What's the difference between pressure washing and soft washing?

Pressure washing uses high water pressure (~3,000 PSI) to mechanically remove dirt from durable hard surfaces like concrete, brick, and stone. Soft washing uses low pressure (~500 PSI) combined with a biocidal cleaning solution that chemically kills mildew, algae, and bacteria on softer surfaces like vinyl siding, stucco, and painted wood. Soft wash is the right tool when high pressure could damage the surface; pressure wash is the right tool when mechanical force is needed.

Will pressure washing damage my vinyl siding or stucco?

Yes, it absolutely can. High-pressure water on vinyl siding can crack the panels at their seams, force water behind the siding into the substrate, and tear caulking. On stucco, high-pressure water erodes the textured finish and pushes water into hairline cracks where it freezes overnight — accelerating damage. This is why responsible cleaning companies always soft-wash these surfaces. If a contractor offers to pressure wash your siding, find a different contractor.

Can I rent a pressure washer and do this myself?

You can rent a unit (~$70/day) and clean a concrete driveway safely with practice. But soft-washing siding correctly requires the right biocidal solutions, surfactants, and rinse-down technique to avoid plant damage and streaking — most DIY soft-wash attempts leave visible streak lines on the siding. For most homeowners, the time, equipment, and risk of damage make professional service the better choice for siding/stucco. Concrete-only DIY is reasonable.

How much does soft wash cost in Denver?

A typical 2-story 2,000 sqft Denver home runs $400-$550 for full house soft wash (siding + trim + soffit + fascia). Whole-property bundles (driveway pressure wash + house soft wash + deck + fence) run $700-$1,500 depending on scope. Get an exact instant quote on our website in 30 seconds.

How long does pressure washing or soft wash last?

Pressure washing concrete: 12-18 months before re-soiling. Soft wash on siding: 18-30 months before biological growth (algae/mildew) returns. North-facing walls in shaded yards re-colonize faster — sometimes 12 months — while sun-exposed south-facing walls can stay clean 3+ years.

Is the cleaning solution safe for plants and pets?

When applied properly, yes. The biocidal solution we use (sodium hypochlorite-based) is biodegradable and breaks down within hours. We pre-rinse plants and lawn before applying biocide, use a surfactant during application, and do a full final rinse so nothing accumulates. Pets should stay indoors during the wash itself but it's safe within an hour.

Do I need both pressure washing and soft wash?

Most Colorado homes do, eventually. Concrete (driveway, sidewalks, patio) needs periodic pressure washing — annually if heavily used. Siding and stucco need soft wash every 18-30 months to kill algae and mildew. Many homeowners bundle both into a single half- or full-day service every year or two for a 10-15% bundle discount.

Why does soft wash cost about the same as pressure washing if it uses lower pressure?

Soft wash is more labor-intensive than pressure washing, even though the pressure is lower. The cleaning solution has dwell time (5-15 minutes per section), plants and lawn need pre-rinse and post-rinse, the technique requires top-down work to prevent streaking, and the biocide chemistry is more expensive than plain water. The price reflects the labor + chemistry, not the pressure.

Pressure Washing vs. Soft Wash: When to Use Each (Colorado Guide)

The most common mistake homeowners make hiring exterior cleaners is asking for “pressure washing” when what they actually need is soft wash. Or worse — hiring a contractor who pressure washes vinyl siding because that's the only tool they own, and damages the home in the process.

This guide covers the difference, when to use each method, what they cost, and how to recognize when your contractor is using the wrong one.

By Jamison Weise, Owner — Sonlight Window Cleaning. Updated May 2026.

Quick answer

Use pressure washing on durable hard surfaces (concrete, brick, stone). Use soft wash on softer surfaces (siding, stucco, painted wood). Most Colorado homes need both — pressure washing every 12-18 months on concrete, soft wash every 18-30 months on the house exterior.

The Two Methods

Pressure Washing

Pressure: 2,500-3,500 PSI (pounds per square inch).

