Fire safety of metal balconies and balustrades

At a glance

A2-s1,d0 reads: class A2, smoke production s1 (lowest), no flaming droplets d0. A1 is the highest class. Heights are measured as in Diagram D6 of the Approved Document.

The 11 m and 18 m lines

The two heights come from two different documents, and the difference matters. 18 m is the regulation. Regulation 7(2) of the Building Regulations 2010 applies to a “relevant building”: one with a storey at least 18 m above ground level that contains one or more dwellings, an institution, or a room for residential purposes. The Approved Document’s note says that includes student accommodation, care homes, sheltered housing, hospitals, boarding-school dormitories, hotels, hostels and boarding houses. Materials that become part of an external wall or a “specified attachment” must be class A2-s1,d0 or A1, other than those exempted by regulation 7(3). Balconies, solar panels and solar shading count as specified attachments.

11 m is guidance. For buildings with a residential purpose (purpose groups 1 and 2) with a storey 11 m or more in height, paragraph 10.10 (Volume 1) or 12.11 (Volume 2) says a balcony should either contain only class A1 or A2-s1,d0 materials, with a list of exceptions, or have an imperforate soffit across the whole balcony, of at least REI 30 and in A2-s1,d0 or better, with a band at least 300 mm wide of A2-s1,d0 or better centred on any compartment boundary that lower-class material crosses. Both volumes say that where regulation 7(2) applies, it prevails.

Below 11 m, the guidance sets no class for balconies but says to consider the choice and arrangement of materials of attachments such as balconies (para 10.4 in Volume 1, 12.4 in Volume 2); ask the fire engineer. The height is that of the top storey, measured from its upper floor surface to ground level on the lowest side of the building, excluding rooftop plant areas and any top storey consisting only of plant rooms (Diagram D6).

What counts as the balcony

Regulation 7(2) looks at materials, not at a product label. Every material that becomes part of the balcony is in scope unless regulation 7(3) exempts it: the frame, the posts, the rails, the infill, the soffit and any cladding. A handrail cap in another material is in scope. One exemption is for the top horizontal floor layer of a balcony, in class A1fl or A2fl-s1, provided the whole layer has an imperforate substrate under it. Fixings, seals, gaskets and sealants are exempt, and so are thermal breaks where the Part L thermal bridging requirement needs them.

Approved Document B separately prohibits relevant metal composite material, the sandwich of metal skins and a plastic core, in external walls and specified attachments of any building at any height (regulation 7(1A)). It defines it as a panel or sheet no more than 10 mm thick, of two or more layers of which at least two are metal, with a substantial layer (at least 1 mm thick or 1 kg/m²) of a material with a gross calorific value above 35 MJ/kg when tested to BS EN ISO 1716.

Metals, coatings and infill

The table goes part by part. The first column is the component; the second is what the Approved Document says in the text we read; the third is what to ask for. Where the document is silent, the table says so and does not guess.

One point cuts across the table. The Approved Document does not say that metals are class A1. It says that untested products cannot be classified, and that some products are classified without further testing under a European Commission list. A metal product that is coated, laminated or part of a composite is a different product from the bare metal. So for each balcony part, the question is not “is steel non-combustible?” but “what is the classification of this product as supplied, and is it within the field of application of the test?”

Evidence to ask for

• A classification report to BS EN 13501-1 for each product in scope, issued by a laboratory accredited for the test, stating the class (for example A2-s1,d0).
• The field of application. Approved Document B says a classification is valid only within the direct field of application, for example a product fixed to a substrate of the class it was tested on (Appendix B, B8). Small changes in fixing method, joints, dimensions or air gaps can change performance (B2). A report for a flat panel is not evidence for a different build-up.
• The classification of laminated glass interlayers, if the glass is not accepted as exempt by Building Control.
• Coating and finish data sheets for any powder coat or paint, and a written view from Building Control on whether the coating needs its own class.
• Substitution control. Certificates apply to the product as tested. Ask the partner workshop to confirm in writing that no component, coating or infill changes without approval.
• Where it goes. File the reports with the fire documents for the project; see the fire documentation matrix.

Existing buildings need care too. Where a change of use makes a building into one described in regulation 7(4), regulations 5(k) and 6(3) require the external walls and specified attachments to be investigated and, where necessary, upgraded (Vol 1 para 10.17; Vol 2 para 12.18). Guarding height and sphere rules are separate: see balustrade and handrail rules. Corrosion between dissimilar metals is in galvanic corrosion and dissimilar metals.

All materials of balcony [B1], including frame, posts, rails, handrail, infill, soffit and any cladding, are to be class A2-s1,d0 or A1 to BS EN 13501-1 in accordance with regulation 7(2) of the Building Regulations 2010, other than components exempted by regulation 7(3). The top horizontal floor layer may be class A1fl or A2fl-s1 over an imperforate substrate. A classification report for each product as supplied is to be issued before ordering.

Balconies at [level or height] on a building with a residential purpose and a storey [11 m or more] above ground level are to comply with Approved Document B Volume [1 / 2] paragraph [10.10 / 12.11], by route [(a) only class A1 or A2-s1,d0 materials with the listed exceptions / (b) imperforate soffit, REI [30] minimum, class A2-s1,d0 or better, with a [300] mm band at compartment boundaries]. Where regulation 7(2) applies it prevails.

No relevant metal composite material, as defined in regulation 2(6), is to be used in any external wall or specified attachment (regulation 7(1A)).

No substitution of any balcony component, coating, infill or interlayer without written approval from [fire engineer] and the building control body. Each classification report applies only to the product, substrate and fixing as tested. Reports to be filed in the fire documentation pack.

Standards and sources

• Approved Document B Volume 1 (dwellings) and Volume 2 (buildings other than dwellings), 2019 edition incorporating 2020, 2022, 2025 and 2026 amendments, for England: gov.uk page updated 16 Sep 2026; both PDFs read 7 Nov 2026.
• Building Regulations 2010, regulation 7: as printed in the Approved Document; the legislation was not read.
• BS EN 13501-1: classification standard named by regulation 7(2); a listing summary shows the 2018 edition current; not read.
• BS EN ISO 1716: named in the definition of metal composite material; not read.

Questions we are asked

Does the 11 m rule apply to every building?

No. In Approved Document B it is guidance for buildings that include a residential purpose (purpose groups 1 and 2) with a storey 11 m or more in height. The legal requirement is regulation 7(2) at 18 m, for relevant buildings.

What does non-combustible mean for a balustrade?

In regulation 7(2) the test is a European classification of A2-s1,d0 or A1 under BS EN 13501-1. Specify the class and ask for the evidence; do not rely on the word “non-combustible”.

Is a powder-coated steel balustrade acceptable above 18 m?

The text we read does not address coatings on balcony parts. Steel can be a candidate, but the question of whether the coating needs its own classification should go to Building Control, with a classification report for the coated product.

Is a glass balustrade exempt?

Regulation 7(3) exempts window frames and glass, and Approved Document B says that includes laminated glass in the external wall. It does not say in the text we read that this covers balustrade glass. Get the building control view in writing and ask for the interlayer’s classification.

Does it apply to hotels?

Yes. The Approved Document’s note to regulation 7(2) names hotels, hostels and boarding houses, and Volume 2 purpose group 2(b) is residential (other). The 18 m test is the height of a storey above ground level.

Can a timber handrail be used on a tall balcony?

Not unless its classification meets the requirement. Timber is not in the list of exemptions in regulation 7(3). Ask for a Euroclass report and refer the question to the fire engineer.