Technical Specifications, Boundary Elevations Guidance

BCSA Technical Specification Boundary Elevations

On 1st July 2025, the British Constructional Steelwork Association’s (BCSA) Technical Specification for Boundary Elevations came into effect.

This guidance document for the construction industry highlights the latest design requirements for the primary frame, secondary steelwork and the external wall cladding, when used in boundary wall applications.

With new, strict responsibilities placed on Steelwork Contractors, Secondary Steelwork Manufacturers and Cladding System Manufacturers, this technical specification goes some way to ensuring the delivery of a competent boundary solution, but for many, this may also inadvertently restrict the design intent of future projects whilst giving rise to significant increases in both cost and the embodied carbon content associated with the structural frame and cladding system.

‘Capable Member’ Requirements

As per the Technical Specification for “boundary” elevations, there is a requirement for a capable member to be utilised at the head of the boundary elevation. Additional capable members will also be required below any structural openings or where breaks in liner continuity occur, such as interfaces between varying cladding system types.

Although capable members will most likely take the form of a hot-rolled section protected by an intumescent coating, this is not a prerequisite. A capable member can be hot rolled or cold rolled, providing the level of protection is adequate for the application.

As per the Technical Specification for “boundary” elevations, the specification of the capable member and its means of fire protection are to be determined by the steelwork contractor.

The frequency of further capable members must be determined on a project-specific basis by CA Group Technical Department.

There is no specific requirement for additional capable members at liner assembly end lap locations.

There is no specific requirement for external end laps (vertical cladding) to be located at the same position as the liner assembly end laps.

There is no specific requirement for additional capable members at changes in cladding orientation and/or external profile.

For the BCSA technical specification for boundary elevations paper, click here

Expert Guidance from CA Group

With over 40 years’ experience in the design, manufacture, testing and supply of independently certified building envelope systems, CA Group are expertly positioned to provide comprehensive guidance and advice on all cladding related topics and specification issues.

Our experienced team of in-house Technical Engineers are on hand to support architects, cladding contractors, principal contractors, clients & developers understand and deliver viable, market-leading solutions to these latest requirements, without sacrificing construction costs and carbon.

Updated guidance can be found in our new Technical Information Paper TIP-200 ‘Boundary Elevations’ accessible through our Resource Hub here.

If you have any questions or queries related to this matter, please don’t hesitate to contact CA Group Technical Department: technical@cagroup.co.uk.

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