Mechanism: Mechanical force. Water hits the surface hard enough to physically blast away dirt, oil, mildew, and ground-in stains.

Right surfaces: Concrete (driveways, sidewalks, patios, garage floors), brick, natural stone, stamped concrete, paver walkways. Anything that won't crack, splinter, or embed water under high pressure.

Wrong surfaces: Vinyl siding (cracks at seams), stucco (erodes finish, embeds water), painted wood (peels paint), cedar shingles (splinters), composite decking (strips finish), window glass (can break tempered units).

Soft Wash

Pressure: 200-800 PSI — about 1/5 of pressure washing. Most professional soft-wash systems are around 500 PSI.

Mechanism: Biocidal chemistry. A sodium hypochlorite-based cleaning solution (industry standard) is applied with low pressure, given dwell time (5-15 minutes), then rinsed off. The solution kills mildew, algae, lichen, and bacteria at the cellular level — the dirt and biological growth are dead before the rinse-down even touches the surface.

Right surfaces: Vinyl siding, fiber-cement (Hardie) siding, stucco, EIFS, painted wood, brick (if mortar is fragile), composite siding, painted decks, fences, soffits, fascia.

Wrong surfaces: Concrete (chemistry doesn't dig deep enough into porous material to remove ground-in oil and dirt), heavily oxidized metal (won't reverse oxidation).

How to Tell Which Method You Need

Walk around your house and look at what's actually dirty. The contamination tells you which method:

Signs you need pressure washing:

• Concrete driveway has black tire tracks, oil stains, or general grime
• Sidewalks and patios have ground-in dirt that won't come up with hose-and-broom
• Brick walks or stone patio have moss growing in joints
• Garage floor has accumulated greasy buildup
• Stamped concrete has lost its color uniformity

Signs you need soft wash:

• Black or green streaks on north-facing siding (algae)
• Green tint on stucco, especially in shaded areas (algae)
• Black spots or general darkening of vinyl siding (mildew)
• Lichen growth on fiber-cement siding (most common in Colorado's freeze-thaw cycle)
• Wood deck has black mildew between boards or in shaded sections
• Soffits and fascia have visible discoloration

Most Colorado homes have BOTH — concrete that's grimy and siding that's mildewed. That's why we usually recommend a bundled service: pressure wash the hardscape, soft wash the house, and bundle in window cleaning while the crew is already there.

What Pressure Washing Can't Do

Pressure washing removes what's on the surface mechanically. It does not kill what caused it.

When you pressure-wash mildewed siding (assuming the siding survives), you remove the visible black stain — but the mildew spores are still there in the surface pores. They'll re-colonize within 90-120 days, sometimes faster. You're treating the symptom, not the cause.

Soft wash uses biocidal chemistry that kills the spores and prevents re-colonization for 18-30 months. That's the fundamental difference: pressure removes, soft wash kills + removes.

For pure dirt (no biological growth), pressure wash works fine. For biological staining, you need soft wash. In Colorado's freeze-thaw climate, most exterior staining IS biological — so soft wash is the more common need.

Cost Comparison (Colorado Front Range, 2026)

Service	Typical price range
Driveway pressure wash (single)	$150–$250
Driveway + sidewalks pressure wash	$250–$400
Full house soft wash (1,800 sqft)	$400–$550
Full house soft wash (2,500 sqft)	$500–$700
Whole property bundle (driveway + house + deck)	$700–$1,500
Bundle + window cleaning	10-15% off both

Bundling is the right move for most homeowners — one half-day visit covers everything, and the discount makes both services cheaper than booking separately. We see 70% of our customers choose a bundle.

