Choosing between soft washing and pressure washing is the single most important decision in any exterior clean — pick wrong and you can strip render, crack roof tiles or force water into your walls.
The short answer: pressure washing is for hard, robust ground surfaces like block paving and concrete, while soft washing is for everything delicate or biological — roofs, render, cladding and painted surfaces. Here's how to decide for your property.
What each method actually is
Pressure washing uses water at high pressure to physically blast dirt, algae and grime off hard surfaces. It's fast and effective on driveways, patios and paths that can take the force.
Soft washing uses low pressure — barely more than a garden hose — combined with specialist cleaning solutions such as biocides and surfactants. The chemistry does the work, killing moss, algae, lichen and mould at the root rather than just knocking the tops off.
When pressure washing is the right call
Block paving, concrete, stone flags and tarmac (at reduced pressure) all respond well to pressure washing. It removes surface grime, weeds and detritus quickly, and prepares paving for re-sanding and sealing.
Even here, technique matters: too much pressure or a badly-angled lance strips joint sand, etches soft stone and leaves stripe marks you can't undo.
When soft washing wins
Roof tiles, render (especially K-rend and monocouche), uPVC, painted surfaces and timber should almost never be pressure washed. High pressure drives water behind render, dislodges tile granules and voids many manufacturer warranties.
Soft washing cleans these surfaces safely, and because the biocide keeps working after application, results typically last considerably longer — regrowth is delayed for years rather than months.
Cost and longevity compared
Pressure washing is usually cheaper per visit, but on biological growth it's a shorter-term fix because spores survive and regrow. Soft washing costs more up front and typically stays cleaner for two to three times longer on roofs and render.
Many jobs use both: a driveway might be pressure washed then treated with a biocide, while the adjoining render is soft washed only.
Frequently asked questions
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