Soft washing removes algae, moss, and buildup from commercial roofs and siding without the high-pressure damage that traditional power washing causes. If you own or manage a commercial property, you've probably noticed dark streaks, green growth, or discoloration that makes your building look neglected—soft washing fixes that while actually protecting your investment. It's a specialized process that differs significantly from standard cleaning, and choosing the right contractor matters.
Why Commercial Roofs and Siding Need Soft Washing
Commercial buildings take a beating from weather, UV exposure, and biological growth. Algae and moss don't just look bad; they retain moisture against your roof and siding materials, accelerating deterioration. Power washing at 3,000+ PSI can strip paint, crack siding, or damage shingles, especially on older roofs. Soft washing uses low-pressure water (typically 500 PSI or less) combined with biodegradable cleaning solutions designed to break down organic growth without forcing water into seams or under materials.
The result is a genuinely clean surface that stays cleaner longer—most soft-washed buildings need treatment only every 2–3 years, compared to annual power washing for some competitors' work.
What the Soft Washing Process Looks Like
A legitimate commercial soft washing job follows a specific workflow. The contractor first applies a pre-treatment solution to the roof or siding, letting it sit for 15–30 minutes to chemically break down algae and moss at the root. They then rinse with low-pressure water, working methodically to avoid pooling or runoff into landscaping. Post-treatment may include an algae inhibitor to slow regrowth. The whole process typically takes 4–8 hours for a 5,000–10,000 sq. ft. commercial roof, depending on complexity and soiling level.
Reputable providers will also:
- Inspect gutters and downspouts beforehand and clean them as part of the job
- Use eco-friendly, biodegradable cleaners that don't harm landscaping or water runoff
- Apply protective sealant or algae inhibitor after rinsing (standard on quality jobs)
- Provide written documentation of what was treated and when
- Carry liability insurance covering roof work
Cost Expectations for Commercial Soft Washing
Pricing varies by region and property size, but typical commercial roof soft washing runs $0.50–$1.50 per square foot. A 10,000 sq. ft. roof usually costs $5,000–$15,000, though complex roofs with multiple levels, skylights, or heavy moss growth may run higher. Siding-only jobs are often cheaper, ranging from $0.30–$0.80 per square foot.
Get at least three quotes and compare what's included. Some contractors bundle gutter cleaning; others charge separately ($500–$2,000 depending on building size). Roof washing with algae inhibitor treatment costs slightly more upfront but saves money over time by extending the interval between cleanings.
What to Look for in a Soft Washing Contractor
Don't assume all exterior cleaning companies understand soft washing. Ask specifically whether they:
- Use low-pressure equipment (pump-fed sprayers, not pressure washers)
- Have commercial-grade liability and workers' comp insurance
- Can show photos of similar commercial projects they've completed
- Offer a warranty on their work (typically 1–2 years against algae return)
- Use biodegradable, commercial-grade cleaning solutions (not homemade or grocery-store degreasers)
Red flags include contractors who quote only on phone calls without visiting your property, those pushing you to decide the same day, or anyone unwilling to explain their cleaning solutions. A professional will schedule a site inspection and provide a detailed scope of work.
Timing and Maintenance
The best time to soft wash a commercial roof is late spring or early fall when weather is mild and dry. Avoid winter or rainy seasons—the treatment needs to cure for 48 hours without heavy moisture. After cleaning, establish a maintenance plan: most commercial buildings benefit from soft washing every 2–3 years, or sooner if you're in a humid climate or shaded area where moss thrives.
If you're comparing soft washing providers in your area, platforms like Mercoly let you view trusted contractors side by side, check their pricing, and read verified reviews from other commercial property managers.
Frequently Asked Questions
Q: Will soft washing damage my roof or void the warranty? No—soft washing with proper low-pressure techniques is safe and won't void manufacturer warranties. High-pressure washing is what causes damage; soft washing is specifically designed to avoid it.
Q: How long does soft-washed algae stay off my roof? With a quality algae inhibitor applied post-treatment, you'll typically see 2–3 years before regrowth becomes noticeable, though results depend on climate and shade.
Q: Is soft washing safe for all siding materials? Yes, when done by a trained contractor. Soft washing works safely on asphalt shingles, metal siding, vinyl, stucco, and wood—the low pressure and appropriate cleaners protect each material type.
Get quotes from vetted soft washing providers today to protect your commercial property's appearance and lifespan.