If you’ve spotted mould on an internal wall or ceiling, the short answer is: no, you shouldn’t just paint over it. Painting straight over mould may hide the stain for a while, but it won’t fix the cause or stop the mould from coming back. In many Australian homes, mould is linked to humidity, roof leaks, plumbing issues, poor ventilation, or condensation on cold surfaces.
The good news is that if the affected area is small and the material is sound, you can often clean and treat it properly before repainting. If the mould keeps returning, or if there’s soft plaster, bubbling paint, or a smell you can’t shift, it’s time to get a qualified tradesperson involved.
Why You Shouldn’t Paint Straight Over Mould
Mould is a living fungus, and paint does not kill it by itself. Even mould-resistant paint is only one part of the solution. If you paint over active mould, moisture can stay trapped underneath, which allows the mould to continue growing and can cause the paint to peel, blister, or discolour again.
It’s also worth remembering that mould can affect indoor air quality. If anyone in the home has asthma, allergies, or breathing issues, take mould seriously and avoid disturbing large patches without protection.
How To Treat Mould Before Painting
Before you start, find and fix the moisture source first. If the mould is caused by a roof leak, overflowing gutter, failed shower seal, blocked subfloor ventilation, or plumbing leak, treating the surface alone will not solve the problem. Roofing, plumbing, and similar regulated work should be handled by a licensed professional where required.
Once the area is dry and the cause has been dealt with, you can clean the surface carefully.
Step 1: Protect yourself and the room
- Open windows and doors for ventilation.
- Wear gloves, a mask, and eye protection.
- Cover nearby furniture and flooring.
- Do not dry brush mould, as this can spread spores.
Step 2: Clean the affected area
For a small patch on a painted wall, a mould cleaner from Bunnings or Mitre 10 may be suitable if used according to the label. Some homeowners use diluted household bleach, but many surfaces are better treated with dedicated mould removal products recommended for Australian homes. Always test a small hidden area first, especially on painted plasterboard, timber trim, or older finishes.
Wipe the area gently with a damp cloth or sponge rather than scrubbing aggressively. If the mould has penetrated porous materials such as damaged plasterboard, insulation, or swollen timber, cleaning alone may not be enough and replacement may be needed.
Step 3: Let it dry completely
The surface must be fully dry before sealing or painting. In humid parts of Australia, that may mean using fans or a dehumidifier and waiting longer than expected. Painting over a damp wall can trap moisture and lead to more mould growth.
Step 4: Seal and prime if needed
Once clean and dry, apply a stain-blocking or mould-resistant primer suitable for the surface. Dulux, Taubmans, and British Paints all offer interior primers and paints designed to help with problem areas. A primer helps stop old stains from bleeding through and gives your topcoat a better chance of lasting.
What Paint Should You Use After Treatment?
After treating mould properly, use a quality interior paint that suits the room. In bathrooms, laundries, kitchens, and poorly ventilated areas, a mould-resistant or low-sheen washable finish is often a practical choice. In living areas, the best finish will depend on the wall condition and the look you want.
Here’s a simple comparison:
| Option | Best For | Notes |
|---|---|---|
| Mould-resistant interior paint | Humid rooms and areas prone to condensation | Helps slow future growth, but won’t fix leaks or poor ventilation |
| Stain-blocking primer | Discoloured walls after cleaning | Helps prevent stains from showing through the topcoat |
| Standard interior paint | Dry, well-ventilated rooms | Fine if the mould issue has been fully resolved |
If the wall substrate is damaged, products alone won’t be enough. Gyprock/CSR plasterboard, James Hardie lining products, or other replacement materials may be needed depending on the wall or ceiling system, and a professional plasterer or painter can advise.
When To Call a Professional
Call a professional painter, mould remediator, or building tradesperson if:
- the mould keeps returning after cleaning
- the affected area is large or spreading
- there is a musty smell through the room or house
- the plasterboard is soft, swollen, or crumbling
- there is suspected water ingress from the roof, bathroom, or plumbing
- you’re dealing with ceilings, high walls, or hard-to-reach spots
In some cases, a licensed roofer, plumber, or builder may need to inspect and repair the cause before any painting is done. For electrical fittings near mould or water damage, switch off the area if safe to do so and have a licensed electrician inspect it.
How To Help Prevent Mould Coming Back
Prevention is just as important as treatment. In Australian homes, especially during humid or wet seasons, these simple habits can make a big difference:
- Use exhaust fans in bathrooms, laundries, and kitchens.
- Keep furniture slightly away from external walls.
- Fix leaks quickly.
- Ventilate rooms regularly, especially after showers or cooking.
- Wipe condensation from windows and frames.
- Check roof, gutter, and flashing condition after heavy rain.
If your home has ongoing moisture issues, consider whether better ventilation, insulation, or exterior repairs are needed. The National Construction Code sets requirements for many building elements, and a qualified tradie can help identify the right fix for your home.
And if you’re comparing home-maintenance resources across the Tasman, our sister site Trade Directory NZ can also be handy for general trade information.
If you want the job done properly the first time, find a qualified local painter on Aussie Trade Directory and connect with local painters near you.