Protecting a water-sensitive substrate
Tiles are often specified for areas that are likely to be subjected to high humidity or become wet such as kitchens, bathrooms and showers. Whilst the tiles themselves are unaffected by water it is very difficult to ensure a complete seal at the grout joints. The tiling layer should not be considered to be a waterproofing layer.
1. Some tiling substrates are affected by water
Plaster will lose nearly all of its cohesive strength if it gets wet for any extended period.
Plasterboard has a paper face which also loses strength when wet.
2. Cement-based grouts are not impervious to water
3. Cement-based grouts are vulnerable to erosion and damaged over time
4. Movement cracks
Grout joints in corners between tiled surfaces and at junctions between dissimilar backgrounds should be filled with a flexible sealant to allow some movement between surfaces. These critical joints are often filled with the same grout used for the rest of the area. The grout will almost certainly crack in time allowing water through.
Using webersys protect tanking system
Water-sensitive substrates such as plywood, plaster and plasterboard can be protected from damage by any water that penetrates the tiling layer, by the application of a surface waterproofing layer, known as a tanking system. The most likely places for leaks are in internal corners and around pipes, plugholes, trim etc, so these areas must be treated with care.
Stage 1: Assess and prepare the surface
The surface must be clean, dry, sound and rigid. Existing surface layers (such as paint, tiles etc.) must be well adhered to a sound substrate. The surface to be coated must be free of wax and grease, and any dirt or dust must be washed off and allowed to dry. Prime the substrate with weber PR360 and allow to dry.
Stage 2: Protect critical areas with webersys protect tape
Apply webersys protect into the vertical and horizontal corners, into small cracks (less than 2mm wide) and along any joints between boards with a short-bristle brush. Apply it liberally to the base of any protruding pipes and over a square area within 100mm of the pipe. Cut a length of joint tape to fit and bed it into the webersys protect. Corners should be taped in all three directions to ensure a secure seal. For sealing around pipes, cut a cross in the tape with a knife.
Stages 3 & 4: Apply first & second coats of webersys protect
Stage 5: Fix the tiles
Leave webersys protect until dry, then fix tiles using a polymer-modified, cement-based adhesive such as weberset plus. A flexible adhesive will be needed on substrates with some movement.
Stage 6: Grout the tile joints
Allow the adhesive to fully dry, normally at least 24 hours (less for rapid adhesives) and then fill the joints with an appropriate grout. weberjoint pro offers increased resistance to water, soiling and limited movement. weberjoint epoxy is specified where chemical resistance or complete impermeability is required.
Fill the joints around the perimeter and in all horizontal and vertical internal corners with weberjoint silicone sealant to allow for movement. Allow the grout and sealant to fully cure before using the installation.
Solution with the following Weber products
Styrene acrylate dispersion for use with tile adhesives, levelling compounds and webersys protect
A ready-mixed, under-tile tanking system to protect water-sensitive substrates from exposure to water
A standard-setting non-slip tile adhesive for low-porosity tiles and substrates
A water-repellent, mould-resistant, flexible tile grout for interior and exterior use
Acetoxy curing silicone sealant that cures to form a tough, flexible, water tight seal – available in clear, white and a range of colours