Soft Wash and Exterior Cleaning: A Practical Home Guide

Quick take — the tl;dr (read this first)

Soft wash and exterior cleaning is low-pressure house washing that uses cleaning solutions, not brute force.

• Use soft washing on roofs, siding, stucco, brick, and painted wood. Use pressure washing for concrete, driveways, and brick patios.
• Typical price ranges: about $0.15–$0.80 per sq ft. A full house often runs $450–$1,200. A roof typically costs $200–$900, depending on size and pitch.
• DIY is reasonable for one-story vinyl siding if you’re comfortable with ladders and chemicals. Hire a pro for two-story homes, steep roofs, or solar panels.
• Ask any contractor for SDS (safety data sheets), proof of insurance, a line-item quote, and a re-treatment window.
• Bay Area note: California Glass & Solar is a woman-owned, local team with 12+ years’ experience, free estimates, eco-minded soft washing, and in-house tools.

What is soft wash and exterior cleaning?

Soft wash and exterior cleaning is a mindset more than a machine. The idea is simple: kill the organism. Remove gently. Don’t blast the surface.

Technically, soft washing means low-pressure application—often well under 500 PSI—paired with cleaning solutions and biocides. The foam or solution dwells. It breaks down algae, mildew, moss, and organic grime at the root. Then you rinse, gently.

Why this matters to you: pressure can remove paint, strip shingle granules, warp vinyl, and loosen mortar. Soft washing avoids those risks. It also lasts longer because it addresses the living thing that keeps coming back.

Soft wash vs pressure wash — the simple comparison

They both clean. They approach the problem differently. One uses chemistry and patience. The other uses force and speed.

If you want a clear comparison of the two approaches, see this guide on soft washing vs pressure washing for a straightforward breakdown of when to choose each method.

Simple rule

If the surface can be dented, peeled, or lose protective granules under a strong blast, use soft washing.

Which surfaces are safe for soft washing — a practical surface guide

Soft washing covers most of the delicate surfaces around your home. Here’s what works, and how we handle it.

Asphalt shingle roofs (roof soft wash)

Asphalt shingles get dark streaks from algae (gloeocapsa). The streaks are biological. The fix is chemical and gentle.

Soft washing removes algae without blasting away granules. We apply a diluted sodium hypochlorite solution, allow time to work, then rinse carefully. Plant protection and runoff neutralizers are standard. That protects landscaping and metal fixtures. For more on how the process works on a technical level, read about the science behind a thorough soft wash.

Vinyl siding

Vinyl warps and dents under high-pressure. Soft washing cleans dirt, mold, and mildew without damage. Use a low-pressure sprayer and a mild solution. Test a small area first.

Stucco and EIFS

Stucco is textured and fragile. A soft wash preserves texture and finish. Scrubbing is rarely needed. Let the chemistry do the work.

Brick and masonry

Brick is durable but porous. Soft washing can remove biological staining and restore color without aggressive scrubbing. For deep-set oil or paint, pressure work or specialty treatment may be needed.

Wood (painted or sealed)

Soft washing is safe on painted and sealed wood when used with compatible cleaners and low pressure. For bare wood decks you may want a different approach—soft wash first, then low-pressure sanding or restoration if needed.

Metal roofs and gutters

Start with gentle chemistry. Rinse to prevent chloride buildup. Proper dilution and fast rinsing protect metal from corrosion.

Quick rule

If a high-pressure wash would reduce the surface’s protective layer, use soft washing instead.

Soft wash and exterior cleaning costs — what to expect

Price is practical. It’s not mysterious. Expect a range, not a fixed number. The right quote explains why.

Typical ranges:

• Per sq ft: $0.15–$0.80
• Roof soft wash: $200–$900 (size, pitch, and story count matter)
• Full house exterior: $450–$1,200

Cost drivers to watch:

• Height and number of stories — two-story work costs more because of time, ladder safety, and fall protection.
• Roof pitch and material — steep or fragile roofs add cost.
• Level of contamination — heavy moss or decades of growth takes longer.
• Access and protection — scaffolding, plant protection, and containment add time and cost.
• Local market — Bay Area labor is pricier than rural areas.

What a transparent quote includes

• Line items (roof, siding, gutters, solar panels) with square footage or roof size.
• Chemical types and SDS availability.
• Plant protection and runoff neutralization steps.
• Cleanup, disposal, and a re-treatment or inspection window.

