Soft Wash vs. Pressure Wash: Which Does Your Home Need?
Key takeaways
- Pressure washing uses high pressure to clean hard surfaces like concrete driveways, sidewalks and patios.
- Soft washing uses low pressure (under 100 PSI) plus a cleaning solution that kills mildew and algae. It is the right method for roofs, siding, brick, stucco and painted surfaces.
- Using high pressure on a roof or siding can strip shingle granules, force water behind siding, etch stucco and chip paint.
- Most homes need both: a soft wash for the house and roof, and pressure washing for the concrete.
What is pressure washing?
Pressure washing uses a machine that pumps water at high pressure, typically in the thousands of PSI, to blast dirt, grime and growth off a surface. On concrete, which is hard and porous, that force is exactly what you want. It pulls mildew, dirt and tire marks out of the pores and brings back the original color.
Professional crews use a rotary surface cleaner on flat concrete rather than a hand wand. The surface cleaner spins two jets under a hood at a fixed height, so the whole driveway gets the same treatment and you don't end up with light-and-dark stripes.
What is soft washing?
Soft washing uses low pressure, under 100 PSI, about what a garden hose puts out, combined with a cleaning solution made for the surface. Instead of knocking growth off with force, the solution kills the mildew, algae, moss and lichen at the root. Then everything is rinsed away gently.
Because the growth is killed rather than just sprayed off, a soft-washed surface stays clean longer. That matters in north Houston, where humidity and shade keep mildew and algae growing nearly year-round.
Which surfaces need which method?
- Soft wash: asphalt shingle roofs, vinyl and fiber-cement siding, stucco, brick, stone, painted wood, soffits and eaves.
- Pressure wash: concrete driveways, sidewalks, patios, pool decks, pavers and commercial lots.
- Either, depending on condition: fences and wood decks, which need lower pressure than concrete and careful technique.
Why you should never pressure wash a roof or siding
Asphalt shingles are covered in granules that protect them from the sun. High pressure strips those granules off and can lift shingle edges, which shortens the life of the roof. On siding, pressure can force water behind the panels and into the wall. On stucco it can etch the surface and leave permanent lap marks. On painted surfaces it can peel paint that was in good shape.
This is why the black streaks on Houston-area roofs should be soft washed, not blasted. See what causes black streaks on roofs for more on that.
How to tell what your home needs
A quick walk around the house usually answers it. Green or black growth on the shady side of the house, dark streaks on the roof, or a chalky film on vinyl call for a soft wash. A gray driveway, dark sidewalk or slick pool deck calls for pressure washing. Most homes in Spring, The Woodlands and Magnolia need both, so it's usually most efficient to do the house wash, roof cleaning and pressure washing in the same visit.
How often to do each
In the Houston climate, most homes do well with a soft wash every 12 to 18 months and a roof cleaning every two to three years. Driveways and sidewalks usually look their best with pressure washing every 12 to 18 months. Homes under heavy tree cover or near water tend to need everything more often.
Common questions
Is soft washing as effective as pressure washing?
For siding, roofs and stucco, it's more effective. Soft washing kills the mildew and algae instead of just knocking off the surface layer, so the surface stays clean longer and isn't damaged.
Can I pressure wash my own house?
You can, but it's easy to damage siding, stucco, paint and window seals with too much pressure, and spraying upward can force water into the walls. A low-pressure soft wash with the right solution is the safer way to clean a house.
Is soft washing safe for plants?
Plants are pre-rinsed before cleaning and rinsed again afterward so the solution doesn't sit on them.
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