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Waterproofing a Wet Area

This article has been provided by BAL

Given the summer we have had in the UK this year, staying dry has been a problem for everyone recently – but in the world of tiling, keeping things watertight has always been a major issue. Highlighted in our last issue as one of the five most common technical questions fielded by the Technical Advisory Service at BAL last year, the waterproofing of tiled surfaces in wet areas requires careful thought and preparation. David Wilson, head of technical services at BAL provides us with the guidelines.

The key thing to remember when undertaking tiling in an environment exposed to regular wetting, such as shower rooms or wet rooms, is that a waterproof tanking system is absolutely essential. Any tiled surface in a shower room that has not had the background prepared with a tanking system runs the risk of failure. Luckily, tanking systems are easy to find and easy to use, and products such as the BAL WP1 Tanking System provide a comprehensive, flexible and seamless waterproofing solution for interior walls and floors.

Protecting the Background

A Tanking system is designed to protect backgrounds, bases and underlying structures from water penetration. As such, the system incorporates a waterproof coating, polyester tape for reinforcement of corners and joints, polyester matting, where required, for floors, and a wall & floor primer. Most manufacturers have options for projects both large and small; BAL, for instance, has the WP1 Tanking System pack, coupled with the WP1 Shower Waterproofing Kit for the common smaller shower applications. BAL WP1 and other tanking systems are not intended as damp proofing membranes, or as systems to prevent damp penetrating from outside the building.

Application

When applying the tanking system, the first stage is to prime the background with a suitable primer such as BAL Prime APD and leave to dry. If you are tanking over an existing glazed surface, or low-porosity tile backer boards, first apply a skim coat of an appropriate adhesive such as BAL Mosaic-Fix to the surface and allow to dry before priming. The waterproof coating then needs to be used to apply the polyester tape  to areas particularly susceptible to water penetration, including:

- Internal and external corners of walls/partitions, including their junctions with bases and columns.

- Pipe penetrations

- Junctions of different base/background materials

- Cracks and joints in the background/base

Once the tape is in place the waterproof coating, such as BAL WP1 Coating, needs to be applied to all walls and floors in the environment. For heavy duty wet areas, such as communal showers or industrial wet process areas, or where vibration or deflection of the base is expected, reinforcement with polyester matting is required. The membrane must then be allowed to dry for a minimum of 24 hours before tiling work can begin.

Completion

Once the tanking system is in place and dry, tiling can begin as normal, taking care to select a water resistant tile adhesive for walls, e.g. a D2, such as BAL White Star, and an equivalent for floor tiles such as BAL Single Part Flexible. Correct selection of the right tile grouts are also essential, and using anti-bacterial products such as BAL Microflex Wall Grout for walls and BAL Microflex Wide Joint Grout for floors will prevent the growth of black mould in tile joints. For showers with multi heads/body jets, use BAL Easypoxy Grout.

We would also recommend using an anti-bacterial silicone sealant to finish corners and joints, maintaining a completely waterproof seal in these susceptible areas and again resisting the growth of unsightly black mould.

Once the respective drying times of the adhesives and grouts have been adhered to, the tiled installation should now be completely watertight and ready to use.