Screenshot-ready sample estimate (example)

Note: This is an illustrative example for a Bay Area job. Actual quotes vary. Ask the contractor for a written, line-item estimate you can screenshot or save.

How long results last and the right maintenance schedule

Soft wash lasts because it targets biology. But it’s not permanent. Expect variation based on site conditions.

• Roofs: generally 3–5 years between treatments in many climates. Shade and trees shorten that window.
• Siding: check annually. Clean every 1–4 years depending on moisture and exposure.
• High-humidity or shaded homes: plan for cleaning every 2–3 years, or sooner if growth returns.
• Solar panels: often cleaned 1–2 times per year, depending on dust, pollen, and bird activity.

Practical tip: inspect after storms and in spring. Don’t wait until streaks or moss have done structural damage.

Chemicals, safety, and environmental concerns

Chemistry is what makes soft washing effective. It’s also what requires care.

Common ingredients

• Sodium hypochlorite (household bleach in professional concentration)
• Surfactants to help chemicals cling and penetrate
• Neutralizers and plant protectants
• Occasional odor maskers or boosters

Professionals often start with a concentrated sodium hypochlorite (e.g., ~12.5%) and dilute it to working strengths. Typical working concentrations are in the neighborhood of ~3% for roofs and ~1% for siding, but check product labels and SDS for exact guidance.

Environmental and safety notes

• Sodium hypochlorite is reactive and toxic to aquatic life in its undiluted form. That’s why containment and neutralization matter.
• Some by-products degrade during wastewater treatment. But you shouldn’t assume runoff is safe. Ask your contractor about containment and neutralizers.
• Request SDS for every product. A reputable contractor will hand them over without hesitation.
• Pre-wet plants. Use protective sheeting. Apply neutralizers promptly where needed.
• Keep pets and children away until rinses are complete and diluted to safe levels. Use recommended PPE.
• Local rules matter. In California, municipal rules and stormwater permits may apply. Ask the contractor what they follow.

For detailed manufacturer safety summaries on oxidizers commonly used in the trade, see this hydrogen peroxide and sodium hypochlorite safety summary.

Marketing claims like “eco-friendly” or “biodegradable” are common. Don’t take the label alone. Ask for product literature and SDS. A good contractor will be transparent.

DIY — when you can do it, and a safe step-by-step

DIY works sometimes. It’s cheaper. But it isn’t always safe or sensible.

When DIY is reasonable

• Single-story homes with easy access
• Low roof pitch
• Quality ladder skills and comfort with handling chemicals

When to hire a pro

• Two-story homes or steep roofs
• Solar panels or complex arrays
• Fragile or slate roofs
• If you don’t carry insurance for falls or chemical exposure

DIY high-level steps

1. Inspect surfaces for damage. Don’t clean damaged shingles or peeling paint—repair first.
2. Protect plants and outdoor furniture. Pre-wet vegetation and lay sheeting where runoff collects.
3. Use proper equipment: a softwash system or a pump that can keep pressure under 500 PSI (many pros run far lower for house surfaces).
4. Mix chemicals safely. Check product SDS. Wear gloves, eye protection, and a respirator if recommended.
5. Test a small, out-of-the-way area and wait for results.
6. Apply solution, let it dwell per label instructions, then rinse top-to-bottom gently.
7. Neutralize runoff if the product calls for it. Rinse plants after treatment if you used plant protectors that require follow-up.
8. Clean up and store chemicals safely. Keep SDS with the product at home.

Tools and gear checklist

• Softwash system or low-pressure pump and wide-angle nozzles
• Telescoping wand and soft brushes
• PPE: goggles, gloves, chemical-resistant clothing
• Tarps and protective sheeting
• Containment and neutralizer products
• SDS sheets for each chemical

Red flag for DIY: never use a high-pressure washer with bleach on shingles or painted surfaces. That combination causes real damage.

How to hire exterior house cleaning services — exact questions to ask

Hire by questions, not promises. Bring a tape measure and your checklist. Insist on an on-site estimate.

