Pressure Washing · Service

Soft washing: killing the growth, not blasting it

The low-pressure chemical method used on everything a pressure washer would wreck. What is in the solution, what it does to the organism, why the green comes back — and how to hire someone who understands all three.

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In short

What is soft washing?

Soft washing cleans an exterior surface with a dilute cleaning solution applied at low pressure and given time to work, then rinsed off — instead of removing growth with mechanical force. It exists because the discolouration on most houses is living: algae, mildew, lichen and moss with roots into the surface. Pressure removes what is on top and leaves the organism behind. Chemistry kills it, which is why a soft wash both looks better and stays clean longer on the same wall.

The job

How soft washing actually works

Identify the organism, then the substrate

Algae, mildew, moss and lichen respond differently and sit differently on the surface. Lichen and moss are anchored and need longer contact; surface algae releases quickly. What the surface is made of then sets the concentration and the contact time that are safe.

Watch for: A quote given without anyone looking at the growth. Lichen on rendered masonry and a light algae film on vinyl are the same colour from the street and completely different jobs.
Dilute to the surface, not to the stain

Soft wash solutions are cleaning agents and surfactants mixed down with water. The surfactant is what makes the mix cling to a vertical surface long enough to work rather than running straight off. Concentration is set by what the substrate will tolerate.

Watch for: Mixing strong "because it is bad". Over-concentrated solution on painted wood, aged paint or aluminium can dull, streak or lift the finish, and there is no going back from that.
Soak the landscaping first

Every bed, shrub and lawn edge within reach of overspray and runoff is watered thoroughly before anything is applied. Saturated foliage and soil dilute what lands on them instead of drawing it up.

Watch for: A crew that only rinses plants afterwards. After is too late — the damage is done in the first minutes of contact.
Apply low, and let it dwell

Solution goes on at low pressure through a wide fan or a dedicated soft wash tip, bottom-up, and is left for a few minutes. Dwell time is the active ingredient of the whole method — this is where the organism is killed rather than displaced.

Watch for: Solution drying on the surface. On a hot sunny elevation it can dry before it has worked, leaving pale ghosting and an unkilled wall. Competent crews re-wet, or move to the shaded side and come back.
Rinse thoroughly and neutralise the surroundings

The rinse is top-down and continues until residue is gone, not until the surface looks clean. Planting and hard landscaping in the runoff path are rinsed again afterwards.

Watch for: A short rinse. Residue left behind is what causes the film on glass, the patchy screens and the plant damage that shows up two days later.

Money

What does soft washing cost?

Soft washing is usually quoted as part of a whole-surface package rather than by the hour, priced on area, access and how established the growth is. Heavy lichen and moss take more solution and more dwell and cost more than a light algae film. The Cost Guide sets out the pricing structure.

See the full soft washing cost guide — by material, size and region →

Exterior cleaning tools → Work out area and method before you take quotes.

Straight answer

When soft washing is the wrong call

Everyone else ranking for this is paid when you say yes. Here's when you shouldn't.

The problem is not alive. Rust bleed, tannin staining from overhanging trees, oil, efflorescence and artillery-fungus spotting are not organisms and a soft wash will not shift them. Each needs its own targeted treatment, and being told otherwise is the clearest sign of a contractor guessing.
It is your roof. Roof washing has different access, different risk and a different insurance profile, and it belongs to a dedicated roof cleaning trade. Have it quoted as a roof job by someone who does roofs, not added to a wall wash.
The coating is already failing. Soft washing does not have the force to strip sound paint, but it will finish off paint that is already peeling or blistering, and it will make heavily chalked paint look blotchy. If the finish is at the end of its life, this is a repaint, not a wash.
Your planting is precious and directly against the wall. Mature specimen shrubs, established ferns and anything in tight beds under the elevation being washed are genuinely at risk. If you would be devastated to lose them, either have them physically covered or accept that some elevations should be hand-cleaned instead.
You need it to be permanent. Nothing in exterior cleaning is. Soft washing extends the interval because it kills rather than displaces — it does not stop new spores landing on a damp, shaded wall.
Runoff has nowhere safe to go. On a property that drains straight to a watercourse, a bare storm drain or a neighbour's ground, containment or a different method has to be planned before work starts, not improvised on the day.

