Mould is a sign of a moisture problem
Black spots in the corner of a bedroom ceiling, grey patches behind a wardrobe or green speckles round a bathroom window all point to the same thing: moisture is sitting on that surface for long enough for mould to grow. Paint can cover the marks, but unless the moisture is dealt with, the mould will come back through or on top of the new coat. The first job is to work out where the water is coming from.
Condensation, penetrating damp and rising damp
Condensation is the most common cause in homes. Warm, moist air from cooking, showers, drying clothes and breathing meets a cold wall or window and turns back into water. It shows up on outside walls, in corners, behind furniture and around windows, and is often worse in winter.
Penetrating damp is water getting in from outside, through a faulty gutter, a cracked wall, failed pointing or a leaking roof. It tends to make a patch that grows after rain. Rising damp is moisture coming up from the ground into the base of walls. These are very different problems with very different fixes. We are decorators, not damp surveyors. If you are not sure which you have, a damp specialist or surveyor should diagnose it before any redecorating.
Cleaning and treating mould before painting
Once the cause is being dealt with, the mould itself has to be removed properly. Protect yourself with gloves, eye protection and a suitable mask, and keep the room ventilated. Avoid dry brushing, which spreads spores. Wipe the area with a fungicidal wash made for the job, following the instructions on the bottle, and leave it to work for the time recommended. Badly affected areas may need treating more than once. Mouldy wallpaper and silicone usually need to come off rather than being cleaned.
Let the wall dry completely before painting. Stubborn staining can be sealed with a stain-blocking primer so it does not show through the new finish.
What anti-mould paint can and cannot do
Paints sold as anti-mould or mould-resistant contain additives intended to discourage growth on the surface of the paint film. They can be a sensible choice in bathrooms, kitchens and other rooms prone to condensation. They do not fix the moisture that caused the mould in the first place, and they are not a substitute for treating the wall first. Think of them as one part of the solution, alongside ventilation and dealing with the cause.
Bathrooms and kitchens
These rooms produce the most moisture. A working extractor fan that is actually used, a window opened after showering or cooking, and lids on pans make a big difference. On the decorating side, washable finishes with a little sheen tend to cope better than flat matt paint, which can hold moisture and marks. Ceilings above showers are a common problem spot and benefit from proper preparation and a suitable paint.
Rented homes and between tenancies
Landlords and agents often see mould between tenancies, especially in flats with limited ventilation. A quick coat of white over it will usually reappear. Get the cause checked, clean and treat the affected areas, then redecorate with suitable paints. Giving new tenants simple advice on ventilation helps too. Our property maintenance page covers decorating for rentals.
Signs it might be more than condensation
Some clues suggest a problem beyond condensation: a damp patch with a tide-mark edge, staining that appears after heavy rain, white salts or powder on the wall, wallpaper lifting at skirting height, or plaster that feels soft. None of these is a diagnosis on its own, but each is a good reason to have a specialist look before decorating.
Reducing condensation day to day
Small habits make a real difference. Open trickle vents, use extractor fans while cooking and showering and leave them running afterwards, dry washing outside or in a ventilated room, keep a little background heat on in cold weather and leave a gap between furniture and outside walls. Wiping condensation off windows in the morning stops water collecting on sills and in corners.
Preparing the wall before the new paint
After cleaning and treatment, the wall still needs normal preparation. Loose or flaking paint is scraped back, cracks are filled and any stains are sealed. Silicone around baths and showers with mould inside usually needs cutting out and replacing. Only then is the finish applied.
Getting your walls redecorated
Once the moisture problem has been dealt with, we can clean, treat, prepare and repaint the affected rooms. Send photos of the walls and tell us what has been done about the cause. Call Eric on 07872 324935 or use the contact page.