For most house exteriors, soft washing is the safer choice. It uses low pressure and a cleaning solution to kill mould, algae and mildew on siding, stucco, wood and shingles. Pressure washing uses force, and it belongs on hard, durable surfaces such as concrete driveways, stone patios and brick. If you are washing a house before painting or staining, the method you pick decides whether the new finish bonds well or fails early.
This guide explains how each method works, what pressure counts as “soft”, which surfaces suit which method, what it costs in the Toronto area, and how often to repeat it.
TL;DR
- Soft washing means low pressure (generally 100 to 500 PSI) plus a cleaning solution that treats organic growth. Pressure washing means high pressure, typically 1,500 to 4,000 PSI, to blast off dirt.
- Use soft washing for vinyl, aluminum, wood siding, stucco and asphalt shingles. Use pressure washing for concrete, stone and hard masonry.
- In Toronto and the GTA, published soft-wash prices for a detached house run roughly $400 to $800, depending on size and storeys.
- High pressure can push water behind vinyl siding, strip wood fibre and damage paint, so a wash before repainting should be gentle and followed by full drying time.
- Homes built before 1991 may have lead-based paint. Do not scrape or sand it as part of “prep”.
Table of Contents
- The real difference between the two methods
- What PSI counts as soft washing?
- Which method suits which surface
- Risks of each method
- How much does it cost in the Toronto area?
- How often should a house be soft washed?
- Do you rinse the roof after soft washing?
- Washing before you paint or stain
- How to choose: a quick decision guide
- What we do for GTA homes
- FAQ
- Sources
The real difference between the two methods
Both methods use water, and both clean. The difference is what does the work.
Pressure washing relies on mechanical force. A narrow jet of high-pressure water knocks dirt, mud and loose material off a surface. Soft washing relies on chemistry. Low-pressure water carries a detergent or sodium hypochlorite solution onto the surface, the solution breaks down the organic growth, and a gentle rinse finishes the job. One Canadian cleaning company describes the split as detergents dissolving organic growth versus water force blasting away stubborn grime.
That is why the same house often needs both. The siding has green algae and black mildew in the shaded corners, which is a biology problem. The driveway has tire marks, oil and packed dirt, which is a force problem.
You will also see “power washing” in quotes. It is usually the same as pressure washing, with the water heated. Heat helps with grease on concrete. It is not what you want on siding.
What PSI counts as soft washing?
There is no legal definition, so numbers vary by source. Reasonable ranges from Canadian and US cleaning publications:
| Method | Typical pressure | What it does |
|---|---|---|
| Soft washing | 100 to 500 PSI; some sources say 150 to 300 PSI | Chemical solution treats organic growth; water mostly carries and rinses |
| Pressure washing | 1,500 to 4,000 PSI (another source gives 1,300 to 2,800 PSI) | Water force removes dirt and loose debris |
The pressure matters, but so does how the solution is applied. A pressure washer fitted with a wider tip can lower its output, but a lower-pressure tip alone is not the same as a treatment that kills growth. The solution is what separates the two jobs.
Which method suits which surface
Use this as a starting point, then check your siding manufacturer’s maintenance guide.
| Surface | Better method | Why |
|---|---|---|
| Vinyl and aluminum siding | Soft wash | Delicate surfaces where mould and algae are the problem |
| Wood siding and painted wood | Soft wash | High pressure can remove surface fibre and damage painted wood |
| Stucco | Soft wash | High pressure can damage stucco |
| Asphalt shingles | Soft wash | Pressure washing is said to void most roof warranties |
| Concrete driveways, walkways | Pressure wash | Hard surfaces that withstand high-impact water |
| Stone patios, hard brick | Pressure wash, with care | Durable, but use the lowest pressure that works |
| Composite siding (CanExel type) | Gentle wash per manufacturer | The maker warns against pressure washers and bleach or ammonia cleaners to keep warranty coverage |
The last row is the one people miss. A manufacturer’s maintenance guide beats any general rule. If your siding is under warranty, read it before anyone touches the wall.
