The key to long-lasting tiling
Last week we looked at the problems landlords have when the silicone leaks around the edge of baths and showers in rented properties. This week I’ll look at what to do if water has caused further damage to the walls, tiles are loose etc.
This is very common because people are still tiling onto plasterboard, which is totally unsuitable. Gypsum plaster is somewhat hydrophilic (it attracts and holds moisture) so using it in a shower is asking for trouble! Nowadays we have much better alternatives, specialist cement-based tile-backing boards such as Aquapanel and Hardiebacker. They are up to 12mm thick so can be used in place of plasterboard, or used over old lime-plaster walls. Hardiebacker can be cut with an ordinary saw, but a tungsten tipped one or a grinder is better. Aquapanel has a ‘skin’ of plastic fibres either side of a cement filling, so can be cut with a Stanley knife just like plasterboard. It needs to be fixed with 1½” number 8 screws, or 38mm plasterboard screws, every 150mm at the edges, 300mm in the middle. Joints can be sealed with good-quality silicone and taped, then tiled and the tiles sealed with silicone too. Belt and braces!
Using the correct adhesive is also important. Powder adhesive which needs mixing has the advantage that it sets by chemical reaction with water – it sets by wetting. It is ideal for use on wetroom floors, or on any surface which is frequently damp. Each subsequent wetting can only set it harder. Ready-mixed adhesive sets by drying. It is easy to apply but inclined to become soft again if left wet for extended periods. This is why your bathroom/ kitchen tiles in very damp areas fall off sometimes. Ready-mixed has an advantage over powder on very dry, porous surfaces, like new plaster or Hardiebacker (not Aquapanel), because powder adhesive may dry out too quickly to set properly. You can avoid this by spraying the backing board with water from an old Windolene bottle or similar. By the way, many professional tilers only use powder adhesive, mainly because it’s cheaper.
Even good-quality silicone will still need replacement occasionally, but if you follow these tips, you should never again have trouble with mildew and soggy boards beneath the tiles!
Next week I’ll look at why bathroom fixings like shower screens and loo roll holders frequently come adrift, and at making grouting easy by using the correct tools and materials.