Mould stains on walls are a sign of moisture problems in your home. If left untreated, they can spread and damage both your walls and your indoor air quality.
Here’s what causes mould stains, how to remove them, and how to stop them from coming back.
What causes mould stains on walls?
Mould stains appear when moisture builds up on your walls. They’re often a sign of damp or poor ventilation in your home.
Common causes include:
- Condensation from poor ventilation
- Water leaks or damp coming from outside
- Rising damp from the ground
How to spot mould problems in your home
Before removing mould, it’s important to understand what’s causing it.
Look out for these common signs:
- Musty smells in rooms
- Peeling paint or wallpaper
- Damp or cold patches on walls
- White powdery marks on surfaces
Identifying the cause is the first step to fixing the problem properly and stopping it from coming back.
The 3 main types of damp
1. Condensation
The most common cause of mould stains, usually due to poor ventilation and high humidity.
What you can do:
- Improve ventilation in kitchens and bathrooms
- Use a dehumidifier if needed
- Avoid excess moisture indoors
2. Penetrating damp
Caused by water entering your home from outside, often through cracks or leaks.
What you can do:
- Fix external cracks or leaks
- Check gutters and downpipes
- Make sure water drains away from your home
3. Rising damp
Less common, but more serious. It’s caused by moisture rising from the ground into your walls.
What you can do:
- Check for signs near skirting boards
- Improve drainage around your home
- Consider professional treatment if it persists
If you’re unsure what type of damp you’re dealing with, a professional survey can help identify the cause and the right solution.
How to remove mould stains from walls (step by step)
You can remove mould stains from walls yourself, but it’s important to do it properly if you want to stop them coming back.
What You’ll Need:
- Gloves and a mask
- A mould removal spray or diluted bleach solution
- A soft brush or sponge
- A clean cloth and warm water
Steps to follow:
- Protect yourself: Wear gloves and a mask
- Prepare the area: Open windows and remove loose mould
- Apply the solution: Apply your cleaning solution and leave it for 10–15 minutes
- Clean the surface: Gently scrub and wipe clean
- Dry the area: Make sure the wall dries completely
Always test your cleaning solution on a small hidden area first.
How to stop mould stains from coming back
Once you’ve removed mould stains, preventing them from coming back is key.
- Improve ventilation
Open windows regularly and make sure extractor fans are working - Control moisture
Keep humidity levels low, especially in kitchens and bathrooms - Fix external issues
Repair leaks, cracks, and make sure water drains away from your home - Use protective products
Anti-mould paints can help in problem areas - Stay on top of maintenance
Check gutters, pipes, and ventilation regularly
If mould stains keep coming back, it may be a sign of a deeper damp problem.
A professional damp survey can help identify the cause and provide a long-term solution.