Why You Shouldn't Just Paint Over Mould
By Ruth MacEachern
Product Manager
Nov 12, 2024
Mould is a common household issue that can cause significant damage to your home and lead to health problems for your family if not addressed quickly. One of the biggest mistakes homeowners make when they discover mould is to simply paint over it in the hopes that this will stop the problem from getting worse. While this might seem like a quick fix, it doesn't address the root of the problem and can lead to more severe issues down the line. If you find mould in your home, here's what you should do instead of just painting over it.
Where does mould come from?
Mould is a living, growing organism that spreads from microscopic spores that are carried on the air. When the dormant mould spores arrive in a damp and warm environment, they activate and start to grow. Mould starts to grow below the surface, spreading out tiny filaments that eventually break through onto the surface of the wall as dark patches. These black or dark green patches are the fruiting body of the mould colony from where more mould spores are released to expand the colony.
The damp conditions that mould thrives in are commonly caused by condensation on walls. The droplets of water on a porous surface will saturate the underlying material to cause a damp patch where mould can get a foothold.
Don’t paint over mould
While painting over a patch of mould on your will briefly hide the dark patches, the underlying structure – the mycelium – is unaffected, and will rapidly break through the new surface to create a new fruiting body. Painting over mould doesn’t kill the mould colony, and it won’t stop it from coming back again.
Instead of painting over mould, you need to first clean the material away and then remove the sources of moisture that allow the problem to come back.
The easy way to clean mould
Mould spores can be an allergen for many people, but there are some species which release chemicals called mycotoxins that can affect your nervous system and cause serious medical issues. If you are particularly allergic to mould or worried that you have an infestation of toxic black mould (such as Stachybotrys Chartarum), then you should have it professionally removed rather than put yourself at risk.
When cleaning mould you should wear eye protection, gloves, and a face mask to prevent unnecessary exposure to the spores. The most effective cleaning products for mould contain bleach, and it’s a good idea to wear old clothes as they may be damaged.
You can find fungicidal sprays in most supermarkets that are designed to kill mould, but it’s also possible to use dilute bleach – simply mix household bleach in a 6:1 ratio with water.
Spray the cleaning liquid onto the surface and then leave it in place for a minute or so to give it time to kill the mould. Once the mould on the surface is dead, you can simply wipe it away.
After you have removed the mould patches, dispose of any cloths you have used in the bin to prevent the mould from spreading elsewhere in your home.
How to stop mould coming back
The most common source of the moisture that allows mould to grow is condensation. Condensation is caused by water vapour being released from the air when it contacts a cold surface such as a wall or window.
Some water vapour is always present in the air of our homes. Activities such as bathing, cooking, and washing clothes will all release some moisture into the atmosphere, but when humidity gets too high, condensation is the inevitable result.
There are some steps you can take to reduce the amount of water vapour these activities release including ensuring that you use lids when cooking and avoid opening the dishwasher until it has fully cooled, but the most effective change you can make is to improve your ventilation.
Extractor fans such as the Cyclone 8 should be fitted in your bathroom and kitchen. Modern extractor fans feature humidity sensors that automatically activate the fan when humidity levels get too high. This removes the humid air quickly and stops it from building up.
When damp or mould are forming away from an obvious source of water vapour, whole house ventilation may be more effective. A ventilation specialist will be able to advise you about the best solution for your home.
Find out more
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