Can you pressure wash stucco?

Not at real pressure. Stucco is a drainage cladding with a sand-and-cement finish coat, and a tight jet at close range both breaks that finish apart and drives water past the control joints and weep screed into the wall assembly, where it does not dry. Stucco is cleaned with a low-pressure application of a cleaning solution that kills the growth, followed by a rinse — the same method used on a roof, and for the same reason.

Is pressure washing a roof a bad idea?

Yes, on every common roof type. The mineral granules on a composition shingle are its ultraviolet protection, pressure strips them, and most manufacturers exclude pressure washing from the warranty on that basis. On tile, the waterproofing is the underlayment beneath the tile, and driving water up under the tiles puts it where the roof has no path for it — plus tile breaks underfoot. Roofs are soft washed, worked from the edge or a lift where the layout allows.

How often should I pressure wash my driveway?

About once a year for most Los Angeles driveways. Sooner if it sits under a tree that drops sap or honeydew, if a sprinkler hits it, or if it is shaded and stays damp — those can want cleaning twice a year. A sealed driveway holds its look longer between washes, which is part of what you are paying for when you seal one.

What causes stripes on concrete after pressure washing?

An uneven pass with a bare wand. The jet cleans a narrow band, and where passes overlap the concrete is cleaned twice and eroded slightly more, so you get light and dark bands the length of the run. The stripes are in the concrete surface, not in the dirt, so re-washing does not remove them — evening them out means taking the whole surface down to match, or resurfacing. A spinning surface cleaner attachment holds a fixed height and overlap, which is how the problem is avoided in the first place.

Will pressure washing damage my paint?

Sound paint on a sound substrate survives a low-pressure wash. Paint that is already failing — chalking, hairline cracking, lifting at the edges — will come off, and it will come off in a patch that then needs repainting. That is worth knowing rather than fearing: if a gentle wash takes the paint off, that paint had already let go and was going to fail on its own schedule. What you do not want is high pressure deciding that for you across an entire elevation.

Do I need to seal my concrete after pressure washing?

Not on a plain broom-finished driveway unless you want the stain resistance. It is worth it on pavers, on stamped or coloured concrete where the colour is a surface layer, and on porous concrete that takes oil drips. Two rules either way: never seal a surface that has not fully dried, because trapped moisture makes the sealer cloud and peel, and never seal over organic growth that was blasted off rather than killed. Sealing is also a maintenance cycle, not a one-time upgrade.

Pressure washing vs soft washing: which your surface needs

One removes what is stuck on. The other kills what is growing. Choose wrong and you pay twice — once for the wash, once for the repair.

August 6, 2026 · 7 min read

From the sidewalk the two services look identical: a truck, a hose, a wand, a clean house at the end of the day. They are not the same job, they are not good for the same surfaces, and the difference is the single thing most likely to cost you money on an exterior cleaning.

Force versus chemistry

Pressure washing cleans mechanically. Water leaves the nozzle hard enough to lift what is stuck to a surface — dirt ground into concrete, tyre marks, dried mud, algae film, oil that has not yet soaked in. The water is the tool. Nothing about it is selective: it removes whatever is weaker than the jet, including the surface itself if the surface is weaker.

Soft washing cleans chemically. A cleaning solution is applied at roughly garden-hose pressure, left to dwell, then rinsed. The solution kills the organic growth — algae, mildew, mould, lichen — and the rinse carries off what is left. The water only delivers and removes. The cleaning is done by the chemistry.

The rule that follows from that: if the problem is stuck on, pressure is the right tool. If the problem is alive and growing, chemistry is. Most exterior staining in Los Angeles is the second kind, on surfaces that cannot take the first.

Which surface takes which

Takes real pressure

Broom-finished concrete driveways, walkways and patios that are sound and unsealed.
Unsealed brick, block and concrete masonry with mortar in good condition.
Concrete pavers, with the caveat that pressure lifts the joint sand and it has to be replaced afterwards.
Sound natural stone hardscape — flagstone, slate — at moderate pressure and never at close range on a soft stone.

Even here, condition governs. Concrete that is already spalling, popping aggregate or crumbling at the edges has lost its surface paste, and pressure takes more of it away. Old lime-rich mortar between bricks is softer than the brick and will wash out of the joint before the brick looks any cleaner.

