Pressure washing vs soft washing — which one does your surface need?

Pressure washing uses force. Water at 2,000 to 4,000 PSI physically blasts dirt off a surface. It works because the surface is harder than the dirt.

Soft washing uses chemistry. Low pressure — usually under 500 PSI, about what a garden hose does — carries a detergent that kills algae, mould and lichen at the root. Then it gets rinsed off.

One removes what is sitting on top. The other kills what is growing in.

Concrete driveways, paths and patios. Concrete is hard, porous and takes high pressure well.

Exposed aggregate, at reduced pressure so stones are not dislodged.

Brick paving and bluestone, with re-sanding afterwards.

Commercial car parks, loading docks and forecourts.

Roofs. All of them. Tile, terracotta, Colorbond — high pressure cracks ridge capping, dislodges tiles and strips coating.

Render and painted walls. Pressure erodes render texture and can blow patches off around cracks and expansion joints.

Weatherboard and timber. Pressure raises the grain and forces water behind boards.

Anything with mould or lichen, because pressure only removes the visible growth and leaves the spores to regrow within months.

Striping on concrete means a handheld wand at inconsistent height. It is very hard to fix — the only real remedy is a full even re-clean.

Furring or fuzzing on timber means pressure raised the grain.

Loose or missing ridge capping after a roof clean means someone used pressure they should not have.

Moss returning within twelve months of a roof clean means it was pressure washed, not soft washed. The spores were never killed.