On a high-value property, the wrong method is not a cleaning problem. It is a repair bill.
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Or Call Us NowQuick answer. Match the method to the material: chemistry at low pressure for stucco, tile and shingle roofs, painted trim, wood and most stone, and force for concrete, pavers and dense masonry. On an architecturally detailed property the cost of getting that backwards is what makes it worth checking, because ornamental stone, aged stucco, clay tile and finished wood are both the easiest surfaces to damage and the most expensive to restore. Ask any crew what pressure and what dilution they plan to use on each surface before they start, and note that Valley Wash Pros is based in Fresno and works the Central Valley, so use this as the standard to hold a local operator to.
Soft washing cleans with chemistry at low pressure and belongs on stucco, tile and shingle roofs, painted trim, wood, and most stone. Pressure washing cleans with force and belongs on concrete, pavers, and dense masonry. On architecturally detailed homes the stakes are higher than usual, because the surfaces most likely to be damaged, ornamental stone, aged stucco, clay tile, and finished wood, are also the most expensive to restore.
The names sound like variations of the same thing. They are opposite approaches to the same goal.
Soft washing delivers water at roughly garden-hose pressure, typically under 500 PSI, carrying a surfactant and a diluted sodium hypochlorite solution. The cleaning is chemical. The solution clings to the surface, dwells for several minutes, kills algae, mildew, lichen, and bacteria at the root, and is then rinsed away. Because the substrate is never struck with force, nothing is eroded, chipped, or driven behind the cladding.
Pressure washing drives water through a narrow orifice at 2,000 to 4,000 PSI on commercial equipment. The cleaning is mechanical. No dwell time, no chemistry required. Dense materials that can absorb that impact, poured concrete, clay pavers, brick, and hardscape, come clean quickly and thoroughly.
The failure mode in each direction is instructive. Use pressure where you needed chemistry and you damage the surface while leaving the roots of the growth behind, so it returns in weeks. Use chemistry where you needed pressure and the embedded oil, rubber, and grit in a slab simply stay put.
When in doubt, the rule of thumb is simple: if the surface has a coating, a glaze, a finish, or a moisture barrier behind it, it wants soft washing.
Soft wash: stucco and plaster, painted or stained wood siding and trim, fiber cement, vinyl, clay and concrete roof tile, composition shingle, slate, wood decks and pergolas, awnings and canvas, and most porous natural stone including limestone, travertine, and sandstone.
Pressure wash: poured concrete driveways, walkways and pool decks, clay and concrete pavers, brick masonry, block walls, and heavy hardscape.
Depends, and needs eyes on it: flagstone and slate flatwork, aged mortar joints, cast stone ornament, decorative stamped and colored concrete, and any surface that has been sealed. Stamped concrete has a color hardener and sealer that high pressure will strip in a single pass. Aged mortar between stone or brick can be eroded out of the joint entirely, which turns a cleaning job into a repointing job.
Architecturally detailed homes carry a lot of surface that punishes a careless operator: carved or cast stone, ornamental ironwork, leaded and stained glass, wood corbels and shutters, tile inlays, and specialty finishes like lime wash or Venetian plaster. None of those should ever meet a high-pressure tip. On properties like that, the correct default is low pressure everywhere except the flatwork, with any exception decided surface by surface during the walk-through.
If you remember one thing from this article, make it this one.
Roofs should be soft washed. There is very little debate about it among people who do this work professionally.
The dark streaking that appears on tile and shingle roofs is largely Gloeocapsa magma, a cyanobacteria that feeds on limestone filler in roofing material. High pressure knocks the visible colony off but leaves the root structure and spores, so the streaks return within a season. Low-pressure chemistry kills the organism outright, and the result holds for years rather than months.
The damage side matters more. High pressure on composition shingle strips the granule layer that provides UV protection, which shortens roof life measurably. On clay and concrete tile it fractures the glaze and can crack tiles outright, and walking a tile roof incorrectly breaks more of them. Many roofing manufacturers specify low-pressure cleaning in their maintenance documentation, and a high-pressure wash can put warranty coverage at risk.
Our process for tile, shingle, and flat roofs is described on the roof cleaning page.
Nearly all exterior cleaning damage traces back to one of these.
