Black spots on bathroom grout and silicone are almost universal in Bloemfontein homes. The cause determines whether you need a window or a waterproofer.
What causes bathroom mould
Mould needs moisture, warmth and a food source. In bathrooms, the food source is the organic material in grout, silicone and caulking. The moisture source is what you need to identify - condensation from showering, or actual water ingress through failed waterproofing.
Signs it's a ventilation problem
If mould grows on the ceiling and upper walls after showering and the bathroom has no window or a non-functioning extractor, condensation is the cause. The fix is proper ventilation - an openable window or a correctly specified extractor fan ducted to outside. Removing the mould without fixing ventilation just means it comes back.
Signs it's a waterproofing problem
If mould and damp appear on the lower wall around the shower or bath surround, behind the toilet cistern, or at floor level regardless of ventilation, water is getting through failed grout, cracked tiles or failed silicone. This is a waterproofing failure, not a ventilation problem. Regrouting and re-siliconing are the first steps; if the problem persists, the waterproofing membrane behind the tiles has failed.
What to do
Clean existing mould with a diluted bleach solution and allow to dry completely. Improve ventilation if condensation is the cause. Re-grout and re-silicone if the surface sealing has cracked. If damp returns through walls or floors, have the waterproofing membrane assessed - a bathroom tiled without a membrane behind it will eventually leak to the room below.
Go deeper:
Damp Walls? Why Waterproofing Can't WaitFrequently Asked Questions
How do I know if my shower has a waterproofing membrane?
You cannot see it - it's behind the tiles. If your shower is in an older home and the tiles were laid without a written waterproofing specification, there may be no membrane. A damp patch on the ceiling below is the clearest evidence.
Can you re-silicone a shower without retiling?
Yes. If the tiles are in good condition, removing and replacing the silicone beads at all corners and junctions can resolve surface water ingress without retiling.
Need a hand with this?
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Waterproofing in Bloemfontein