Last checked 4 Nov 2026 against the sources at the end of this page.
Mould grows on a ceiling when the surface stays damp long enough for spores to take hold. In a Singapore flat that water usually comes from one of three places: shower steam, aircon condensation, or a leak from the flat above.
Work out which one you have before you scrub or repaint. Steam mould comes off with a cleaner and stays off once the room dries out properly. A leak has to be fixed first, because paint won't hold on a wet ceiling.
In short
- Mould right above the shower or around the exhaust fan is usually steam.
- If it runs along the aircon trunking, or sits on a brown-ringed stain under the flat above, wiping it won't keep it away.
- Repaint only after the ceiling has dried out and the mould has been killed, then finish with an anti-mould ceiling paint.
- In an HDB flat, a leak through the floor slab is a repair you share with your upstairs neighbour.
Steam, aircon or a leak: how to tell which one you have
Where the mould sits tells you most of the story.
| Where you see it | What it looks like | Most likely source | What to do first |
|---|---|---|---|
| Above the shower, in corners, around the exhaust fan | Black or grey dots spreading in a haze | Steam with nowhere to go | Clean it, then run the fan or open the window after every shower |
| Along the aircon trunking or around the indoor unit | A strip or ring, sometimes with drips | Condensation, or a leaking drain pipe | Get the aircon drain and insulation checked |
| A patch with a brown or yellow ring, under the upstairs toilet | A stain first, then mould, then bubbling paint | A leak through the floor slab | Talk to your upstairs neighbour before you paint |
| Top floor, grows after heavy rain | A damp patch that changes with the weather | The roof | Call your Town Council |
Steam is the usual cause. In a written answer to Parliament in February 2020, the Ministry of National Development (read 4 Nov 2026) said mould in HDB flats is usually caused by insufficient ventilation, since high humidity encourages it to grow.
Aircon water is the next suspect. HDB's aircon care guide (read 4 Nov 2026) tells owners to make sure condensation water isn't leaking and drains into a floor trap inside the flat.
A leak from upstairs behaves differently. HDB's ceiling leak guide (read 4 Nov 2026) says these leaks come through the concrete floor slab, usually from worn waterproofing in the toilet or bathroom above, and are common in older blocks. Left alone, HDB says, they can cause mould. If you're not sure, watch the patch for a week. Steam mould stays the same size and grows back where you wiped it, while a leak stain spreads outward, picks up a ring and darkens after the flat above has used its bathroom.
Can you clean ceiling mould off yourself?
Yes, if the patch is small, it's from steam and the paint underneath is still sound.
- Open the window and run the exhaust fan. Wear gloves and eye protection, as Dulux's bathroom painting guide (read 4 Nov 2026) advises when you use mould cleaners.
- Use a fungicidal mould cleaner or a dilute bleach solution, which is what that Dulux guide suggests, and follow the label.
- Give it time to work. If you plan to paint afterwards, Nippon's product pages say to leave its Anti-Fungus Solution on the patch for at least 2 hours.
- Wipe it down and let it dry. Dulux suggests cleaning the day before you paint, so the surface has time to dry properly.
Stand to the side of the patch rather than under it, so drips don't land on your face. Mould growing on a stain that's still spreading will be back within weeks however well you clean it, so find the water first.
Why you keep getting mould on the same ceiling
Usually the room still doesn't dry out between showers. Sometimes the water is coming from the aircon or from upstairs and never stops. And sometimes the last painter rolled fresh paint over live mould or damp plaster.
That last one catches people out. Nippon's Odour-less Anti-Mould Ceiling White page (read 4 Nov 2026) says the surface must have no water residue and a moisture reading below 4% before the paint goes on. Paint over a damp ceiling traps the water under the film, and the mould grows back through it. How anti-mould paint works, and what it can't fix, is in our anti-mould paint guide.
When to wipe the mould, and when to repaint the ceiling
Wipe it when the patch is small, the cause is steam, and the paint looks clean once the mould is gone.
Repaint when the mould returns within weeks of cleaning, the paint is bubbling or flaking, or a brown stain shows through after a leak repair. Do it in this order:
- Fix the water: the fan, the aircon drain, or the leak upstairs.
- Let the ceiling dry until a moisture meter reads below 4%, the figure Nippon gives for its ceiling paint.
- Scrape off loose and peeling paint, and fill hairline cracks.
- Kill the mould with an anti-fungus wash and leave it on for the time the label gives. Nippon's is at least 2 hours.
- Seal the ceiling. Nippon says its Vinilex 5170 Wall Sealer (read 4 Nov 2026) is anti-fungus and stops stain marks resurfacing on problem surfaces. Our sealer guide covers when a ceiling needs one.
- Finish with a paint made for damp rooms. Nippon makes its Anti-Mould Ceiling White for kitchens, bathrooms and the areas around aircons. Dulux recommends a specialty bathroom paint such as Dulux Mouldguard, which it says helps surfaces repel mould and stand up to steam and moisture.
If the ceiling shows rust lines or cracked concrete under the stain, that's spalling, and it gets repaired before any paint goes on. See our spalling concrete repair page.
Leak from the flat above: who pays and what to do first
In an HDB flat, HDB's ceiling leak guide says owners look after their own flats, floor and ceiling slabs included. When the slab between two flats needs repair, the two owners arrange the work and split the cost. HDB sets out the order:
- Talk to your upstairs neighbour about the leak and a possible cause, such as a choked pipe.
- Agree a time for a contractor to check and confirm the source.
- Engage the contractor together and agree on the repair method and cost.
- Pay the contractor once the work is done, with you and your neighbour each paying your agreed share.
On the top floor, the roof is common property, so contact your Town Council. HDB says the Town Council pays in full for repairs to the rooftop or an external wall.
If your flat is new, HDB's defects page (read 4 Nov 2026) says new flats have a 1-year defects liability period from key collection, and HDB follows up on items that need fixing in that time.
In a condo, tell the management office and the owner above in writing, with dated photos. Whoever does the leak repair, repaint the ceiling after it, not before.
When to call a painter instead of scrubbing again
Bring in a painter once you've cleaned the same patch two or three times and it's back again. A full repaint in the order above, after the water is fixed, takes less of your time than cleaning that patch every month.
It's the safer fix when the paint is flaking after a leak, when the ceiling is high or sits over a bathtub, or when you can see rust or cracked concrete. The same team plasters, repairs spalling and paints, so a damaged ceiling doesn't need three trades. On condo jobs we handle the MCST permits. We also record the paint brand, product, colour code and batch for your address, so a touch-up later matches.
Sources
- Ministry of National Development, written answer on mould on ceilings or walls of HDB flats, 3 Feb 2020, read 4 Nov 2026
- HDB, Preventing and fixing ceiling leaks in HDB flats, read 4 Nov 2026
- HDB, Maintaining air conditioners in HDB flats, read 4 Nov 2026
- HDB, Rectification of defects in new flats, read 4 Nov 2026
- Nippon Paint Singapore, Odour-less Anti-Mould Ceiling White product page, read 4 Nov 2026
- Nippon Paint Singapore, Vinilex 5170 Wall Sealer product page, read 4 Nov 2026
- Dulux Singapore, bathroom painting guide: mould removal and bathroom paint, read 4 Nov 2026