Soft washing is how exterior walls should be cleaned in Centennial: low pressure, the right solution, adequate dwell time, and a gentle rinse. It handles the organic growth and film that pressure cannot remove without damage — and on siding, painted surfaces, and stucco it is the only appropriate method.
Quick answer
Soft wash kills mildew, algae, and bacteria on exterior surfaces using low pressure (~500 PSI) and a biocidal cleaning solution.
The checklist is the same everywhere. What is on your glass is not. These are the conditions that actually shape this job in Centennial — each one is true here and false in plenty of other towns we serve.
Siding and painted surfaces have seams, laps, and fasteners. High pressure drives water past the surface into the assembly behind it, and it does not dry out from there. The result appears weeks or months later as blistering, staining, or a moisture problem that gets blamed on something else. Soft washing puts the work on the chemistry instead of the force, which cleans more thoroughly and leaves the wall intact. In Centennial this is not a preference, it is the correct method.
On nearly every Centennial property, the north and shaded elevations carry visible organic growth while the sunny sides look fine. Shade holds moisture, and moisture grows algae and mildew on any surface that will hold it. Pressure removes the visible layer and leaves the biology, so it returns fast. A soft wash with the correct solution kills the growth rather than just knocking it off, which is why the result lasts a season or two instead of a few months.
Centennial draws from Denver Basin aquifer wells blended with surface supply across several districts. Groundwater carries substantially more dissolved calcium and magnesium than a snowmelt supply, so every sprinkler pass, hose rinse, or cooler bleed that lands on glass leaves mineral behind when it evaporates. Homeowners who moved here from a soft-water Front Range city are routinely surprised how fast spotting appears — the house did not change, the water did.
Low-pressure (~500 PSI) wash of every exterior surface — vinyl, fiber-cement (Hardie), stucco, painted wood, brick, masonry. Hardware-friendly: trim, gutters, soffit, and fascia all included.
Biocide application — sodium hypochlorite-based solution (the standard for soft-wash) that kills mildew, algae, lichen, and the black/green biological staining you see on shaded north-facing walls.
Plant and lawn protection — surfactant rinse during application, then full rinse-down at the end so nothing carries to your landscape.
Window pre-coat — we coat windows with plain water before the biocide so any drift doesn't streak the glass. We can also include the windows in the same trip — soft wash + window cleaning is a popular combo.
Optional add-ons: deck soft-wash, fence soft-wash, full-property bundle with driveway pressure wash.
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Plant covers, lawn pre-rinse, window pre-coat (plain water). Pets indoors. We tape any wall outlets or vents that need protection.
Top-down soft-wash with the biocidal solution. Dwell time 5-15 minutes — long enough to kill the biological staining, not long enough to damage paint.
Plain-water rinse from top to bottom to remove all solution and dead biological material. We watch for any streaking and re-apply if needed.
Walk-around to confirm clean coverage, plants and lawn rinsed, no overspray on neighbors. Before/after photos emailed.
Most Centennial properties land between $325 and $730 for this service. That band is derived from real Centennial jobs, not a national average — which is why it differs from the number you would see on our page for a neighboring town. Here is how the job profiles break down:
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1990s family neighborhoods; 2-story standard.
Newer subdivisions with HOA standards.
Smaller subdivision with creek-side homes.
Established 1970s neighborhood with mature trees; heavier pollen.
Family-friendly subdivisions with consistent home profiles.
Larger executive homes; bigger window counts, custom builds.
See every neighborhood and the full local guide on our Centennial window cleaning page.
Colorado's freeze-thaw cycle is brutal on siding and stucco — water gets into hairline cracks during the day and freezes at night, expanding the cracks and creating perfect conditions for algae and mildew to colonize. Annual soft-wash kills the colonization at the root.
North-facing walls get little direct sun and stay damp longer after snow or rain — that's where Front Range homes show the worst biological staining. Soft-wash is the only safe way to clean these surfaces without damaging the substrate.
Heavy hail (Boulder, Fort Collins, Loveland) — hail-dimpled siding catches more biological growth in the dimples. Post-hail soft-wash slows the colonization significantly.
Pressure washing uses force; soft washing uses chemistry at low pressure. Hard surfaces like Centennial driveways and walks take pressure fine. Walls — siding, painted surfaces, stucco — should never take it, because pressure drives water into the assembly where it causes damage that shows up later. Soft washing cleans those surfaces more thoroughly and does not put moisture where it does not belong.
A season to two years depending on exposure. North and shaded elevations regrow first because they hold moisture. The reason a soft wash lasts longer than a pressure wash is that the solution kills the organic growth rather than just removing what is visible — pressure leaves the biology behind and it comes back within months.
Soft wash uses low pressure (~500 PSI) and a biocidal cleaning solution. Pressure wash uses high pressure (~3,000 PSI) and mechanical force. Soft-wash is for siding, stucco, painted wood — anything that high pressure could damage. Pressure wash is for concrete, brick, and other durable hard surfaces.
Most homes run $300–$800. A typical 2-story 2,000 sqft home is $400–$550. Bundling with window cleaning saves 10-15% on both. Larger homes (3,000+ sqft) or full-property bundles run higher.
No, when done properly. We pre-rinse plants and lawn before applying the biocide, use a surfactant during application, and do a full final rinse so nothing accumulates. Plants are the same green color when we leave as when we arrived.
It kills the current colonization completely. New algae will eventually colonize again — typically 12-18 months in Colorado, faster on north-facing walls in shaded yards. Annual or bi-annual soft wash keeps it at bay.
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