Malcolm Dobson, technical director of Technal, gives his tips on what to look out for on site to ensure the perfect curtain walling installation
1 Check the track record of the fabricator and installer. Do they really want this project? Can they cope with the scale of the contract? Regardless of the quality of the system, if workmanship is poor, the curtain walling will fail.
2 Make sure the design drawings from the curtain walling supplier address all the relevant interfaces with the general contractor’s works – such as cladding, brickwork, roof, concrete sills, doorways and paving.
3 Once on site, ensure sufficient lines of supervision are in place at every stage until the curtain walling is signed off. Be aware that glazing systems can be damaged easily if not handled and stored correctly.
4 Make sure the installation is correct or the building’s thermal performance will be compromised. Flashings may have to be lapped, joints should be screwed correctly and the application of sealant may be required. Too many buildings fail air permeability tests because of poor design detailing and installation. Again, adequate supervision on site and regular inspections are vital.
5 When the curtain walling is assembled, check that the junctions between the transoms and mullions are correctly fabricated, sealed and installed. The joints in the frame can fail under testing or in adverse weather conditions if fabrication quality is poor, there is insufficient supervision of installation or the system itself is not fully approved and performance tested.
6 All internal joints must be sealed to ensure air penetration is not possible. If the system is not airtight, rainwater will be drawn through, causing leaks, damp and deterioration. Again, a certified, performance-tested system is key.
7 Remember that curtain walling is generally not loadbearing. Items such as brises-soleils and signage can be supported if they are designed to work with the system. Heavier items such as maintenance walkways generally need additional supports taken through the curtain walling to the structural steelwork behind.