Showers can be a problem area for many householders. Although it will look pristine when new, a shower cubicle or over bath shower area can start to deteriorate and look shabby after a few years of use. The grout used between ceramic tiles can start to discolour, black spots start to appear in the silicone sealant and damp patches may appear around the outside of the glass enclosure.
What are the causes of these problems?
Grout is one of the main culprits. Although the ceramic tiles are totally waterproof the same cannot be said for all types of grout – especially if it is not correctly applied. One small gap or pinhole can be enough to start letting in moisture, and once this occurs mould can take hold and start to spread behind the tiles. The degree to which it spreads will depend on the level of moisture present.
Grout can also be a problem if the shower wall has been built out of plywood. Plywood expands at a different rate to the tiles and this can lead to the grout cracking and letting in moisture.
If grout is used as a sealant between the bottom of the tiles and the top surface of the rim of the shower tray or bath, this can also cause problems. Acrylic baths or shower trays flex very slightly during use, whereas grout will not tolerate any movement, and so cracks instantly. Wooden joists and floorboards will also move slightly under load or due to expansion, which again can lead to grout cracking.
Silicone sealant should remain mould free in a well-ventilated shower area. If black spots start to grow in the seal it indicates the presence of moisture – usually trapped moisture behind the seal. This could mean that the silicone seal has lost adhesion to one or more surfaces due to high levels of movement or poor preparation prior to its application. It could also be a symptom of grout failure further up the wall, rather than any problem with the silicone itself.
Damp patches on the wall or floor outside a shower cubicle can be attributed to one of the above causes, leaking waste or supply pipes, or occasionally by excessive sealant inside the cubicle, causing water to well-up in side the frame itself.
So what are the solutions?
The solution will depend on the severity of the problem – and keep in mind that much of the damage may be hidden.
Ensure that the shower tray or bath is securely anchored in place and does not move when someone stands in it. If you have access to the underside check any supply and waste pipes for leaks.
Cut away old sealant with a sharp blade and replace with a high quality sanitary grade silicone sealant containing a fungicide. Try and avoid cheap sealant that has less fungicide and a lower silicone content.
Treat mouldy grout with a surface cleaner, initially, to see how deep rooted the problem is. If the problem returns, then you might need to think about raking out the old grout and applying new.
Alternatively you could do away with grout altogether and install shower wall panels in place of ceramic wall tiles.
Each shower wall panel slots into the next one using a tongue and groove system, eliminating the need for grout. These panels are totally waterproof and can be fitted to any surface – including the existing tiles.
