Mould returning to your walls after a fresh paint job is one of the most frustrating problems a homeowner can face. As a professional home painter in blue mountains and Western Sydney with over 30 years of experience, I can tell you that mould coming back after painting almost always means the root cause was never properly addressed before the brush touched the wall.
Why Does Painting Over Mould on Walls Not Work?
Painting directly over mould does not kill it. It temporarily covers it. Mould is a living organism that feeds on moisture within the wall substrate. A coat of paint on top simply traps it, and within weeks or months it pushes back through the new surface.
What Is Actually Causing the Mould to Grow?
Mould grows where moisture is present. The most common sources in residential homes include:
- Poor ventilation in bathrooms, kitchens and laundries
- Condensation building up on cold or poorly insulated walls
- Leaking pipes running behind wall cavities
- Rising damp travelling up from the foundation
- Inadequate waterproofing in wet areas
Until the moisture source is identified and fixed, no paint product will stop mould from returning. This applies to standard paint, anti-mould paint, and every product in between.
Does Anti-Mould Paint Actually Stop Mould Coming Back?
When property owners look into using anti-mould paint in sydney, it is important to know how these products work. They contain fungicide additives that slow down mould growth on the paint surface. It is a highly useful product in the right situation. However, it is not a substitute for treating the wall properly before painting.
If moisture is still present in the substrate, anti-mould paint will delay the problem rather than solve it. The mould will return, often within a single season.
How Should Mould on Walls Be Treated Before Repainting?
Proper mould treatment before repainting follows a clear process. The mould must be killed at the surface using an appropriate fungicidal solution, not just wiped away. The wall then needs time to dry out completely before any primer or paint is applied.
Skipping the drying stage is a very common mistake. A wall that looks dry on the surface can still carry significant moisture through its depth, particularly in older homes across the Blue Mountains and Hills District.
Why Do Blue Mountains and Western Sydney Homes Struggle with Mould?
The Blue Mountains climate is persistently humid, with high rainfall and limited drying conditions through winter. This creates ideal conditions for mould growth on both interior and exterior walls, particularly in older homes with limited insulation or ventilation. This is why working with a trusted home painter in Blue Mountains who understands local architectural challenges is so important.
In Western Sydney, the issue tends to be concentrated in bathrooms, laundries and south-facing rooms where condensation builds up during cooler months. Suburbs like Kellyville, Castle Hill and Baulkham Hills see this regularly in newer builds where airtight construction reduces natural airflow.
What Is the Right Way to Paint a Wall That Has Had Mould?
The correct process requires four steps that cannot be reordered or skipped.
- Fix the moisture source, whether that is a leak, ventilation problem or rising damp
- Kill and remove all visible mould using a fungicidal wash
- Allow the wall to dry thoroughly before applying any product
- Prime with a quality mould-resistant primer, then apply two coats of a suitable paint
Any painter who skips step one or step two is setting you up for the same problem within months.
When Should You Call a Professional Painter to Deal with Mould?
You should call a professional when mould has returned after a previous paint job, when it covers a large area, or when you cannot identify where the moisture is coming from. These situations require proper diagnosis, not just a fresh coat of paint.
If you are in Kellyville, Castle Hill, Baulkham Hills or anywhere across the region and want to book a professional home painter in Blue Mountains or Western Sydney, I am John from Decor8. I am a fully licensed, MPA-recognised painter with over 30 years of experience. I will identify what is driving the mould before recommending any painting work.
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