Your options

Types of soft washing

Soft washing vs high-pressure washing

The full side-by-side, with the surface matrix.

Roof cleaning

Roofs are soft washed too — by a different trade.

Common exterior staining

Identify what you are actually looking at first.

Compare pressure washing options side by side →

Before you sign

What to check when hiring for soft washing

What is in your solution, and at what dilution for my surface?

You are not testing them on chemistry — you are testing whether the dilution changes by substrate. A single answer for every surface means a single mix in the tank.
How long do you let it dwell, and what do you do on a hot sunny wall?

Dwell is the method. "We re-wet so it cannot dry, or we work that elevation in shade" is the answer of someone who has done this properly.
Do you carry a pesticide or applicator licence if my state requires one for this work?

Some jurisdictions regulate applying certain biocidal treatments to exterior surfaces. Requirements vary and the contractor should know their own state's position without hesitating.
What is your plant protection routine, before and after?

The correct answer includes pre-soaking. If they only mention rinsing afterwards, they have the sequence wrong and your beds will show it.
Will there be a smell, and how long does it last?

There usually is one during and shortly after the work. Being told in advance is the difference between a normal job and a panicked phone call.
What is your realistic expectation for lichen and moss on my surface?

Anchored growth sometimes leaves a shadow after the organism is dead and needs a second visit or simply time to weather off. Get that expectation set before, not after.
How long before this needs doing again on a house like mine?

A local operator who has cleaned comparable properties for years can answer this specifically. A vague "a few years" means they have not been back to look.

All pressure washing hiring checklists →

Local pros

Soft Washing near you

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Related work

Often done at the same time

House Washing

The soft wash method, sold as a whole-house visit

Pressure Washing

Where mechanical force is still the right answer

Brick & Masonry Cleaning

Growth on masonry, and its pressure limits

Driveway Cleaning

Flatwork, where the method flips

All pressure washing services →

FAQ

Soft Washing — questions people ask

Still have a question? Talk to our team →

What is actually in a soft wash solution?

Broadly a cleaning agent, water, and a surfactant that makes the mix cling to a vertical surface rather than running off. Published concentrations vary widely between contractors and none of the manufacturer or trade bodies we could verify publish a single authoritative recipe — the Asphalt Roofing Manufacturers Association, for example, explicitly notes that mixing directions vary between manufacturers. Ask your contractor what they use and at what dilution for your specific surface, and check it against your cladding or coating manufacturer's own care guidance.

Why does soft washing keep the surface clean longer?

Because it kills the organism rather than removing the visible part of it. Pressure blasts off the growth that has already spread across the surface while leaving the root structure in the pores and texture, so it regrows from an established base. Killing it means regrowth has to start from new spores landing on the surface, which takes considerably longer.

Is soft washing safe for painted surfaces?

Sound paint in reasonable condition normally cleans without harm, which is much of the point of the method. The failure cases are paint that is already chalking, blistering or peeling, and over-concentrated solution left to sit on a hot surface. Ask for a test patch somewhere inconspicuous on any painted elevation you care about — a contractor who resists doing one is telling you something.

Does the bleach smell go away?

Yes, and generally within hours of a thorough rinse. It is strongest during application and while the surface is still wet. Close the windows before the crew starts, keep pets indoors during the work and for a little while after, and be aware that a still, humid day holds the smell around the house longer than a breezy one.

Can I soft wash my own house with a garden sprayer?

You can clean small, reachable areas that way, and people do. What you will not replicate is the reach without a ladder, the consistent dilution across a whole elevation, and the volume of rinse water needed to clear residue properly. Reach and rinse are the two things amateurs get wrong, and an under-rinsed wall streaks visibly once it dries.

Is "no-pressure washing" a different service?

No — it is a marketing name for the same method. Nothing is applied at literally zero pressure; the solution still has to be projected at the wall. What the phrase is signalling is that the surface will not be subjected to mechanical force. Judge the contractor on dilution, dwell and plant protection, not on which of the trade names they have put on the van.