The single biggest cause of waterproofing failures is workmanship. Poor workmanship would account for 90% of all failures in waterproofing. The waterproofing membrane is only as good as the surface to which it is applied or installed. Builders have a large responsibility here.
Has the surface been constructed with falls for drainage?
Is the surface smooth and clean?
Is the surface free of formwork distortions, voids or protrusions?
Is the surface spoiled by previous trades debris and residues?
Has the surface been scrapped and vacuumed?
Every manufacturer specifies the surface conditions and preparation required for the application of their respective waterproofing membranes but Builders consistently fail to provide the optimum conditions for the performance of the waterproofing products.
Consistently there is insufficient time allowed in the conduct of waterproofing for the correct preparation before the application of the waterproofing membrane. Builders and Waterproofing Contractors are both at fault here. This is critical for the installation of the various ancillary and critical parts of the waterproofing.
This may include the correct installation of :
- waterstop angles,
- perimeter flashings,
- vertical flashing angles,
- pressure strip flashings,
- chased drop flashings,
- fillets and bond breakers at coves,
- control joints,
- drainage flanges,
- cavity flashing down turns,
- topping screeds for falls for drainage,
- reinforcing at junctions,
- overflow devices,
- linear strip drains and
- slip joints over suspended sheet flooring systems.
The detailing, preparation and installation of these critical parts of the waterproofing is invariably left to the last minute before the waterproofing is applied. Manufacturers
specify a bond breaker or sealant fillet at the junction of vertical and horizontal surfaces and these are generally also specified to be installed and / or cured before the installation of the waterproofing membrane.
The critical junction of the vertical and horizontal surfaces, were differential movement is most likely to occur, is a major cause of failures where poor detailing and inadequate cure of the bond breaker before membrane application adversely affects the membrane performance. There appears to be a consistent failure by both Builders and Waterproofing Contractors in allowing sufficient time for preparation and installation of critical ancillary parts to the waterproofing.
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