Factsheets - Mould in bathrooms & showers

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Mould (mildew) in Bathrooms and Showers

Mould is a perennial problem in bathrooms and showers, as it is its perfect environment to grow and thrive.

Mould needs three things to grow:

• Moisture to enable germination.
• A food source – soap and dirt.
• Warmth to promote growth.

The reason that mould tends to grow on silicone sealant is because it is warmer than the surrounding tiles or ceramics.

Mould has two stages of attack

• Primary attack, which sits on the surface
• Secondary attack where the mould starts growing into the sealant, eating into it.

The sealants used on baths have “Mildew Resistance” which is limited and after a time the fungicide in the sealant is exhausted letting the mould grow and flourish.

There are proprietary fungicides (mould sprays) that can be bought in plumber's merchants and hardware stores to combat mould. They are essentially powerful bleaches and should be used with care (following the manufacturers instructions).

It is critical to keep surfaces where mould can grow clean. Wiping the surface regularly and applying mould spray when it is found means that the mould cannot go beyond the primary phase. This should assure that the mould is kept under control and does not destroy the sealant damaging or destroying the water seal.

This data was taken from technical advice from GSL Technical 024 764 66603 (the main support group for Dow Corning Sealants)