Risks of each method
Pressure washing risks
The damage from too much pressure is usually invisible at first. Pressure above 1,600 PSI on vinyl siding can force water behind the panels and into the wall cavity. That moisture sits behind the cladding, feeds mould and can later show up as bubbling or peeling paint on adjacent trim. The same source notes that high pressure on wood can strip surface fibre, leaving a fuzzy, rough finish that takes stain unevenly.
On painted surfaces, pressure can lift sound paint along with the loose paint, and it drives water into cracks and joints. If you are heading toward a repaint, that can make a repair job out of what should have been a simple wash.
Soft washing risks
The risk here is the chemistry. Soft-wash solutions are commonly built on sodium hypochlorite, and technicians wear protective equipment because it is not safe for eyes or skin. Runoff matters too: plants near the foundation should be wetted and protected, and neutralizers are often used to limit the effect of runoff on plants and the environment.
Health Canada’s advice for household chemical projects applies if you handle products yourself: check hazard symbols, never mix cleaners, and wear the protective equipment named on the label. Mixing bleach with other cleaners is the classic mistake.
Pressure washer safety
If you own a consumer pressure washer, check it against current recalls. Health Canada has, for example, recalled certain RYOBI electric pressure washers and told owners to stop using them and request a free repair kit.
Older homes and lead paint
If your house was built before 1991, the paint may contain lead. Health Canada says not to sand, scrape or burn off lead-based paint, because that releases harmful dust. A high-pressure blast at flaking paint on an older home can break the paint up and spread chips into the soil. If you suspect old paint, have it tested before any aggressive prep, and use a professional who works with the right containment.
How much does it cost in the Toronto area?
Published local numbers are limited, and every quote depends on access, height, how heavy the growth is and what needs protecting. Two useful reference points:
- In Toronto and the GTA, one local price guide lists soft-wash house washing at $400 to $600 for a one-storey bungalow and $600 to $800 for a two-storey detached home of 2,000 to 2,500 sq. ft.
- A national guide puts soft washing a house at roughly $250 to $700, which is a wider and lower range.
Treat these as ballparks, not quotes. Rural lots and long drives can add trip charges and minimums, so ask for a written, fixed price.
Is soft washing worth the money?
The argument for it is durability. One Canadian source says soft-wash results typically last 3 to 5 years because the solution kills the root structures of organisms, versus 3 to 6 months for a pressure wash that only removes surface debris. That is a company’s claim, and results depend on shade, tree cover and humidity. A north-facing wall under maples will green up faster than a sunny brick face. The sensible way to judge value is by what you are protecting: siding, stucco and shingles are expensive to replace, and a gentle method protects them.
How often should a house be soft washed?
There is no universal schedule. Start with an annual look. Maibec, a siding manufacturer, recommends visually inspecting CanExel siding once a year and cleaning only the areas that need it. That is a sound habit for any siding: inspect each spring, spot-clean what is dirty, and do a full soft wash when growth or staining spreads.
Shaded north and east walls, homes near trees and damp lots usually need attention sooner than open, sunny ones. If the cleaning claims above hold in your case, a full-house soft wash every few years is a reasonable rhythm, with the annual inspection telling you when.
Do you rinse the roof after soft washing?
It depends on the contractor’s process. Some roof-cleaning professionals apply the solution to asphalt shingles and deliberately leave it, letting the next rain do the final rinse, so the treatment keeps working. Walls, windows and plants around the house are a different story: they are normally rinsed so the solution does not dry on glass or harm landscaping. Ask your contractor how they handle each area before the day starts.
Washing before you paint or stain
This is where the choice affects us directly. Paint and stain only bond to a clean, sound, dry surface. Dirt, chalking and mildew under the new coat mean it peels, blisters or discolours early.
For siding, wood and stucco, the gentle approach is almost always right. It removes mildew and surface grime without driving water into the wall or roughing up the wood. Then the house needs time to dry before any coating goes on. Paint on damp substrate is one of the most common reasons for failure, and our guides on power washing before painting and on fixing peeling exterior paint cover the prep in more detail. Stucco has its own rule: see our guide on waiting before painting stucco so moisture is out of the wall first.
