Is soft washing just pressure washing turned down?

No. Soft washing is a chemical process: a biocide solution applied at low pressure kills algae, moss and lichen at the root, and the dead growth rinses or weathers away. Turning a pressure washer down removes the risk of damage but also removes most of the cleaning power, which is why the chemical does the work instead.

Can block paving be soft washed instead of pressure washed?

It can, and a biocide-only treatment will kill the growth, but it will not lift compacted dirt and grime the way a rotary surface cleaner does. The best result on paving is pressure washing followed by a biocide treatment.

Will soft washing chemicals harm my plants or pets?

Handled properly, no. Crews pre-wet planting, apply carefully and rinse down, and the surfaces are safe once dry. Pets should be kept off treated areas until they have dried or been rinsed, and a professional will tell you exactly how long.

How do I know if my render was damaged by a previous pressure wash?

Look for pale patches or streaks where the coloured surface has been stripped, often in fan shapes around where a lance was worked. It cannot be cleaned back; options are specialist render restorer products or re-rendering the elevation.

Pressure washing vs soft washing: which does your surface need?

Pressure washing cleans hard surfaces like block paving and concrete with high-pressure water. Soft washing cleans delicate surfaces like render, roof tiles and decking with low-pressure biocide that kills growth at the root. Using high pressure on a soft-wash surface causes permanent damage; using soft washing everywhere is slower but never destructive.

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Last updated: August 2026.

Two different jobs that share a van

Pressure washing and soft washing get sold under the same word, "jet washing", but they are different processes aimed at different problems. Pressure washing is mechanical: water at 150 bar or more physically strips dirt, algae and loose material off a surface that can take it. Soft washing is chemical: a biocide solution applied at roughly garden-hose pressure soaks into the surface, kills the algae, moss, lichen and mould living there, and the dead growth then rinses or weathers away.

The distinction matters because the damage in this trade almost always flows one way: high-pressure equipment used on a surface that needed soft washing.

Surfaces that take pressure

Block paving, concrete, imprinted concrete and most natural stone setts clean superbly under pressure, ideally with a rotary surface cleaner rather than a bare lance, because the spinning bar cleans evenly at a fixed height and avoids the zebra striping a lance leaves. Tarmac takes reduced pressure, enough to lift algae but not enough to tear the binder. Even on these tough surfaces the water only removes what is on the surface that day; spores in the pores survive, which is why a biocide treatment after washing is what makes the result last.

Surfaces that pressure destroys

Render

Modern renders, k-render, monocouche, silicone and acrylic systems, have a thin coloured surface layer. High pressure strips it, leaving pale patchwork scarring that cannot be cleaned back and often can only be fixed by re-rendering the elevation. Painted masonry peels, and pebbledash loses its stones. On Teesside's newer estates at Wynyard and Ingleby Barwick, render soft washing is one of the most common jobs in the trade, and one of the most commonly quoted wrong.

Roof tiles

Concrete tiles, standard on the 1930s semis of Acklam, Linthorpe and Hartburn, carry a granular surface layer that protects them. High pressure strips it, and the roughened tile then holds more moisture and grows moss faster than before. Pressure also forces water up under the laps into the loft and voids most tile warranties. The correct method is manual moss removal followed by a biocide soft wash, which keeps killing regrowth for years.

Decking

A pressure lance tears the soft wood from between the growth rings, furring and ridging the boards. The roughened grain drinks water, rots faster and grows algae sooner. Decking wants low pressure, a wide fan jet and an algicide doing the work. Composite decking scars too, and most manufacturers warn against pressure washing explicitly.

Old brick and lime mortar

Period properties in Norton, Yarm and on the Hartlepool Headland have soft brick and lime mortar that high pressure erodes. Gentle soft washing brightens them without removing the surface of the building.

Why soft washing lasts longer

Pressure washing removes the visible growth but leaves the roots and spores in the pores of the surface, so in Teesside's damp climate the green film can be back within months. A biocide kills the organism itself and leaves a residual effect that keeps working after application. That is why a soft-washed roof stays clear for years while a scraped-only roof can be mossy again in two seasons, and why the biocide line in a quote is worth more than the washing line.

The one-question test

Before agreeing to any exterior cleaning, ask which method will be used on each surface, and why. A good contractor answers per surface, paving under pressure, render and roofs soft washed, decking gently, because that is the correct answer. A contractor with one answer for everything has one machine on the van, and your render will pay for it.