Can you pressure wash render? (Short answer: no)
No. Acrylic render is a thin decorative skin, and a pressure washer etches it, drives water into the wall behind it and sprays mould spores across the surface instead of killing them. The right method is a soft wash — low pressure, the right chemistry — which starts at $300 for a Sydney home and leaves the render intact.
What high pressure actually does to render
Acrylic render is a decorative skin a few millimetres thick, sitting over blueboard, brick or blockwork. A pressure washer at cleaning distance hits that skin with force it was never engineered to take. It etches the surface, cuts lines into the texture and opens pinholes in the finish. Once the texture is cut, cleaning cannot bring it back — that wall is now a patch-and-repaint job, and matching an existing render texture is genuinely difficult.
The damage rarely shows while the wall is wet. It shows a week later, when the etched passes dry lighter than the rest and the wall wears faint stripes that track every sweep of the wand. Those stripes are permanent. The etched patches also hold dirt faster than the surrounding render, so the wall that was blasted clean in spring looks worse than its neighbours by autumn. High pressure is a fast clean with a long bill.
The water goes somewhere, and it is not off the wall
Render sheds rain arriving at atmospheric pressure. It was never asked to resist water arriving under high pressure, and it doesn't. Aim a pressure washer at hairline cracks, window heads, penetrations or joints and the water goes through them — behind the render, into the substrate. On modern acrylic-over-blueboard walls, that is your frame and insulation. On older cement render over brick, it is masonry that will hold the moisture for weeks.
Trapped moisture is how render goes drummy — the bond between render and wall breaks down, the surface sounds hollow when tapped, and sections eventually crack or let go entirely. Worth saying plainly: no cleaning method fixes drummy render. Not soft washing, not anything. That repair belongs to a rendering trade, at a rendering trade's prices. Which is exactly why the cleaning method should never be the thing that causes it.
Spores spread under pressure; the manufacturers say go gently
The green film and black streaking on rendered walls is alive — algae, mould, lichen. Blast it and you remove what you can see while spraying viable spores across the rest of the wall and into the fresh pinholes the pressure just opened. The growth comes back quickly, and it comes back patchy, because you have reseeded the surface while making it easier to colonise. That is the pressure-washing cycle: cleaner for a season, dirtier sooner.
The manufacturers have a view on this. James Hardie's maintenance bulletin for fibre-cement cladding — the board sitting under a large share of Sydney's acrylic render — specifies gentle washing, not high pressure. When the company that makes the substrate tells you to go easy on the bare board, the thin decorative coat over the top of it does not want more force. It wants less.
Soft washing: what it does, and what it honestly cannot
Soft washing runs at roughly garden-hose pressure and lets chemistry do the work. A surfactant lifts the dirt. A biocide kills the algae and mould at the root instead of relocating it. A controlled low-pressure rinse carries the lot off the wall. The texture is untouched, nothing is driven behind the render, and because the growth is dead rather than redistributed, the wall stays clean far longer than a blasted one.
Soft washing has limits, and we would rather name them. It will not fix cracked or drummy render, will not revive paint that has chalked through, and will not lift rust staining that has keyed into the finish — those are repair and repaint jobs. What it does is take a streaked, green, tired-looking wall back to clean without shortening the render's life. For most Sydney homes, that is the entire brief.
What a proper render wash costs
House soft washing starts at $300. Most single-storey washes land between $420 and $960 depending on wall area, and two storeys adds about 40% for the extra reach and rigging. Bundle the gutters or windows onto the same visit and the combined job comes down 5-15%. Those are not estimates that shift once someone is standing in your driveway — they are the prices the work is booked at.
If you want your exact number, the instant quote asks a few questions about the house and returns a firm, bookable price in about 60 seconds. It holds unless the place is materially different from what you described. No site visit to schedule, no waiting on a callback — just the figure, and a wall cleaned the way the people who make the wall actually want it cleaned.