Rendered walls are everywhere in Sydney, and so is the green-black mould that creeps across them on the shaded side of the house. It’s tempting to attack it with a pressure washer. On render, that’s how you end up with stripped paint and water damage.
Why render grows mould
Render is slightly porous and holds moisture, especially on southern and western walls that stay damp and get little sun. Add Sydney’s humidity and tree cover and you have ideal conditions for mould, algae and lichen. The growth feeds on the moisture and the fine organic film on the surface, and it spreads outward from there.
Why you can’t just blast it
High pressure on render forces water past the paint and into the substrate, blows out any hairline cracks, and strips the coating. You get a clean patch surrounded by damage, and because the pressure only removed the surface growth and not the spores, it returns within weeks — often worse, because the surface is now more porous.
The right way: kill it, don’t scatter it
Soft washing applies a treatment that kills the mould, algae and lichen at the root, then rinses at low pressure. The growth dies off and the wall stays intact. Because the spores are killed rather than spread, regrowth is much slower. The paint, the render and any cracks are left undisturbed.
Keeping it away
Cleaning is half the job; slowing the return is the other half. Improving airflow where you can, keeping plantings back off the wall, and periodic soft-wash maintenance all extend the result. A wall that’s been properly treated stays clean far longer than one that’s been blasted.
Get render cleaned properly
Our house washing soft-washes render and painted surfaces, and we also handle dedicated mould and moss removal. Request a fixed written quote — 24-hour turnaround, $20 million public liability.
