The short answer:pressure washing uses high water pressure (often 1,500–4,000+ PSI) to mechanically blast dirt, grime and stains off durable surfaces like concrete, driveways and brick. Soft washing uses low pressure (under 500 PSI) with a specialized cleaning solution to chemically break down algae, mold and mildew on surfaces that high pressure would damage, like roofs, siding and fences. They're not competing methods — they solve different problems, and a serious wash business usually ends up offering both.
The actual difference
Pressure washing is a hammer: mechanical force does the work, and the results are immediate. Soft washing is a solvent: a precise, application-specific chemical mixture does the work at low pressure, and because it addresses the algae or mildew at the root instead of just blasting the surface clean, the results last much longer. That's also exactly why soft washing exists in the first place — roofs, siding and other delicate materials can't take the pressure a driveway can without getting damaged.
Pressure washing is for
- Concrete driveways and sidewalks
- Patios and parking lots
- Brick and other durable masonry
- Equipment and machinery
Soft washing is for
- Roofs
- House and building siding
- Fences and other delicate structures
- Crossover uses like tennis courts, where pressure washing would be too aggressive
How soft washing actually became an industry
We were contacted in the summer of 2004 by a customer in Boston who wanted an enclosed pressure washing trailer to clean buildings with. We built it, shipped it, and flew out to train him on the unit in person. We stayed in touch over the years, and around 2013 he told us about a weird new system he was using for cleaning buildings — one that involved bleach. It turned out he was one of the first people to ever tell us about soft washing.
From there we watched it take off. Before soft washing, pressure washing a building could be genuinely dangerous, and it wasn't especially effective on algae. Word ran down the Eastern Seaboard — first a customer in Myrtle Beach, SC, then Georgia, then Florida — not from any advertising, just word of mouth about a technology that actually worked. Today we get calls from all over the country from people wanting to start a soft wash business, and it's grown into an industry that may someday rival pressure washing in size.
You don't have to choose just one
Since 2014 we've built soft wash setups that integrate directly into an existing pressure washing system — one rig, both capabilities, instead of running two separate businesses. A lot of our customers run exactly this kind of hybrid, offering pressure washing, soft washing, and sometimes mobile vehicle wash from a single trailer.
DETRAILERS options for each
Pressure washing
- DBP Series — open-trailer pressure washing
- DEP Series — enclosed pressure washing
- Dynamo — compact hot-water pressure washing
Want both on one rig? That's exactly the kind of hybrid setup we talk through in our first conversation.
Common questions
What's the difference between soft washing and pressure washing?
Pressure washing uses high water pressure (often 1,500–4,000+ PSI) to mechanically blast dirt and grime off durable surfaces like concrete and brick. Soft washing uses low pressure (under 500 PSI) combined with a cleaning solution to chemically break down algae, mold and mildew on surfaces that high pressure would damage, like roofs and siding.
Can I use one rig for both soft washing and pressure washing?
Yes. Soft wash setups can be integrated into an existing pressure washing system, which is how DETRAILERS has been building hybrid rigs since 2014 — one trailer, both capabilities.
Is soft washing better than pressure washing for roofs and siding?
For roofs, siding and other delicate surfaces, yes — soft washing is the safer and more effective choice. High pressure can strip shingle granules, force water under siding, and damage the surface. Soft washing's chemical solution kills algae and mildew at the root, which also means the results last longer than a pressure wash alone.