May 21, 2025
Painting over mould is ineffective. First address the cause, properly clean affected areas, ensure complete drying. Learn more here.
Painting over mould is like wrapping duct tape around a broken pipe. It might look fixed for a moment, but the reality is that those stubborn mould spores will eventually push right through fresh paint.
You'll likely find your new paint job starting to peel within months as the mould continues its growth underneath.
Mould and mildew are tiny fungi that thrive in moist environments and shy away from sunlight. They commonly manifest as black, grey, or brown spots on walls, particularly in areas prone to dampness. You might notice discoloration in bathrooms, laundries, and kitchens, or see patches developing on the shady side of your house.
If you're unsure whether you're dealing with mould, a quick test can help: carefully dab a small amount of household bleach on the affected spot. If the area lightens or the spot disappears, it's a strong indication that you're looking at mould.
This isn't just an aesthetic issue; mould can pose genuine health risks. Exposure to mould can lead to a variety of problems, including:
For individuals with asthma or weakened immune systems, the consequences can be more serious. Children and the elderly are also particularly vulnerable to the effects of mould. Even what might seem like minor, persistent colds can escalate in damp, mouldy homes.
Before you even consider picking up a paintbrush, it's crucial to address the underlying causes of the mould. These often include dampness and poor ventilation, especially prevalent in bathrooms and laundries. Water leaks from your roof, plumbing, or windows can also contribute significantly.
Condensation forming on cold surfaces during winter is another common culprit, as is rising damp, which is frequently seen in Sydney homes with sandstone foundations.
Finally, don't overlook poor drainage around the exterior of your building, as this can create the moist conditions mould loves.
Addressing mould effectively requires a methodical approach.
Before you begin, wear gloves, a quality dust mask or respirator, and protective eyewear. Cover up with long sleeves and pants to protect your skin. Ensure the area is well-ventilated by opening windows.
You have several effective options for cleaning mould. A bleach solution, made by mixing one part bleach with three parts water, is a common choice. Alternatively, you can apply straight white vinegar and let it sit for an hour.
A 3% hydrogen peroxide solution, left for 10-15 minutes, can also work. For a more natural approach, consider a tea tree oil mix (1 teaspoon of oil in 1 cup of water) or a baking soda paste (made with water for scrubbing, or dissolved in water for spraying).
A detergent mix, combining dishwashing detergent with warm water, and perhaps some Oregano Oil and Thyme Oil, can also be effective. If you opt for a commercial fungicide, be sure to follow the product instructions carefully.
Use a firm brush on stubborn areas. Scrub thoroughly until all visible mould is gone. After scrubbing, rinse the area completely with clean water. For outdoor areas, a pressure washer can make this job easier.
Remember to use fresh cloths or sponges regularly to prevent cross-contamination. For particularly tough spots, a plastic scouring pad used with detergent can be helpful. Discard all cleaning materials once you're finished.
Allow the cleaned surface at least 48 hours to dry. A full week is even better. You can use fans or dehumidifiers to speed up the process. Ensure the surface is bone dry before applying your first layer of paint.
Once your surface is clean, dry, and, most importantly, the underlying moisture issue has been resolved, you can begin painting.
First, apply a mould-blocking primer. This will prevent mould from growing again. Choose a premium quality, mould-resistant paint specifically designed for wet areas.
For added protection, you might consider adding a mildewcide directly into your paint. Finally, apply two good coats of paint, ensuring you don't skimp on coverage for the best results.
When it comes to products, professionals often recommend starting with a premium grade oil-based sealer/undercoat as the first layer. For areas previously affected by mould, Dulux Precision mould and stain blocker primer is specifically designed for this purpose.
Consider using semi-gloss or gloss paints, as these finishes are harder for mould to penetrate and are also easier to clean. An external grade acrylic paint is a good choice for outdoor areas prone to mildew.
Preventing mould is key to a healthy home. Improve ventilation in wet areas by using exhaust fans. Promptly fix any leaks and address drainage issues. In naturally damp spaces, consider using dehumidifiers.
Regularly clean bathroom grout and seals. It's also a good practice to wash exterior painted surfaces yearly with a mild detergent. Pruning trees and plants around your home can allow more sunlight to reach the exterior walls and discourage mould growth.
Regularly check and clear gutters to prevent water buildup around your foundations. If you're in an area prone to rising damp, which is common in Sydney, consider installing moisture barriers.
Remember, a proper fix takes a bit more time and effort, but it will save you the headache of redoing the job in a few months. Your health and your home deserve better than a quick cover-up.
Need help with your mould problem? Our trusted tradies can assess, treat, and properly paint any mould-affected areas in your home.
Sometimes, a mould problem is too extensive or persistent for a DIY approach. It's advisable to call in professionals if:
Here's what SnapTradie can do for you:
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