A quick coat of freshly applied paint is, at best, a temporary solution for hiding mould. When painting over mould, there’s a process to follow to ensure you don't have to revisit the same spot in a few months. Get it right the first time, and a paint job should last for years.
The key to success lies in addressing the underlying cause of the mould, and the sooner, the better. Not only will it be better for your health, but it will be as easy as painting a wall. Here you'll find everything you need to know to achieve a good, long-lasting finish.
With over 20 years of experience in the building sector and years working for Build & Plumb Mark has developed a wealth of knowledge surrounding building and renovating that he enjoys sharing with others.
Tackle the cause of mould on walls first
To ensure that mould really doesn't return, you need to address the cause. There could be a number of reasons for the mould, as Mark Irving, building expert at Build & Plumb, points out, “Condensation is one of the most common reasons for the growth of mould on walls.”
He adds, “Warm moist air particles condense on cold surfaces, like walls, leaving water droplets and dampness. Damp walls are ideal environments for mould growth, as mould thrives on moisture.” Check out how to treat damp for more advice.
Typically, condensation occurs due to a lack of ventilation, but it's not the only factor, continues Irving, “Mould can also grow on walls due to unnoticed leaks from windows, pipes, roofs and so on.”
He adds, “Leaking water can soak into walls, causing dampness and creating the ideal conditions for mould growth, but this is typically a less common cause of mould than condensation.”
Try these to help get rid of mould before painting
If you need to get rid of black and brown mould, this cleaner is for you. It can be used in bathrooms, cleans silicone, and is safe for plaster. Comes with its own spray bottle.
A white anti-mould paint that is specially formulated to resist black mould and damp. Ideal for high-humidity areas like bathrooms and kitchens. Eco-friendly, it comes in a matt finish.
An all-round black mould remover that does a great job of removing and restoring a surface back to its best. Gentle on surfaces, no scrubbing needed, just wipe with a cloth.
How to treat mould before painting
Once the underlying issue has been addressed, the next step is to treat the mould. Specialist and home-made cleaners will get the job done. Jess Thomas, MD of Drainage Central, suggests a simple solution: “You will need to clean and treat the surface thoroughly. Use a fungicidal wash to clean mouldy surfaces, or create your own solution by mixing two parts bleach with ten parts water.”
Put the solution in a spray bottle and spray it onto the wall. Wipe with kitchen roll; use it only once, then throw it away. But be careful, as breathing in too many bleach fumes isn't good for your health. Make sure to wear a mask and rubber gloves.
Jess Thomas is an expert in the drainage and plumbing industry. Jess continually provides valuable insights on a wide range of industry topics and is dedicated to helping homeowners find effective solutions to their drainage problems.
Once the area is dry, it’s time to prep the surface. Jess Thomas says, “Prepare the wall by removing flaking paint with a scraper (like this DIY Doctor 4-Piece Wallpaper Scraper Set from Amazon), and brush the wall to remove any loose paint debris.” He adds, “Vacuum the wall to ensure that there are no flakes of old paint, as these will stick to the new paint and affect the finish.” Finally, use sandpaper to remove paint in hard-to-reach areas and improve paint adhesion.
With the surface ready, the next step is to seal it, Thomas says: “Use a primer or seal to cover any discolouration left by mould and to prevent damp from coming through in the future.” Irving adds, “A stain-killing primer is recommended for blocking water and mould stains.”
The final step is to paint the wall, Thomas says, “You can use an anti-mould paint or mix an anti-mould additive (like this Dryzone Anti-Mould Additive from Amazon) with other paint.”
How to paint over mould
Once you have cleaned off any mould and allowed the area to dry, remove any flakes of paints that may still be hanging around. You need a clean, dry, flake-free surface before you start.
1. Apply mould resistant paint
Start by applying your mould resistant paint (see below) with a brush. Make sure that you apply a good thick but even coat to cover the stains and leave to dry. If another coat is needed apply as before and let it dry as per the manufacturer's instructions.
2. Add a coat of oil-based paint
Once the mould resistant paint is fully dry apply a coat of oil-based paint like Dulux Trade White Undercoat or any oil based paint that you might already have with a brush and leave to dry. This helps create a water-resistant layer that will help even more to keep mould at bay.
3. Apply your top coat
Finally apply your top coat - typically emulsion - with a brush or roller. Ideally a roller will get a better more even finish. If putting up wallpaper, leave the wallpaper to dry out completely for 24 hours - then paint your walls or ceiling with your paint of choice.
Best anti-mould paint to use
Once you have eliminated the cause of the mould, given it a good clean, and let the area dry out, you need to find a good anti-mould paint to help prevent any mould reappearing. Polycell One Coat Damp Seal from Amazon and Zinsser Perma White Mould Resistant Paint from Amazon are good options. They resist moisture and steam and deter mould growth. They’re tough and washable but only available in white.
An alternative option is to purchase an anti-mould additive that you can mix in with your everyday paint to give mould-resistant capabilities. This Kair Anti-Mould Additive from Amazon is a good choice. One 50ml pot converts any 2.5 litre tin of emulsion or gloss into a mould-resistant paint. Great if you can’t find an anti-mould paint in the colour you want.
Mould can appear anywhere in the home, which means you might need to paint different areas. Check out our guides on painting a hallway, painting floorboards, and how to paint behind a radiator for pro pointers and tips to a great finish.
