How To Get Rid Of Mould
The method we used to clear a badly mouldy wall with a dedicated mould spray and the photos to prove it worked.
The short answer
To get rid of mould on walls, ventilate the room, put on gloves and a mask, and spray a dedicated mould remover such as HG Mould Spray liberally over the affected area. Leave it for the time on the label, then wipe it off with a damp cloth, rinsing the cloth after every wipe. Repeat on heavy growth, then tackle the damp or condensation causing it.
Black mould is worth dealing with as soon as you spot it. The NHS explains the health risks of damp and mould, particularly for children, older people and anyone with breathing problems, and left alone it only spreads further across the wall.
Clearing it is a straightforward job with the right product. We tackled a badly affected wall in one of our properties using a dedicated mould remover, and this guide walks through exactly what we did, with photos at each stage.
What You'll Need To Remove Mould
- A dedicated mould remover spray
- A bristle brush or old toothbrush
- A cloth and a bucket of clean water
- Rubber gloves
- A protective mask
- Paper towels
Why We Use A Dedicated Mould Spray
Home-made mixes and general bathroom cleaners are tempting, but for proper results we'd always use a formula made for mould. On this job we used HG Mould Spray, which came out on top in our tests of the best mould removers for walls and ceilings. You'll see from the before and after photos further down how well it worked.
Different products suit different surfaces. Some are strongest on bathroom sealant and grout, while others are made for painted walls and ceilings, so check the label matches the job. Whichever you choose, they're simple to apply, and the bottle tells you how long to leave it, which for most mould sprays is between 15 and 30 minutes.
How To Get Rid Of Mould On Walls
1. Prepare The Room
Before any spraying starts, take out anything that's easy to move, especially clothes, bedding and soft furnishings that could catch the spray. Open all the windows, then close the door behind you so the fumes stay in that room rather than drifting through the house.
2. Spray The Mould Remover Liberally
Put your gloves and mask on before you pick up the bottle. Lay a few paper towels along the bottom of the wall to catch any drips so they don't land on the floor.
In the Short below, you can see us spraying the formula generously from about 10cm away. We covered the whole area in one go without stopping, so there was no need to keep going back into the room while it worked.
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3. Work The Formula In
Some mould sprays need agitating, and the label will say if yours does. Use a bristle brush or an old toothbrush to work the formula into the mould, paying attention to corners and textured patches where it's thickest.
4. Leave It To Work
Once it's on, leave the room and get some fresh air. The exact contact time is on the bottle, and most mould removers need 15 to 30 minutes. Don't be alarmed if the mould turns yellow as the minutes pass, as that's the formula breaking it down.
5. Wipe It Off And Let It Dry
When the time is up, wipe the residue away with a damp cloth. Rinse the cloth in clean water after every wipe, otherwise you'll just smear the dead mould and chemical across the rest of the wall. Leave the wall to dry with the windows still open.
6. Check The Wall And Repeat
Have a close look once the wall is dry. If any dark patches are left, run through the process again.
Our Before And After Mould Results
Watching the spray break the mould down is oddly satisfying. This wall was in a bad way, with the worst of it in the top right corner and a dark band running along the top where it meets the ceiling.
The next photo was taken around 30 seconds after spraying, with the formula already sitting on the mould.
After about five minutes, the black mould had started to turn yellow and brown as the spray broke it down.
By 15 minutes, most of the mould had gone. There was so much of it to begin with that we sprayed it a second time and gave it another 15 minutes.
The final photo shows the wall after the second round and a wipe down, and the difference is huge. All it needs now is wall filler for the screw holes left by the cupboards that used to hang there, followed by white emulsion, or an anti-mould paint if the room stays damp.
Removing Black Mould From Silicone Sealant
Silicone sealant around baths, showers and sinks is one of the most common places for black mould, and it's harder to shift because it grows into the surface. Many mould sprays work on sealant as well as walls, so start by spraying the sealant and leaving the formula to work.
If you don't have a mould spray to hand, a paste of white vinegar, bicarbonate of soda and water can lift lighter growth.
Once mould has rooted deep into the silicone, no spray will fully clear it. The sealant in the photo below was in poor condition, so we cut it out and resealed with a mould-resistant bathroom sealant containing fungicides. Our guide to removing old bathroom sealant covers getting the old bead out cleanly.
Stopping Mould Coming Back
Removing mould only treats the symptom. It grows where moisture sits, so the long-term fix is cutting down condensation and damp in the room, whether that's a bathroom, bedroom or kitchen.
Ventilation comes first. Open a window while you shower, cook or dry clothes indoors, and keep air moving between rooms. If a bathroom stays steamy long after a shower, a powerful bathroom extractor fan makes a big difference.
In a room that's damp most of the time, a dehumidifier is worth buying. We run one in a bedroom at home, and it helps keep dust down as well. The first time you empty the tank, you'll be surprised how much water it has pulled out of the air, and our pick of the best dehumidifiers covers models for different room sizes.
If mould keeps coming back despite good ventilation, look for a leak, rising damp or a cold spot in the wall, as those need fixing at the source.
Quick Questions And Answers
Does bleach kill black mould on walls?
Bleach can remove the surface staining of black mould on hard, non-porous surfaces, but it doesn't reach the roots in porous materials like plaster and painted walls, so the mould comes back. A dedicated mould remover is made to penetrate and kill the growth. Never mix bleach with other cleaners, as some combinations give off dangerous fumes.
Why does black mould keep coming back?
Black mould keeps coming back because the moisture causing it hasn't been dealt with. Condensation from showers, cooking and drying clothes indoors settles on cold walls, and mould grows wherever it stays damp. Improve ventilation with open windows or an extractor fan, use a dehumidifier, and check for leaks or damp in the wall itself.
Can you paint over mould?
No, you shouldn't paint over mould, as it grows back through the new paint. Kill and remove the mould first with a mould spray, let the wall dry fully, and seal any stains with a stain block if needed. Then use an anti-mould paint, which contains fungicides to help stop new growth in damp rooms.
How long does mould spray take to work?
Most mould sprays take 15 to 30 minutes to work, and the exact time is printed on the bottle. On our wall, the mould started turning yellow after about five minutes and most of it had cleared by 15 minutes. Heavy growth needed a second application and another 15 minutes before it was gone.
Do I really need a mask and gloves for a mould spray?
Yes, because mould sprays give off strong fumes and the mould itself isn't something you want on your skin or in your lungs. Get the gloves and mask on before you pick up the bottle, then open the windows and shut the door behind you so the fumes stay in that room. Leave the room while the spray does its work.
Is HG Mould Spray worth using over a general bathroom cleaner?
For mould, we'd always pick a formula made for it, and HG Mould Spray is the one we used on this wall. It came out on top in our tests of the best mould removers for walls and ceilings. General bathroom cleaners and home-made mixes are tempting, but they aren't designed for mould growth.
Why did the mould turn yellow while the spray was working?
The yellow colour means the formula is breaking the mould down, so there's no need to worry. On our wall the black growth started turning yellow and brown after about five minutes. Keep to the contact time on the bottle, then wipe the residue off with a damp cloth and rinse the cloth after every wipe.
Can I clean mouldy silicone sealant or should I replace it?
Light growth on sealant can be sprayed with a mould remover or lifted with a paste of white vinegar, bicarbonate of soda and water. Once the mould has rooted deep into the silicone, no spray will fully clear it. We cut out the badly affected bead in our photo and resealed with a mould-resistant bathroom sealant containing fungicides.
Richard has spent years renovating properties and turning them into rentals and Airbnbs. Like a lot of people he started out as a beginner, and these days there isn't much DIY he won't take on.