Pressure washing uses high-pressure water (1,500-3,000 PSI) while soft washing uses low-pressure water (100-500 PSI) with biodegradable cleaning solutions. Here is which method is right for your commercial building.
Pressure washing and soft washing are two distinct exterior cleaning methods, each suited for different surfaces and conditions. Pressure washing uses water at 1,500-3,000 PSI to blast away dirt, grime, and stains. Soft washing uses low pressure (100-500 PSI) combined with specialized biodegradable cleaning solutions to kill and remove mold, mildew, algae, and other organic growth. Choosing the wrong method can damage building surfaces — making this one of the most important decisions for commercial property maintenance.
What Is Pressure Washing?
Pressure washing is powered by a gas or electric pressure washer that delivers high-pressure water through a spray wand. The high pressure physically dislodges dirt, oil, gum, and other stubborn contaminants from hard surfaces. Water flow rates range from 2-4 gallons per minute. Pressure washing is fast and effective on durable, non-porous surfaces. It does not typically use cleaning chemicals, relying instead on water pressure alone. Standard nozzles produce a 0-degree (concentrated) to 40-degree (wide) spray pattern. For most commercial pressure washing, a 25-40 degree tip at 2,000-3,000 PSI is used for concrete and brick surfaces.
What Is Soft Washing?
Soft washing uses a low-pressure pump system (100-500 PSI) with application of a biodegradable cleaning solution, typically a sodium hypochlorite (bleach) and surfactant blend. The solution kills mold, mildew, algae, moss, and bacteria at the root. It is then rinsed with low-pressure water. Because soft washing kills the organic material rather than just blasting it off, results last 2-3 times longer than pressure washing. The low pressure prevents damage to delicate surfaces like roof shingles, painted siding, stucco, and wood.
When to Use Pressure Washing
Concrete sidewalks, walkways, and plazas: Pressure washing at 2,500-3,000 PSI removes gum, oil stains, and heavy dirt. Best method for flatwork concrete with no paint or sealant damage risk.
Parking lots and garages: Pressure washing at 2,000-3,000 PSI for oil stain treatment and general cleaning. Combined with degreasers for heavy stains.
Brick and stone building exteriors: Pressure washing at 1,200-1,800 PSI (lower pressure for older mortar). Use wide fan spray to avoid mortar damage.
Dumpster enclosures: Pressure washing at 2,500+ PSI with degreaser for heavy grime.
Loading docks: Pressure washing for grease and oil stains.
When to Use Soft Washing
Roof surfaces (asphalt shingle, tile, metal): Soft washing only. High pressure damages shingles and voids roof warranties. Soft washing kills algae and moss effectively.
Painted surfaces (siding, trim, railings): Soft washing at 100-400 PSI. High pressure strips paint and damages wood or fiber cement.
Stucco and EIFS exteriors: Soft washing at 200-500 PSI. Stucco is porous and easily damaged by high pressure.
Vinyl siding: Soft washing preferred. If using pressure, keep below 1,000 PSI with wide fan spray.
Wood surfaces (decks, fences, pergolas): Soft washing preferred or low pressure (600-1,000 PSI) with wide fan spray. High pressure damages wood grain.
Windows and screens: Soft washing only.
Cost Comparison: Pressure Washing vs. Soft Washing
Pressure washing: $0.15-$0.35 per square foot for standard concrete surfaces. Faster process — crews clean more area per hour. Results last 6-12 months for concrete, less for surfaces with ongoing organic growth. Less expensive per cleaning but may need more frequent service.
Soft washing: $0.25-$0.60 per square foot. Solution cost and slower application increase price. Results last 2-3 times longer — up to 18-24 months for roofs and siding. Often more cost-effective over time due to longer-lasting results.
For a 10,000 sq ft building exterior with mold growth: pressure washing at $0.25/sq ft = $2,500, needed every 12 months = $2,500/year. Soft washing at $0.40/sq ft = $4,000, needed every 24 months = $2,000/year. Soft washing saves $500/year while providing better results.
Can You Combine Both Methods?
Yes — many commercial properties benefit from a hybrid approach. A typical strategy: soft wash building exteriors, roofs, and painted surfaces; pressure wash concrete areas, parking lots, and durable surfaces. Some providers offer combined services with a single mobilization fee. RBM provides both commercial pressure washing and exterior soft washing across all service areas.
When getting bids, ask vendors about their approach for each specific surface on your property. A vendor that recommends the same method for all surfaces may not have the expertise needed for proper commercial exterior care.
Choose the right exterior cleaning method for your building. Contact RBM for a free assessment.
Final Thoughts
Both pressure washing and soft washing have their place in commercial building maintenance. The correct method depends on surface type, condition, the type of soiling, and desired longevity of results. A professional exterior cleaning company should offer both methods and recommend the right approach for each surface on your property.
Since 1974, RBM provides commercial pressure washing, window washing, janitorial services, and building maintenance across Utah, Arizona, Nevada, and Texas. Call 800.403.3564 or contact us.