Does not take real pressure

Stucco — the most common wrong call in Los Angeles, and the most expensive.
Painted wood siding, fibre cement and trim, particularly anywhere the paint is already chalking or lifting.
Composition shingle and tile roofing, in every case.
Wood decks and fences, including composite decking.
Painted, stained, stamped or sealed concrete — the colour and the coating are a surface layer, and pressure takes surface layers.
Window frames and seals, screens, weatherstripping, light fixtures, outdoor outlets, attic and dryer vents.

Stucco deserves the explanation, because it is not obvious why a wall made of cement is fragile. Stucco is a cladding, not a waterproof shell. It sheds most water and lets the rest drain down a plane behind it and back out at the weep screed. The finish coat is sand held in a cement matrix, and a tight jet at close range breaks that matrix apart — you get a lightened, sandy patch where the texture used to be, which no amount of later cleaning brings back. Worse, the jet drives water through the control joints, around window flashing and past the screed, into a wall assembly built to drain a trickle and not a stream. That water does not dry. It shows up weeks later as a stain on the inside of the drywall, and by then nobody connects it to the wash.

Roofs deserve it too. On a composition shingle, the mineral granules on the surface are the ultraviolet protection for the asphalt underneath — they are the reason the shingle has a service life. Pressure removes them, quickly and invisibly if you are standing on the ground, and manufacturers generally exclude pressure washing from their warranty for exactly that reason. On tile, the tile itself may survive the water, but the waterproofing on a tile roof is the underlayment beneath it, and driving water uphill under tiles puts it where the roof has no plan for it. Tile also breaks under the weight of the person walking it. A roof is a soft-wash job, worked from the edge or from a lift wherever that is possible.

Wood is the quiet one. Pressure does not just clean a deck or a fence, it carves out the soft spring wood between the harder grain lines and raises the grain, so the board comes out furry and rough and drinks stain unevenly forever after. Wood cleans with a low-pressure application of a wood cleaner and a rinse, and it is sanded, not blasted, if it needs to be smooth.

Why soft washing lasts longer

Black streaks on a north wall and green film on a shaded patio are living things, and they are not sitting on top of the surface. The root structure is down in the pores. Pressure removes the visible layer and leaves the roots, which is why a pressure-only clean on organic growth looks perfect on day one and is back within a few months — faster on a wall that stays damp.

A soft wash kills what is in the pores. Growth that returns has to arrive fresh as a spore and start over, which takes far longer. On organic staining that is the entire argument: you are not paying for a better-looking day one, you are paying for a longer gap before the next wash.

What is actually staining your house in LA

Nearly every exterior stain in Greater Los Angeles traces back to water landing somewhere it was not meant to, or to something dripping out of a tree.

Irrigation overspray. A sprinkler head hitting a stucco wall two or three mornings a week keeps that wall damp on a schedule, which is all algae needs. It is the single most common cause we find.
Rust streaks from sprinkler water. Well and reclaimed water in parts of the basin carries iron, and iron on stucco or concrete leaves an orange stain that is a mineral deposit, not dirt — it needs a rust-specific treatment, not more pressure.
North-facing shade. North walls, anything under a deep eave and anything behind a hedge dry slowly and grow first. On most houses the north side is visibly darker than the south side.
Tree drip. Aphids feeding on a ficus, jacaranda or carob excrete honeydew, black sooty mould grows on the honeydew, and it lands on whatever is beneath the canopy — usually the driveway and the car.
Marine layer. In the coastal and westside cities everything stays wet until mid-morning most of the year, which extends the damp hours the same way overspray does.
Dry-season dust bonded by the first rain of the season, which is why so many houses look worst in November.

Any of these that you can fix, fix. Turning one sprinkler head or lifting one branch changes how often you buy this service. Cleaning a wall that gets watered three times a week is a subscription.

What it costs

Exterior cleaning is priced by area. Three sizes that cover most of what people ask for — a two-car driveway, that driveway plus the front walkway and a back patio, and the wall area of a single-storey house exterior.