1. One pressure setting for the whole property. A crew that arrives, sets the machine, and works from the roof to the driveway without changing anything is going to damage something. Material dictates settings, and settings should change several times over a full-property job.
2. Chemistry mixed too strong or left too long. Over-concentrated hypochlorite bleaches paint, discolors stone, and kills plants. Solution allowed to dry on a wall in direct sun leaves residue that is difficult to remove. Correct practice is a proper surfactant so a weaker mix can do the work, controlled dwell, and never letting the surface dry before the rinse.
3. No landscape protection. Beds should be saturated with clean water before any solution goes on the wall, and rinsed again afterward. Skipping that step is the most common source of post-job complaints, and on a property with mature specimen planting it is an expensive mistake.
4. Water driven behind the cladding. Spraying upward into siding laps, or high pressure at a hairline stucco crack or a gap around a window, pushes water into the wall assembly where it does not drain. The consequences show up as interior mildew weeks later, with no visible clue from outside.
Five questions that reveal whether an operator understands materials or just owns equipment.
A good operator answers all five without hesitating and will tell you plainly when a surface should be left alone or referred to a specialist.
Valley Wash Pros is a Fresno-based, family-run company. Our crews run daily throughout the Central Valley, and we are not going to pretend to be a Beverly Hills neighborhood outfit. We do take work outside our home region, and the honest way to handle it is for you to call and ask about your specific address rather than for us to imply a local presence we do not have. Details on scope and coverage are on our Beverly Hills page. Whether you hire us or someone else, the method guidance above holds regardless of who does the work.
Valley Wash Pros is licensed, insured, family-run, and available 24/7. We soft wash homes, roofs, and delicate surfaces and pressure wash the flatwork, changing method and settings by material rather than by job. Start with soft washing for walls and roofing, house washing for a full exterior, or pressure washing for driveways, patios, and masonry. Every job carries a 100% satisfaction guarantee.
Our home market is Fresno and the wider Central Valley, and coverage details for other areas including Beverly Hills are on the service area pages. Call (559) 975-8124 and describe the property. Ask about 10% off any service, plus an extra 5% for seniors, veterans, and essential workers.
Straight answers from the crew that does this work.
Yes, and on organic growth it outperforms pressure. Algae, mildew, lichen, and the biological film on shaded walls are living colonies, and chemistry kills them at the root while pressure only removes the visible part. The result is that a properly soft washed wall stays clean far longer than a pressure washed one. Where soft washing is not the right tool is embedded contamination in dense flatwork, such as oil, tire rubber, and compacted grit in a concrete driveway, which needs mechanical removal.
It can, and the more common problem is subtler than cracking. Stucco is a cement system applied over a moisture barrier and lath. High-pressure water finds hairline cracks, gaps at window and door trim, and utility penetrations, and forces water behind the finish where it cannot drain. Saturated framing and sheathing can grow mold inside the wall cavity with no exterior sign for weeks. Aggressive pressure can also pit and erode the finish coat itself, particularly on older or previously patched stucco.
On surfaces where biological growth is the problem, a soft wash typically holds noticeably longer because the organism is killed rather than knocked off. Roofs and shaded walls that have been properly soft washed generally stay clear for a year or more, with the exact interval depending on shade, tree cover, moisture, and airborne dust. Pressure washed concrete stays clean until traffic, weather, and organic debris rebuild, which varies widely by use. Neither method is permanent, and both benefit from being scheduled rather than deferred.
Most properties do. A typical full-exterior job soft washes the walls, roof, trim, and fascia and then pressure washes the driveway, walkways, and patio with a rotary surface cleaner. Having one crew handle both means the settings and chemistry change with the surface rather than the job being split between two contractors with a scheduling gap and divided accountability.
Handled properly, no. The solution is diluted well below the strength of undiluted household bleach, landscaping is saturated with clean water before any chemistry is applied so foliage absorbs very little, and everything is rinsed thoroughly afterward. Pets should be kept inside during the application and until surfaces have been rinsed and dried, the same as with routine lawn or garden treatments. Problems come from over-concentrated mixes, skipped pre-wetting, and solution left to dry in the sun.
More practical guidance from the Valley Wash Pros crew on exterior cleaning across Fresno and the Central Valley.
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