New building movement feature
Today’s requirement for building facades to incorporate increased levels of building movement has been met by Kawneer with the launch of a curtain wall system that counters counter slab deflection.
The systems manufacturer enhanced its stick AA110 curtain wall system with a large movement joint that gives more than seven times the vertical movement allowance of its predecessor.
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 jas developed a solution for the AA110 curtain wall that will allow +/- 15mm at a mullion/mullion joint.
Conventional stick curtain walling is widely specified in the UK and offers a cost-effective facade solution, particularly on buildings that do not have a requirement for significant movement allowance.
“One of the main complexities in designing a facade is the accommodation of slab movement/deflection and, due to the extension of structural spans seen in contemporary building designs, slab deflection is increasing,” the company said. “This places additional demands on a facade design team to accommodate movement between slab and facade.”
By increasing the deflection allowance in the curtain walling to +/- 15mm, the beams used to support floor slabs can be reduced in size and in 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. A transom profile (which incorporates 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.
It 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 while the expansion joint was in compression, extension and in the neutral position.
Kawneer’s lead technical consultant Gary Ledger said: “Our new expansion joint gives architects ultimate design freedom by providing a traditional stick curtain wall system that gives exceptional performance in the area of building movement.”