Must-ask questions

1. Do you carry general liability and workers’ compensation? What are the policy limits? Ask for certificates.
2. Can you provide the SDS for the products you plan to use?
3. What exact soft wash process do you use and what PSI will you operate at?
4. Do you have specific experience with roofs, stucco, and solar panels? Ask for local references.
5. How do you protect plants, irrigation systems, and metal fixtures?
6. What is included in the written quote? Any potential add-ons?
7. Do you offer a warranty or a re-treat for recurring algae? What are the terms?
8. Can you provide before/after photos of similar jobs?

What a good provider will show you

• Sample SDSs and product literature
• Proof of insurance
• Detailed written contract and timeline
• Clear, itemized pricing and a re-treatment window

Red flags

• Refusal to provide SDS
• No insurance or unwillingness to share certificate
• Vague descriptions like “we’ll just pressure-wash it” for delicate surfaces
• “Spray and run” behavior with no containment plan

If you need professional pressure work rather than soft washing, consider contacting Expert Pressure Washing Services in The Bay Area | CGS for a local, experienced quote.

Solar panels and soft washing — the extra considerations

Solar panels are not just glass. They’re electrical arrays with frames, wiring, and electronics nearby. Clean them right.

Best practices include purified or deionized water and soft brushes to avoid scratching anti-reflective coatings. We avoid harsh chemicals on panels. Purified-water rinses leave no mineral residue that could reduce output.

Cleaning often improves output. How much depends on dust, pollen, bird droppings, and local conditions. In dusty or construction-heavy areas, cleaning twice a year may be sensible.

Questions to ask about panel cleaning

• Do you use purified or deionized water?
• Do you use non-abrasive brushes and soft-hand techniques?
• How do you avoid damaging frames, wiring, and microinverters?
• Do you offer bird or pest deterrence to keep panels clear longer?

California Glass & Solar note: our solar cleaning uses purified water and soft brushes, and we offer humane bird deterrents to reduce re-soiling. We design and use custom tools in-house to match each roof and array. For a full list of our offerings, see Services, California Glass and Solar.

What a proper quote looks like (sample line items)

Good quotes are granular. They answer two questions: what you get, and why it costs what it costs. A good contractor gives you both.

Ask for the quote by email. Keep it. It’s a record for resale and warranty questions.

Short case examples (realistic, modest)

Shady bungalow

Problem: black algae and heavy shade.

Approach: roof soft wash and siding soft wash, pre-wet plants, neutralizer, and a 4-year maintenance plan.

Result: clean roof, homeowner satisfied, fewer leaks and less moss migration into gutters.

Small solar array on a suburban home

Problem: dusty panels after a nearby landscaping project.

Approach: purified-water rinse and soft-brush cleaning.

Result: noticeable output improvement at next read. Panels stayed cleaner longer after bird-deterrent placement.

Checklist for homeowners — deciding, hiring, and aftercare

Keep this checklist on your phone when you call contractors.

Decide

• Is the surface delicate? If yes, prefer soft washing.
• Is the job tall or complex? If yes, hire a pro.

Hire

• Get an on-site estimate and an itemized, written quote.
• Ask for SDS and proof of insurance (GL and WC).
• Confirm plant protection and runoff handling procedures.
• Ask about the re-treatment or warranty window.

Aftercare

• Set an inspection interval (annual check; clean every 2–5 years depending on conditions).
• Keep before/after photos and your invoice for resale value.
• Record any follow-up commitments in writing.

Final word — simple rules for less fuss and more life

Don’t default to pressure. Pressure is loud and fast. It isn’t always right.

If it’s tall, steep, or solar, call a pro. If it’s single-story vinyl and you’re confident, DIY carefully.

Require transparency: SDS, insurance certificates, and a re-treat promise. These are not optional. They’re basic.

If you’re in the Bay Area and want a free estimate, California Glass & Solar is woman-owned, local, and has 12+ years of experience. We make our tools in-house, use eco-minded soft washing techniques, and offer purified-water solar cleaning. Ask for our hiring checklist and SDS during your estimate. Learn more About California Glass and Solar | The Bay Area Experts.

Save the screenshot of the sample quote above. Use the checklist. Ask the right questions. Your home lasts longer when you clean it the right way.

Next step: Use the attached checklist, screenshot the sample quote for reference, and call for a free estimate if you want a local, experienced team to look at your house. View our Services, California Glass and Solar or run a quick lookup via Search, California Glass and Solar to schedule.