Torchon Edge Butted 3 Layer Systems
Recently 3 layer edge butted torchon systems have been specified and installed in the local market. The European torchon manufacturers do not support this methodology of installation.
The first rule in torchon waterproofing is that the layers must be continuous and uninterrupted to guarantee water tightness. The overlap not only guarantees this but acts a bit like a shock absorber as the membrane sheets undergo tension created by the membrane warming up and cooling down in various temperature conditions. The manufacturers insist on side and end torchon sheet laps as part of their specification and the EN standards generally and wouldn’t warrant a system which isn’t installed as specified.
Specifiers need to be aware that if there are any issues with this system, a registered building surveyor or consultant could only find against the edge butted system.