Soft Wash Across the UK

Soft washing is a low-pressure exterior cleaning method. A solution containing a biocide and a surfactant is applied at low pressure, left to kill algae, mould, lichen and bacteria, then rinsed off. It cleans by killing the growth rather than blasting it off, which makes it safer for delicate surfaces and keeps them clean for longer.

For render, roofs, painted surfaces, cladding and soft brick or stone, usually yes. High pressure can erode render and stone, wash out pointing, strip paint, break tiles and force water into walls and roof voids, and it often leaves spores behind so growth returns quickly. Pressure washing still has its place on hard surfaces such as concrete driveways and block paving.

Most soft wash solutions are based on sodium hypochlorite, the active ingredient in bleach, diluted to a strength that suits the surface, with a surfactant to help it cling. Some jobs use quaternary ammonium biocides instead, which work more slowly over days or weeks and are often used on roofs and delicate stone. The solution is matched to the surface and the type of staining.

It is when it is done properly. Plants are wetted before and rinsed after so they absorb less solution, delicate planting is covered, and run-off is diluted and directed away from beds and ponds. Pets should be kept indoors while the work is going on and until surfaces have been rinsed and dried.

Typically several years, depending on the surface, how shaded and damp the wall or roof is, and how close trees are. North-facing walls and roofs under trees tend to green up sooner. A light maintenance treatment every year or two keeps the surface looking clean.

Most algae and mould disappear during the clean. Lichen and some deeper staining can take days or weeks to fade fully as the biocide continues working and rain washes away the dead growth. Rust, paint and some mineral stains are not organic, so they need a different treatment.

Not when the solution is used at the right strength and windows, frames and painted surfaces are rinsed down. We pre-wet and rinse sensitive surfaces and protect areas that could be marked.

Not usually, as long as we have access to all sides of the property and an outside tap, and windows and doors are kept shut while we work. We will let you know when the job is finished.