Mould on Walls in Singapore: Why It Keeps Coming Back and How to Fix It
Mould grows where moisture sits: bathrooms, kitchens, household shelters, behind wardrobes and around aircon units. To fix it for good, remove the moisture source (leaks, poor ventilation), kill and clean the mould, let the surface dry fully, then repaint with an anti-fungal primer and paint. Painting straight over mould only hides it for a few weeks.
Why mould is so common in Singapore homes
Singapore’s relative humidity is high all year, often 70% to 90%. Mould spores are everywhere and only need moisture, a surface and stillness to grow. Common causes at home:
- Poor ventilation in bathrooms without windows or exhaust fans
- Furniture against walls, especially wardrobes on external walls, where air can’t move
- Closed-up rooms like household shelters and storerooms
- Aircon condensation, from dripping trunking or cold spots
- Leaks from pipes, the flat above, window frames or external walls
- Drying laundry indoors without ventilation
Is it mould, or something else?
| What you see | Likely cause |
|---|---|
| Black or green spots, musty smell | Mould |
| Brown ring-shaped stain on ceiling | Water leak, possibly from above |
| Bubbling or peeling paint | Moisture behind the paint |
| White powdery crust | Efflorescence (salts from damp walls) |
Water stains and efflorescence mean water is getting in. Fix that first. See wall and ceiling repair.
How to remove mould from walls
- Protect yourself: gloves, a mask and good ventilation
- Use a mould remover or a diluted bleach solution on hard, painted surfaces. Never mix bleach with other cleaners, especially ammonia.
- Let it work for the time stated on the product, then wipe or gently scrub
- Rinse and dry thoroughly, using a fan or dehumidifier if needed
- Check the next week. If spots return quickly, the moisture problem hasn’t been solved.
For large areas, mould inside wall cavities, or anyone at home with asthma or allergies, get professional help.
Repainting: doing it properly
When the moisture source is fixed and the wall is dry, repaint like this:
- Scrape off loose or peeling paint
- Apply a fungicidal wash and let it dry
- Seal with an anti-fungal or stain-blocking primer
- Apply two coats of anti-mould paint, matt for ceilings and washable for walls
A bathroom ceiling treatment and repaint usually costs $80 to $180. A kitchen or full room costs $150 to $350. Our paint guide covers which products to look for.
How to stop mould coming back
- Run the bathroom exhaust fan during and 20 to 30 minutes after showers, or leave the window open
- Leave a gap of a few centimetres between wardrobes and walls
- Open household shelters and storerooms regularly, or use moisture absorbers
- Service your aircon regularly so trunking doesn’t drip
- Run a dehumidifier in problem rooms, aiming for humidity around 50% to 60%
- Fix leaks promptly. For ceiling leaks from the flat above, contact HDB or your condo management.
Moving out with mould?
Mould on the bathroom ceiling is one of the most common reasons for deposit deductions. A quick anti-fungal repaint before your end of tenancy cleaning usually costs less than the deduction.
FAQ
Can I just paint over mould?
No. Mould grows back through normal paint within weeks. Kill it, dry the surface, then use anti-fungal primer and paint.
Does anti-mould paint really work?
It slows mould growth significantly in humid rooms, but it can’t overcome an active leak or a room with no ventilation.
Is wall mould dangerous?
Mould can trigger allergies and breathing problems, especially for people with asthma. Deal with it promptly and get professional help for large areas.
Who pays for ceiling leaks from the flat above in HDB?
For inter-floor leaks, HDB has a process, and repair costs are usually shared between the upper and lower flat owners. Contact HDB for help.
