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 silicone sealant and damp patches may appear around outside of glass enclosure.
What are causes of these problems?
Grout is one of main culprits. Although ceramic tiles are totally waterproof 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 tiles. The degree to which it spreads will depend on level of moisture present.
Grout can also be a problem if shower wall has been built out of plywood. Plywood expands at a different rate to tiles and this can lead to grout cracking and letting in moisture.
If grout is used as a sealant between bottom of tiles and top surface of rim of 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 seal it indicates presence of moisture – usually trapped moisture behind seal. This could mean that 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 wall, rather than any problem with silicone itself.