Pressure washing was the most common way to clean building surfaces until the advent of the Softwashing industry. Unfortunately pressure washing is not the most effective way to clean most buildings. Masonry and brickwork can be left damaged by pressure washing. And porous surfaces can crack and leak after pressure washing. This means that common substates, such as sandstone, brick, and render, cannot be cleaned adequately with a pressure washer.
There are some instances however when a pressure washer is preferable to softwashing. Durable non-porous substances, such as concrete, can be pressure washed. If organic growth and stains, typically red or green algae, and black mould, are present then they must also be softwashed, in order for the clean to be effective.
Tarmac- Pressure Washing
Concrete- Pressure Washing