The short answer
Use pressure washing for hard, durable ground surfaces such as car parks, forecourts, loading yards and concrete walkways. Use softwashing for anything with a finish or coating that high pressure could damage: render, cladding, roofs and painted masonry. For brick, stone, graffiti and chewing gum, steam is usually best, and for glass and solar panels, pure water.
| Method | How it works | Best for |
|---|---|---|
| Pressure washing | High-pressure water, often heated | Car parks, forecourts, yards, concrete |
| Softwash | Low pressure plus a biodegradable biocide | Render, cladding, roofs, painted surfaces |
| DOFF steam | Superheated steam at low pressure | Brick, stone, heritage, graffiti, gum |
| Pure water | Purified water and soft brushes | Glazing, solar panels, cladding rinse |
What is pressure washing?
Pressure washing (or jet washing) uses a powerful stream of water to blast dirt from a surface. Hot-water machines and rotary surface cleaners make it fast and effective on concrete, tarmac and block paving, where the surface can take the force. It is the standard method for car parks, petrol forecourts, service yards and bin stores.
The downside is that the same force can erode render, strip coatings from cladding, force water behind panels and blow out mortar joints. It also removes algae from the surface without killing it, so growth returns quickly.
What is softwashing?
Softwashing applies a cleaning solution containing a biodegradable biocide at low pressure, leaves it to work, then rinses it away gently. The biocide kills algae, lichen and mould at the root rather than just removing what you can see, and it keeps working after the clean, so buildings stay cleaner for longer.
It is the recommended approach for silicone, K-Rend, monocouche, acrylic and painted render, composite and powder-coated cladding, and most roofs.
When to use steam or pure water instead
- Brick and stone: DOFF superheated steam lifts carbon, paint and growth without abrasion. For listed buildings, a test patch is normally agreed with the conservation officer first.
- Graffiti and chewing gum: hot steam combined with surface-specific removers.
- Glass and solar panels: purified water and soft brushes give a spot-free finish and protect coatings and warranties.
Don’t forget the wash water
Surface water drains often run straight to rivers. Contaminated run-off from cleaning can lead to enforcement from the Environment Agency or the water company, so a responsible contractor controls wash water and recovers it where needed.
Getting it right
Most buildings need more than one method: pressure washing for the car park, softwash for the render and pure water for the glass. Prestige FM surveys the site, recommends the right method for each surface and puts it in a written method statement. See our exterior cleaning services or book a free survey.