Project size	Typical range	Most land near
600 sqft	$315–$334	$324
1,500 sqft	$496–$525	$510
2,800 sqft	$646–$684	$665

Flat, ground-level surfaces with no sealer applied afterwards. A house exterior, a roof, a second or third storey, and sealing are all priced higher — the wizard asks and the number moves. Priced by the DPOC engine at the moment this page was built — the same engine that quotes your job. It is an instant estimate, not a final contract.

The surface question is the one that moves the price most, and it is also the one that decides whether the job should happen at all. Answer it honestly. A crew arriving expecting a driveway and finding a two-storey stucco elevation is a crew that either reprices on your doorstep or rushes.

What a bad job looks like afterwards

Walk the property the same day, in daylight, before anything dries into an excuse. These are the marks of a wash that was done with too much pressure or too little care.

Zebra stripes on concrete — light and dark bands running the length of the pass. That is not streaked dirt, it is concrete eroded unevenly where the wand overlapped and where it did not. It does not wash out; it grows out only if the whole surface is taken down to match, or resurfaced.
Exposed aggregate where there was none — the cream layer stripped off, sand and stone showing, the surface rough underfoot.
A sandy, lightened patch on stucco where the texture is flattened or missing.
Paint lifting at edges, at trim, around window casings and at the bottom course of siding.
Water stains appearing on interior drywall at window heads and ceiling corners in the days after — water went in behind the cladding.
Mortar washed out of brick or block joints, or joint sand gone from between pavers so the pavers rock underfoot.
Roof granules collected at the downspout outlet or in the gutter after a roof was cleaned.
Torn screens, water inside exterior light fixtures or outlets, damaged weatherstripping.
Burned or stripped plants along the wall line, which means the beds were not pre-wet, covered and rinsed.

Photograph anything you find the same day, with the date on the file, and raise it before the crew leaves the area. A damage claim made two weeks later against a stain nobody documented is a hard conversation for everyone.

Where the water goes

Storm drains in Los Angeles County run to the ocean, not to a treatment plant. The region's stormwater rules treat wash water carrying detergent, biocide, degreaser, oil or paint chips as a discharge rather than as rain, and putting it down a street drain is a problem — for the crew that did it and for the property it came from.

A competent crew has an answer for this before they start. On a heavy degrease they contain and recover the water rather than letting it run. On a light residential wash they keep it out of the gutter and direct it to landscape that can take it, and they block the inlet if the grade sends water that way. Ask. A crew that has never thought about it is telling you something about the rest of their process.

Plants are the same conversation. Pre-wet the beds so the foliage cannot take up solution, cover what is directly under the work, rinse thoroughly afterwards. That is the whole method, and it is the first step dropped by anyone in a hurry.

Sealing afterwards — worth it, and not

Sealing is worth paying for on pavers, where it stabilises the joint sand, keeps weeds and ants out of the joints and holds the colour; on decorative, stamped or coloured concrete, where the colour is a thin surface layer worth protecting; on porous concrete in front of a garage that takes regular oil drips; and on natural stone that stains.

It is an upsell on a plain broom-finished driveway you are content to have look grey, and it is a bad idea on any surface that has not fully dried — a sealer over trapped moisture clouds, blisters and peels, and the fix is stripping it. It is also a bad idea over organic growth that was blasted rather than killed, because you are sealing something living under a film. And it is a commitment: a sealed surface has to be re-sealed on a cycle, so it is maintenance you are signing up for, not a one-time upgrade. In our wizard the sealer is a separate question, so you can see the job priced with it and without before you decide.

What to ask before they start

What surface do you think this is, and what pressure will you use on it? The answer should change from surface to surface. One setting for the whole property means nobody is adjusting anything.
Is this a pressure clean or a chemical clean? On algae, mould or black streaking the honest answer starts with chemistry.
What are you applying, and how long does it dwell before the rinse? They should be able to name the product and produce the label or the safety data sheet.
What happens to the runoff? A real answer mentions the storm drain without being prompted.
What are you doing about the plants? Pre-wet, cover, rinse. If that is news to them, it will be news to your hedge too.
What are you not going to clean, and why not? A crew that tells you the roof is out of scope, or that the grey on the north wall is in the coating rather than on it, is the crew worth hiring.
Is the scope in writing, surface by surface, with before and after photos?

