The correct method depends on the surface, coating, access and type of contamination. Soft washing uses low-pressure application with an appropriate cleaning agent, followed by a gentle rinse. It is often suitable for painted facades, eaves, rendered finishes and areas where aggressive pressure could cause damage.
Pressure cleaning uses greater mechanical force and is generally reserved for sound, compatible hard surfaces such as concrete. Even then, nozzle choice, working distance and spray angle matter. Excessive pressure can etch concrete, scar timber, strip paint or force water behind cladding.
A professional clean may use both methods on one property. Pre-treatment can loosen organic growth, light agitation can address stubborn spots, and controlled rinsing removes residue. Test patches are useful on older paint, oxidised coatings and surfaces with an uncertain history. Oxidation, efflorescence, rust and permanent discolouration may improve, but they are not always removable through washing alone.