External wall materials and combustibility at planning

The restriction on combustible cladding in external walls is a Building Regulations rule, not a planning one, and that gap is where architects get caught. Regulation 7(2) of the Building Regulations 2010 requires materials in the external walls of relevant buildings, and in specified attachments to them, to achieve European Class A2-s1,d0 or better. Planning controls what the elevation looks like. Building control decides whether it can lawfully be built. Submit a scheme whose approved materials cannot meet regulation 7 and you will be back for an amendment, at your cost.

What the restriction actually says

Regulation 7(2) applies to buildings with a storey at least 18 m above ground level that contain dwellings, institutions, rooms for residential purposes, student accommodation or, following the 2022 amendment, hotels, hostels and boarding houses.

For those buildings, materials that become part of an external wall, or of a specified attachment, must achieve Class A2-s1,d0 or Class A1 under BS EN 13501-1. Specified attachments include balconies, solar shading devices and solar panels fixed to the wall.

Separately, and for all buildings regardless of height or use, certain metal composite materials of the type implicated in past failures are prohibited outright.

Regulation 7(3) lists exemptions, and reading that list properly is worth an hour of anyone's time. Membranes, cavity trays, seals, gaskets, fixings, thermal breaks, window and door frames, glass and electrical installations are among them. Those exemptions are narrow and specific. They are not a general permission to include a small quantity of a combustible product.

Which buildings are caught, and which are not

The 18 m trigger is measured to the floor surface of the top storey above ground level, ignoring any storey consisting only of plant rooms.

Two related regimes use different triggers and are easy to confuse.

A block at 17.5 m to the top floor sits outside regulation 7(2) and outside Gateway One. It is still subject to Approved Document B on external fire spread, and to the authority's own design policies, so combustible cladding is not automatically acceptable there either.

Balconies, spandrels and the things drawn last

Balconies are the recurring problem. A balcony attached to the external wall of a relevant building is a specified attachment, which means the decking, the balustrade framing and the soffit are all caught. Timber decking on a 20-storey block is not available, whatever the visualisation shows.

Spandrel panels, infill panels between windows and rainscreen backing boards all sit within the external wall build-up and all need checking against the classification, not against a marketing claim of fire resistance. Reaction to fire and fire resistance are different properties measured by different tests, and product literature blurs them.

Solar shading, brise soleil and photovoltaic panels fixed to the wall come with the same restriction. Where the design relies on external shading for overheating performance, check the classification before the overheating strategy depends on it.

And check the fixings and supporting steelwork as a system rather than product by product. A compliant panel hung on a bracket assembly that has never been tested in that configuration will fail at the point where someone asks for third-party evidence, which on a higher-risk building is now a routine question rather than an exceptional one.

Describing materials in the planning submission

The Design and Access Statement should describe the external envelope in terms that can survive the compliance check. Name the material, the finish, the colour reference and, for a relevant building, the reaction to fire classification you are relying on.

Avoid words that promise an appearance you cannot deliver. Timber-effect aluminium is honest. Timber cladding, on a drawing for a 20-storey block, is a commitment you will have to unpick later.

Where a fire statement is required at Gateway One, the external wall build-up is one of the matters it addresses. That document sits under Article 9A of the Development Management Procedure Order 2015 and the Building Safety Act 2022 framework, and it must be prepared by someone with the necessary fire-engineering competence. A Fire Statement is a report type where a competent professional is legally required, and an AI-assisted draft is a starting point for that person rather than a substitute for them.

Conditions, samples and later substitution

Most permissions carry a materials condition requiring samples or a sample panel to be approved before the relevant work starts. Read the wording. A condition requiring approval of samples of all external materials, discharged with a panel that does not match the regulation 7 specification, creates a conflict between the planning approval and the building control position.

The sequence that works is straightforward.

1. Fix the reaction to fire specification with the fire engineer before the materials schedule is issued.
2. Submit that specification with the application, so the condition is drafted around materials that can be built.
3. Discharge the condition with samples of the specified products, naming classifications.
4. Record the approval and the correspondence in the project file.

Substitution after approval is where breaches occur. Swapping a product for a visually similar one changes the approved plans, and if the change is more than trivial it needs a non-material amendment under section 96A or a section 73 application. A substitution that also changes the fire classification is a building control matter as well, and the two approvals have to move together.

Heritage buildings and conservation areas

Conservation area policy pushes towards traditional materials, and traditional materials are frequently combustible. The conflict is real but narrower than it looks, because most listed buildings and conservation area buildings fall below 18 m and outside regulation 7(2).

Where a tall building sits in a sensitive setting, the resolution is usually a non-combustible product with a traditional appearance, agreed through a sample panel viewed on site rather than through a specification argued on paper. Bring the conservation officer to the panel. An officer who has seen the material in daylight next to the neighbouring terrace is far more likely to accept it than one reading a datasheet.

For timber structures the question shifts from cladding to frame, and the position on mass timber frames at planning stage covers the insurance and warranty issues that arrive alongside. Roof-level equipment raises its own version of the same problem, set out in the note on roof-level plant and photovoltaics.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it.

Draft the planning documents for a tall residential scheme on PlanScope, then send the fire statement to a competent fire engineer for review.

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