | What the statement covers |
|---|---|
| Siting | Access for fire appliances, hard standing, hydrants and water supply |
| Layout | Escape routes, protected areas, distance to boundaries and to other buildings |
| Materials | The principles of the external wall construction, at the level of design fixed at planning |
| Access | How the emergency services reach and operate around the building |
| Ongoing use | How the design supports evacuation and firefighting once occupied |
Answer the questions at the level of detail the design has actually reached, and say what remains to be developed at Gateway Two. A statement that promises everything and evidences nothing gets a holding response from the regulator, and a statement that copies a building regulations strategy misses the point in the other direction.
Site layout is where planning and fire safety collide hardest. Appliance access routes need width, headroom, turning space and a bearing capacity that a landscape-led courtyard design will not deliver by accident, and pumping distances to the furthest part of the building constrain where the cores can sit. None of that is visible on a massing model. Resolve those with the fire engineer at the massing stage. Retrofitting a fire appliance route into an approved layout usually means losing units.
The Building Safety Regulator as consultee
The Building Safety Regulator sits within the Health and Safety Executive and is the statutory consultee for Gateway One. It reviews the fire statement and advises the local planning authority, which remains the decision maker.
Its comments arrive as advice rather than direction, but a local authority that grants permission against clear regulator advice is exposed on appeal and on judicial review, so in practice the advice carries weight. Where the regulator raises a point, the sensible response is to amend the scheme or provide the missing information rather than to argue that planning is not the place for it.
Gateway One is only the first of three. Gateway Two is the pre-construction approval by the regulator under the building control regime, and Gateway Three is the completion stage. Planning does not discharge either.
Programme for that. Gateway Two runs on its own statutory timetable and work cannot start until it is approved, so a permission granted in the expectation of an immediate start can sit unused for months. Developers who treat the planning decision as the point at which the ground opens are the ones caught out.
Why fire-engineering competence is required
The fire statement is a fire-engineering document and it has to be prepared by someone with the competence to write it. That is a legal expectation under the Building Safety Act 2022 framework and the Article 9A procedure, not a matter of preference.
An AI-drafted document can organise the planning narrative, set out the policy context and identify what information the form requires. It cannot substitute for a competent fire engineer, and a Fire Statement or a Fire Safety Strategy must be reviewed and signed off by one before submission. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval, and for specialist technical reports qualified professional input may be required.
Where the threshold catches schemes unexpectedly
Three situations recur.
Upward extensions of existing blocks of flats, whether under a prior approval route or a full application, can take a building over 18 m or over seven storeys. The permitted development rights covering upward extensions do not switch off the building safety regime that follows, and the design has to be tested against the height condition before the route is chosen.
Student accommodation and other educational accommodation is caught by the planning trigger even where the residential unit definition would not obviously apply, so check the wording of Article 9A rather than assuming the building control test answers it.
Mixed-use schemes with commercial floors at the base are measured as a whole building, so a podium of retail below seven residential storeys is unlikely to escape the threshold.
An illustrative example. A scheme of 24 flats over six residential storeys above a ground floor of commercial units, on a site falling 1.5 m across its width, measures 18.4 m from the lowest adjoining ground level to the top floor surface. It is relevant development, needs a fire statement, and triggers consultation with the regulator. Those figures are illustrative only.
Check which supporting documents a scheme of this scale needs before you set the planning programme, because the fire statement is the item that most often arrives late.
This is general guidance, not legal advice. Check the position with your local planning authority or a qualified fire engineer before relying on it.
Frequently asked questions
How is the 18 metre height measured?
From ground level to the floor surface of the top storey of the building, ignoring any storey consisting only of plant or machinery rooms. Where the ground slopes, the measurement is taken from the lowest ground level adjoining the building, which can push a scheme over the threshold on a sloping site.
What is Planning Gateway One?
It is the planning stage of the building safety regime. Article 9A of the Development Management Procedure Order 2015 requires a fire statement to accompany applications for relevant development, and makes the Health and Safety Executive a statutory consultee. The application is invalid without a fire statement on the published form.
Which applications count as relevant development?
In outline, development involving a building that contains two or more dwellings or educational accommodation and which meets the height condition of 18 metres or more, or seven or more storeys. It applies to full applications and to reserved matters. Check the wording of Article 9A rather than relying on the building control definition.
Does the regulator decide the application?
No. The Building Safety Regulator, which sits within the Health and Safety Executive, advises the local planning authority, and the council remains the decision maker. In practice the advice carries weight, because granting permission against clear regulator advice leaves an authority exposed on appeal and on judicial review.
Who can prepare a fire statement?
Someone with fire-engineering competence. The fire statement is a fire-engineering document and preparing it is not a drafting exercise. Software or a planning consultant can organise the narrative and identify what the form requires, but the technical content must be produced or signed off by a competent fire engineer before submission.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.