Winter's starting - act now to prevent mould growth
The temperature is dropping and the rain is setting in: winter is definitely coming. The cold season is the worst time for mould growth, and by springtime many exterior stone surfaces can be covered with brown, black or green mould growth. However mould CAN be prevented, if you act now.
Mould can be a real eyesore on a stone or tile surface
Mouldy stone surfaces can be a real eyesore. Unfortunately on any textured surface (such as many natural stones) the winter combination of damp + airflow = mould. Mould spores land on these surfaces, and start to grow, resulting in brown, black or green marks depending on the type of mould.
Shouldn’t sealing stop mould?
It’s a common misconception that sealers prevent mould growth. A good-quality sealer will inhibit dirt penetration, which is definitely a contributing factor to mould, but cannot prevent mould itself. The reason is that mould doesn’t require dirt to grow – it requires texture to grow into, and a supply of water. As most sealers are designed to allow water vapour transfer, water can still enter a sealed surface and “feed” the mould.
Limiting mould – commonsense solutions
There are a few obvious ways to help limit mould growth, including:
- Limit the accumulation of build-up on the surface (such as leaves or dirt).
- Do not allow water to sit on the surface (ensure good drainage).
- Allow sun to reach the surface as often as possible (do not cover).
All of these steps will limit the mould that’s able to grow on your surface, but it’s likely that mould will still grow. There is only one way to actually prevent mould growth: use a biocide.
Biocide kills mould as it starts growing
A biocide is “a chemical that destroys life by poisoning”. Using a slow-release biocide on a textured surface such as natural stone will kill mould on contact: as the mould spores land on the surface and start to grow, they will absorb the biocide and die.
Not only does biocide prevent mould growth, it also kills any mould that may be growing on the surface. Embedded mould that has grown into the stone’s structure may be slightly more problematic to remove, but can still be achieved.
A relatively inexpensive biocide treatment over 2 days will prevent mould for a number of months, and should last right through the winter season.
