Kawneer introduces an enhanced expansion joint to accommodate building movement

In association with

Buildings.

Manchester’s Circle Square development is the first project to feature Kawneer’s AA®110 expansion joint

Today’s requirement for facades to incorporate increased levels of building movement has been met by Kawneer with the introduction of a curtain wall system that has superior capabilities for countering slab deflection. The company has launched a fully CWCT tested version of its AA®110 curtain wall system with an expansion joint that will allow for up to 15mm of building movement.

While a conventional pressure-plated and face-capped stick system curtain wall can be constructed with allowance for movement in the vertical direction, this is normally limited to +/- 2mm at a mullion/mullion joint. Kawneer has developed a solution for the AA®110 curtain wall that allows +/- 15mm at a mullion/mullion joint. Conventional stick curtain walling is widely specified in the UK and provides a cost-effective facade solution, particularly on buildings that do not have a requirement for significant movement allowance.

Kawneer AA®110 expansion joint

One of the main difficulties of facade design is accommodating slab movement, and – due to the use of ever-larger structural spans – slab deflection. This places additional demands on the facade design team to accommodate movement between slab and facade. When building designs require facades to withstand high slab deflections, one solution is to incorporate unitised curtain walling, like Kawneer’s AA®201 or AA®265 systems, which 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 walling is more readily used by most fabricators and installers in the UK, hence the development of the expansion joint by Kawneer. The standard mullion/mullion expansion joint only provides a +/- 2mm movement allowance. By increasing the deflection allowance in the curtain walling to +/- 15mm, the beams used to support floor slabs can be reduced in size and consequently in cost.

Working with our approved subcontractor FK Group, the first project to feature our AA®110 expansion joint is Manchester’s prestigious Circle Square Development. The 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. A unique transom profile (incorporating a concealed breather membrane) at each floor level provides allowance for the increased movement of the spandrel infill, while maintaining the air and weather tightness of the facade.

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 sufficient allowance for in-service building movement can range from a reduction in weather performance to glass breakage and significant system failure.

Buildings.

Expansion joint test

In order to prove the system and to ensure compliance with UK standards, the expansion joint has been rigorously tested during development to ensure 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 with the expansion joint in compression, extension and the neutral position. Kawneer’s expansion joint gives architects ultimate design freedom by providing a traditional stick curtain wall system that ensures exceptional performance in the area of building movement.

Help is at hand…and not just a Product Solution
Kawneer has also launched its Facade Workshop, which comprises a team of facade specialists set up to work collaboratively with developers, architects and engineers during the early stages of a project. The aim is to provide a unique design and consultancy service working across every aspect of the facade to ensure that the design intent and every detail is realised.

The thinking of the Kawneer team is early involvement always leads to a successful outcome for the project. Kawneer is committed to providing expert advice, not only to solve problems for clients in terms of building movement, but also to ensure that facade selection and key design issues are highlighted and resolved as early as possible. As stated, early engagement is the answer to reducing these incidents of facade/building conflicts, and with its no obligation Facade Workshop, the company is offering to help refine the design, ensure the scheme is ‘value engineered’ and can be built on site safely.

Contact Details
For further information please visit the Kawneer website or contact Gary Ledger, Technical Consultant at Kawneer on 07976 825009 or email gary.ledger@arconic.com.