Kawneer launches market-leading building movement feature
June 2021

Kawneer introduces an enhanced +/- 5mm expansion joint to its high-performance AA®110 SSG system.

One of the main complexities in designing a glazed façade is the accommodation of slab movement/deflection, and due to the extension of structural spans seen in contemporary building designs, slab deflection is increasing. This places additional demands on a façade design team to accommodate movement between slab and façade.

When building designs require glazed facades to withstand high slab deflections one solution is to incorporate unitised curtain wall systems like Kawneer’s AA®201 or AA®265 systems, which due to their construction, can provide greater movement allowance.

However, unitised curtain walling usually comes at a cost premium and is generally more appropriate for very large facades and where there might be issues of site access. Traditional stick curtain wall is more readily used by most fabricators and installers in the UK, hence the development of a new expansion joint by Kawneer.

This new development has now enabled Kawneer to offer an expansion joint for its AA®110 SSG system that can withstand a +/- 5mm amount of movement tolerance.

The recent launch of the capped variation of the expansion joint for Kawneer’s AA®110 curtain wall system, which allows a +/- 15mm building tolerance, has now been successfully followed by the SSG (Structurally Silicone Sealed) variant.

While a conventional SSG system would be limited in its movement capabilities due to the hidden clamping nature of the glass and toggle engagement requirements, the new Kawneer solution has re-designed glass clamping rails and a re-designed toggle system to allow for greater slab deflection and differential movement.

The addition of the SSG expansion joint allows increased flexibility in architectural specification where the clean lines of a silicone glazed façade are desired, but without compromising the requirement for reduced slab sizes and cost.

The new joint locates at each slab level and is therefore concealed by spandrel glass or
panels. Its specialised engineered foam seals expand and contract with the movement of the structure.

To ensure compliance with UK standards, the new enhancement has been rigorously tested during development to ensure high performance in all UK conditions. In consultation with the CWCT, an enhanced version of the ‘Standard for Systemised Building Envelope: Sequence B’ programme was developed. This included a series of performance tests while the new +/- 5mm SSG expansion joint was in its compression, extension and neutral positions.

Alongside the new expansion joint enhancement, Kawneer has also increased the glazing weight capacity of the AA®110 system which will bring it in line with the current AA®100 system, providing glass weight capability of up to 600kg. The introduction of a 36mm thermal break provides enhanced thermal performance and increased glass thickness capability up to 50mm.

Kawneer’s Technical Director Gary Ledger commented: “Glazing and cladding systems need to be designed to allow for building movement without compromising the performance or safety of the system. The consequences of failing to provide enough allowance for in-service building movement can range from a reduction in weather performance to glass breakage and significant system failure.

“Our new +/- 5mm SSG expansion joint is a welcome addition to our AA®110 product offer and follows on from the popular capped expansion joint launched in 2019. This subsequently gives architects ultimate design freedom by providing a traditional stick curtain wall system that gives exceptional performance and tolerance of building movement.”