Most homeowners think pressure washing is one thing. It's not. There are two fundamentally different methods, and picking the wrong one for the surface is the single biggest cause of homeowner pressure-washing damage.
The Two Methods
Pressure Washing
High-pressure water (1,500-4,000 PSI) blasts dirt and grime off hard surfaces. The pressure does the work. No chemistry needed for most jobs.
Right for: concrete, brick, stone pavers, unsealed pavers, fleet vehicles, fully cured stucco, commercial sidewalks.
Soft Wash
Low-pressure (under 500 PSI, often 100-200 PSI) application of cleaning chemistry — typically a sodium hypochlorite blend with surfactants. The chemistry kills mold, mildew, and algae at the root; the low-pressure rinse removes the dead organic material.
Right for: vinyl siding, wood siding, painted surfaces, asphalt shingles, stucco, screen enclosures, mobile home exteriors, cedar fences, composite decking.
Common Damage From Using the Wrong Method
- Pressure on vinyl siding: water forced behind the panels, causing mold growth in wall cavities and warped panels that pop off in the next storm
- Pressure on wood: raised grain, splintering, gouged surfaces that require sanding and refinishing to repair
- Pressure on shingles: blasted granules, shortened roof life, voided warranty (see our roof streaks article)
- Pressure on stucco: chipped surfaces and water intrusion that leads to interior wall damage
- Soft wash on heavy concrete stains: chemistry alone won't lift years of oil and tire marks — needs the mechanical pressure of a surface cleaner
The decision rule
If the surface holds water against itself (siding, shingles, wood) or has joints water can get behind, it's soft wash. If the surface is impermeable and structurally hard (concrete, brick), it's pressure wash.
How a Professional Decides
When we quote a job, we walk the property and assess each surface separately:
- Roof: always soft wash. No exceptions.
- Siding: soft wash for vinyl, wood, stucco, painted. Sometimes a brief pressure rinse for brick (still gentler than concrete pressure).
- Driveways, sidewalks, pool decks: pressure wash with a commercial surface cleaner attachment, then a chemical post-treat to kill any remaining biological growth.
- Decks and fences: soft wash to kill mildew, then low-pressure rinse. Never high-pressure on wood unless prepping for refinishing.
- Gutters and trim: soft wash on the exterior; mechanical clean-out on the interior.
What About DIY?
Rented pressure washers from box stores top out around 3,000 PSI with no chemical injection. They're fine for concrete. They are not safe for siding, roofs, or wood — and they don't have the soft-wash chemistry to kill organic growth at the root.
If you only have one surface to clean and it's concrete, a rental might be enough. If you have a house, roof, or any mix of surfaces, the time + risk + chemicals add up fast — and you don't have the right equipment for the soft-wash side.
The Cypress Pro Wash Approach
We bring both rigs to every residential job: a soft-wash system for the house and roof, and a high-pressure rig with surface cleaner for the concrete. Right method for each surface, in one visit. No second crew, no extra trip charge.