How to Vet a Contractor

Before you hire any pressure-washing contractor in Colorado, ask:

“Do you offer soft wash?” If they only own a pressure washer, they will pressure wash your siding regardless of what's appropriate. Hard pass.
“What chemistry do you use for siding?” The right answer mentions sodium hypochlorite (industry-standard biocide) and a surfactant. If they say “just water,” they don't do real soft wash.
“What pressure do you use on stucco?” The right answer is 500 PSI or less, plus biocide. If they quote anything over 1,500 PSI for stucco, find someone else.
“Are you fully insured?” $1M+ general liability minimum. Ask for a Certificate of Insurance before service. If a contractor damages your siding, you want their insurance to cover it.
“What's your warranty?” A competent contractor will guarantee their work for at least 24 hours after the job. Sonlight's guarantee is 24 hours — if anything looks off, we come back free.

Get an Instant Pressure Wash + Soft Wash Quote

Enter your address and our autoquoter returns a real, firm price for any combination of pressure wash, soft wash, window cleaning, and gutter cleaning in 30 seconds.

Get My Free Quote →

Frequently Asked Questions

What's the difference between pressure washing and soft washing?: Pressure washing uses high water pressure (~3,000 PSI) to mechanically remove dirt from durable hard surfaces like concrete, brick, and stone. Soft washing uses low pressure (~500 PSI) combined with a biocidal cleaning solution that chemically kills mildew, algae, and bacteria on softer surfaces like vinyl siding, stucco, and painted wood. Soft wash is the right tool when high pressure could damage the surface; pressure wash is the right tool when mechanical force is needed.
Will pressure washing damage my vinyl siding or stucco?: Yes, it absolutely can. High-pressure water on vinyl siding can crack the panels at their seams, force water behind the siding into the substrate, and tear caulking. On stucco, high-pressure water erodes the textured finish and pushes water into hairline cracks where it freezes overnight — accelerating damage. This is why responsible cleaning companies always soft-wash these surfaces. If a contractor offers to pressure wash your siding, find a different contractor.
Can I rent a pressure washer and do this myself?: You can rent a unit (~$70/day) and clean a concrete driveway safely with practice. But soft-washing siding correctly requires the right biocidal solutions, surfactants, and rinse-down technique to avoid plant damage and streaking — most DIY soft-wash attempts leave visible streak lines on the siding. For most homeowners, the time, equipment, and risk of damage make professional service the better choice for siding/stucco. Concrete-only DIY is reasonable.
How much does soft wash cost in Denver?: A typical 2-story 2,000 sqft Denver home runs $400-$550 for full house soft wash (siding + trim + soffit + fascia). Whole-property bundles (driveway pressure wash + house soft wash + deck + fence) run $700-$1,500 depending on scope. Get an exact instant quote on our website in 30 seconds.
How long does pressure washing or soft wash last?: Pressure washing concrete: 12-18 months before re-soiling. Soft wash on siding: 18-30 months before biological growth (algae/mildew) returns. North-facing walls in shaded yards re-colonize faster — sometimes 12 months — while sun-exposed south-facing walls can stay clean 3+ years.
Is the cleaning solution safe for plants and pets?: When applied properly, yes. The biocidal solution we use (sodium hypochlorite-based) is biodegradable and breaks down within hours. We pre-rinse plants and lawn before applying biocide, use a surfactant during application, and do a full final rinse so nothing accumulates. Pets should stay indoors during the wash itself but it's safe within an hour.
Do I need both pressure washing and soft wash?: Most Colorado homes do, eventually. Concrete (driveway, sidewalks, patio) needs periodic pressure washing — annually if heavily used. Siding and stucco need soft wash every 18-30 months to kill algae and mildew. Many homeowners bundle both into a single half- or full-day service every year or two for a 10-15% bundle discount.
Why does soft wash cost about the same as pressure washing if it uses lower pressure?: Soft wash is more labor-intensive than pressure washing, even though the pressure is lower. The cleaning solution has dwell time (5-15 minutes per section), plants and lawn need pre-rinse and post-rinse, the technique requires top-down work to prevent streaking, and the biocide chemistry is more expensive than plain water. The price reflects the labor + chemistry, not the pressure.