Timing matters too. Wash early enough that surfaces dry, then paint inside the temperature window that suits exterior coatings. For deck and fence staining, a gentle clean (never a gouging blast) leaves the wood grain intact so stain absorbs evenly.
Concrete is the exception. A driveway, garage floor or walkway can take pressure, and this is where pressure washing earns its place before a coating such as concrete coating restoration or an epoxy floor.
How to choose: a quick decision guide
- Identify the surface. Soft, painted or organic-growth-prone (siding, stucco, wood, shingles): soft wash. Hard and durable (concrete, stone): pressure wash.
- Identify the problem. Green, black or orange growth: chemistry. Mud, grit, tire marks: force.
- Check the paperwork. Siding and roofing warranties often restrict pressure and bleach-based cleaners.
- Check the age. Pre-1991 house with flaking paint: test for lead before any aggressive prep.
- Plan the next step. If you are painting or staining, ask your contractor how long surfaces need to dry before coating.
- Get it in writing. A written scope, price and what happens to plants and runoff.
Perspective from our crew
We repaint exteriors across the GTA, and we see the same pattern on jobs that failed before we arrived: someone blasted the wall with too much pressure, did not let it dry, and painted over it. The coating looked fine for a season and then peeled at the seams and window trim.
Our rule is simple. The wash is part of the paint job, not a separate errand. We choose the gentlest method that gets the surface clean, we protect plants and fixtures, we repair what we find, and we only coat once the substrate is dry. That prep is why our finishes are designed to last, and it is why we explain our prep and scope in a free, fixed estimate before any work starts.
If you are choosing between methods only to get ready for paint or stain, you do not need to become a cleaning expert. You need a contractor who treats prep as seriously as the final coat.
Enrico
What we do for GTA homes
If you are planning an exterior repaint, we handle prep, repairs and finish coats as one job, with premium materials, cleanup and a complimentary colour consultation. See our exterior painting service, or our deck and fence staining for wood that needs to be ready before winter. Budgeting? Our exterior painting cost guide walks through what drives a quote.
Want a clear scope and a fixed price? Request a free estimate and tell us what your house is clad in.
FAQ
Is soft wash worth the money?
For siding, stucco, wood and shingles, usually yes, because it treats the growth and avoids the damage high pressure can cause. Local published prices for a detached GTA house sit around $400 to $800, though your quote depends on size, height and access. Compare it against the cost of replacing damaged cladding, not against a cheap rinse.
How many PSI is considered soft wash?
Sources generally put soft washing under 500 PSI, with many placing it between 100 and 300 PSI. Pressure washing typically starts around 1,300 to 1,500 PSI and goes well above that. The cleaning solution, more than the number, is what defines the method.
How often should a house be soft washed?
Inspect the exterior once a year and clean only the areas that need it, as one siding manufacturer advises. A full soft wash makes sense when mould, algae or staining spreads, which happens sooner on shaded, damp sides of the house.
Can I pressure wash my house before painting?
Only on hard surfaces such as concrete. On siding, wood or stucco, a gentler wash is safer, and the wall must dry fully before coating. On a home built before 1991, check for lead paint first and do not scrape or sand it.
Do you rinse the roof after soft washing?
It depends on the contractor. Some leave the solution on asphalt shingles so the next rain rinses it, while the walls, glass and plants around the house are rinsed. Ask how they will handle each area before work begins.
Sources
- Pressure Washing vs. Soft Washing: Which Does My Home Need?
- What Is Soft Washing? How It Works
- Soft Wash vs. Pressure Wash: Choosing the Right Method
- Soft Wash vs Pressure Wash: What’s the Difference?
- What Is Facade Cleaning?
- CanExel Maintenance Guide
- Exterior Property Maintenance guide
- Health Canada: Chemical safety for DIY projects
- Health Canada: Chemicals and pollutants in the home
- Health Canada recall: RYOBI electric pressure washers
- Power & Pressure Washing Cost in Toronto
- Soft Washing vs Pressure Washing Canada Guide
- How to Soft Wash a Roof
