Tanking

The system must be one which is specifically formulated to provide a watertight barrier to interior walls and floors beneath ceramic tiling. Tanking based on rubberised bitumous compounds or asphaltic compositions is normally unsuitable. Surfaces should be dry, clean, sound and free from dust. Porous surfaces may need to be primed prior to application of the liquid applied tanking membrane. Partition walls and timber floors must be adequately ventilated from behind or below to prevent dry rot and should be sufficiently strong and rigid to support the tiling. Gaps or cracks greater than 1.5mm wide must first be filled with a suitable filler or sealant. Cracks and joints less than 1.5mm should be reinforced with a suitable tape or matting, bedded into the waterproof coating. In addition the following locations should be similarly reinforced; all internal and external corners of walls/partitions and their junctions with bases, upstands, columns etc; all pipe penetrations, drainage channels and outlets; junctions of different base/background materials.
The liquid applied waterproof coatings are usually applied by brush, roller or trowel at a thickness of up to 2mm. They may be applied over entire floor areas where appropriate and up the walls to full height where necessary, but more often to the lower sections of the walls. The waterproof tanking system forms a suitable background for tiling direct with either a suitable cementitious adhesive (e.g. C2 type) or dispersion adhesive (e.g. D2 type).