Black mould on rendered exterior walls is extremely common in QLD's humidity — and soft washing is the only safe cleaning method. High pressure damages new render and voids manufacturer warranties.
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Black mould on rendered exterior walls is one of the most visible and common exterior cleaning problems in South East Queensland, particularly on the newer acrylic render finishes that have become standard on homes built across Redlands, Ipswich, Logan, the Gold Coast and the Sunshine Coast in the last two decades. Queensland's subtropical humidity, particularly in summer, creates near-perfect conditions for mould and algae to establish on render surfaces — typically appearing first on south-facing or shaded walls and spreading from there. The important thing to understand about render cleaning is that it requires a genuinely gentle approach — high-pressure washing on acrylic render can lift the surface coat, cause cracking and void manufacturer warranties. Soft washing is specifically the correct and only appropriate method for cleaned rendered homes.
Acrylic render has a slightly textured surface that provides excellent grip for airborne mould spores. Combined with Queensland's humidity and rainfall, the surface stays moist enough for mould to establish and spread quickly. Shaded walls, south-facing aspects and walls close to garden beds or fencing are typically the first to show mould growth.
New acrylic render surfaces should never be pressure washed. The force of high-pressure water can lift the surface coat, cause delamination and create cracks in the render surface that allow moisture penetration. On newly rendered homes this typically voids the applicator's warranty. Even on older render, the wrong approach can cause damage that's expensive to repair.
The SEQ housing boom has created thousands of newly rendered homes across Redlands, Ipswich, Logan and the Gold Coast growth corridors. New render that's less than 12 months old requires particularly careful treatment — we adjust our chemical concentration and dwell time to suit new surfaces and ensure zero risk of damage.
Soft wash results on render typically last 12 to 18 months. Shaded walls may need more frequent attention. Regular maintenance prevents the heavy mould build-up that makes cleaning harder and results in more visible staining over time.
No — pressure washing acrylic or cement render risks lifting the surface coat, causing cracking and voiding manufacturer warranties. Soft washing at low pressure is the correct method for all render types.
Queensland's subtropical humidity and frequent rainfall create ideal conditions for mould and algae growth on textured render surfaces. Shaded walls can develop noticeable growth within 6 to 12 months of a fresh render finish without regular maintenance.
Yes, but carefully. New render less than 12 months old requires adjusted chemical concentration and dwell time. We assess new render surfaces specifically and adjust our method to suit.
House washing with render cleaning starts from $499 for a standard property, including a free gutter clean. Final price depends on property size and extent of growth. Free quote before we start.
Serving Redlands and all of South East Queensland. We reply within 2 hours, Mon–Sat.
0412 291 614