One more that is worth asking of anybody, not just of us: who is on the hook if the wash damages something. DPOC holds CSLB #999194. Every job runs under this licence — ours, not a subcontractor's — so your contract and your recourse sit with one licensed, insured company rather than with whoever happened to be holding the wand that morning.

The rental option, honestly

A rented machine will clean a plain concrete driveway, and there is no reason to pretend otherwise. The thing that decides whether it comes out well is the attachment. A surface cleaner — the round hooded head that spins two nozzles at a fixed height — is what prevents striping, because the height and the overlap stop depending on your wrist. The bare wand is what makes zebra stripes, and it makes them in the first twenty minutes while you are still learning the tool.

Where the rental goes wrong is when the driveway finishes early and the machine is still on the truck. The house, the roof and the deck are exactly the surfaces that punish pressure, and they are the ones reached from a ladder — where the recoil of the wand is what puts people on the ground. The wand itself is not a hose: at close range it can inject water and debris under the skin, which is an emergency room visit rather than a plaster.

Run the honest comparison on a small flat job: a day's machine rental, the surface cleaner, a degreaser, the fuel to fetch it and your Saturday. The gap against a crew is narrower than it looks, and it closes entirely the moment the job includes anything vertical.

The short version

Stuck-on grime on sound, unsealed concrete or masonry → pressure, with a surface cleaner rather than a bare wand.
Anything alive — algae, mould, mildew, lichen, black streaking → soft wash, so it does not come back by spring.
Stucco, painted siding, wood, roofing, anything sealed or coated → soft wash, no exceptions worth taking.
Fix the cause — the sprinkler head, the overhanging branch — or you are buying this on a schedule.

Common questions

Can you pressure wash stucco?: Not at real pressure. Stucco is a drainage cladding with a sand-and-cement finish coat, and a tight jet at close range both breaks that finish apart and drives water past the control joints and weep screed into the wall assembly, where it does not dry. Stucco is cleaned with a low-pressure application of a cleaning solution that kills the growth, followed by a rinse — the same method used on a roof, and for the same reason.
Is pressure washing a roof a bad idea?: Yes, on every common roof type. The mineral granules on a composition shingle are its ultraviolet protection, pressure strips them, and most manufacturers exclude pressure washing from the warranty on that basis. On tile, the waterproofing is the underlayment beneath the tile, and driving water up under the tiles puts it where the roof has no path for it — plus tile breaks underfoot. Roofs are soft washed, worked from the edge or a lift where the layout allows.
How often should I pressure wash my driveway?: About once a year for most Los Angeles driveways. Sooner if it sits under a tree that drops sap or honeydew, if a sprinkler hits it, or if it is shaded and stays damp — those can want cleaning twice a year. A sealed driveway holds its look longer between washes, which is part of what you are paying for when you seal one.
What causes stripes on concrete after pressure washing?: An uneven pass with a bare wand. The jet cleans a narrow band, and where passes overlap the concrete is cleaned twice and eroded slightly more, so you get light and dark bands the length of the run. The stripes are in the concrete surface, not in the dirt, so re-washing does not remove them — evening them out means taking the whole surface down to match, or resurfacing. A spinning surface cleaner attachment holds a fixed height and overlap, which is how the problem is avoided in the first place.
Will pressure washing damage my paint?: Sound paint on a sound substrate survives a low-pressure wash. Paint that is already failing — chalking, hairline cracking, lifting at the edges — will come off, and it will come off in a patch that then needs repainting. That is worth knowing rather than fearing: if a gentle wash takes the paint off, that paint had already let go and was going to fail on its own schedule. What you do not want is high pressure deciding that for you across an entire elevation.
Do I need to seal my concrete after pressure washing?: Not on a plain broom-finished driveway unless you want the stain resistance. It is worth it on pavers, on stamped or coloured concrete where the colour is a surface layer, and on porous concrete that takes oil drips. Two rules either way: never seal a surface that has not fully dried, because trapped moisture makes the sealer cloud and peel, and never seal over organic growth that was blasted off rather than killed. Sealing is also a maintenance cycle, not a one-time upgrade.