Pressure washing, at the pressure your house can survive
Most of what needs cleaning on a house should never see high pressure. We match you with exterior cleaning pros who pick the method by substrate - and we tell you which surfaces the pressure washer is about to ruin.
What is pressure washing?
Pressure washing uses pressurised water - sometimes heated, usually with a detergent - to remove dirt, algae, mildew, moss and staining from exterior surfaces. The useful distinction is not how much pressure a machine can produce but how much a given surface can take. Hard, sound concrete tolerates a lot. Roofs, stucco, painted wood, older siding and soft or historic masonry tolerate very little, and are cleaned with chemistry and dwell time at low pressure instead.
How pressure washing actually works
Walk the property and identify substrates, not square footage
A competent contractor walks the whole exterior before quoting and names what each surface actually is: vinyl or fibre cement or aluminium or wood siding; poured concrete or pavers or exposed aggregate; brick, stone or stucco; asphalt shingle or tile. The plan is built per substrate.
Watch forA price quoted over the phone from a street-view image. Nobody can tell painted 1960s clapboard from fibre cement that way, and the pressure that is safe for one will destroy the other.
Choose the method for each surface
Broadly: hard flatwork gets high pressure through a rotating surface cleaner; walls, roofs and anything soft, painted or porous get a dilute cleaning solution applied at low pressure, left to dwell, then rinsed. Most residential jobs are a mix of both on the same property.
Watch forOne wand, one pressure setting, used on everything from the driveway to the shutters. That is the single most common way a cheap job turns into a repair bill.
Protect what is not being cleaned
Plants get soaked before and after so they cannot take up concentrated solution. Exterior outlets, light fixtures, security cameras and window air conditioners get covered. Doors and windows get checked for gaps, and vehicles get moved out of overspray range.
Watch forNobody wetting the landscaping. Sodium hypochlorite solutions will burn foliage, and the damage shows up two days later when the crew has gone.
Clean, dwell and rinse
On chemically-cleaned surfaces the solution is applied bottom-up, allowed to work for a few minutes, and rinsed top-down before it dries. On flatwork the surface cleaner is run in overlapping passes so the whole slab lightens evenly rather than in stripes.
Watch forSolution allowed to dry on the surface, which leaves a pale haze that is very hard to fix, and wand marks on concrete, which are permanent because the wand has removed the top layer of cement paste.
Final walk-round while the crew is still there
Look at the surfaces wet and, if you can, again once dry - some faults only appear dry. Check window glass for spotting, check that screens went back on, and check that the plants got rinsed.
Watch forA crew that packs up before you have walked it. Everything on this list is easy to fix in the first ten minutes and expensive to fix a week later.
What does pressure washing cost?
Exterior cleaning is usually priced per square foot for flatwork and as a flat package for a house wash, with the property walked first. Height, access, how far gone the growth is, and whether hot water is needed all move the number. The Cost Guide breaks the pricing structure down.
See the full pressure washing cost guide - by material, size and region →
If the number is the problem, here are the ways people pay for it →
HomeMatchup does not perform pressure washing. We match you with licensed local pressure washing pros for pressure washing. Free for homeowners — Get matched free · how we verify pros.
When pressure washing is the wrong call
When saying yes is the wrong move:
- The surface is failing, not dirty. Peeling paint, spalling concrete, rotten trim and crumbling mortar do not get better when washed - they get worse, and the wash reveals damage the dirt was hiding. Repair first, clean after.
- It is your roof. The Asphalt Roofing Manufacturers Association states plainly that a power washer should not be used on asphalt shingles, because the pressure strips the granules that protect the shingle. Roofs are treated chemically at low pressure, and that is a separate specialism.
- The masonry is historic or soft. The National Park Service recommends beginning at 100 psi or below and generally going no higher than 300-400 psi on historic masonry, because higher pressure etches soft stone and some brick. If your building is old, the pressure washer is the wrong tool.
- You have pre-1978 painted wood siding. Blasting paint off a house of that age can mean spreading lead-containing paint chips and dust across your garden. Test first, and treat it as a lead-safe job if positive.
- You want a stain, not dirt, removed. Rust, tannin bleed, oil and efflorescence are chemical problems with chemical answers. More pressure just etches the surface around a stain that stays where it is.
- Freezing weather is forecast. Masonry can hold water for days after washing. Washing into a freeze risks spalling and cracking as the trapped water expands.
Can I do this myself?
Reasonable to DIY
- Rinsing loose dirt and cobwebs off a sound concrete path or patio with a 25- or 40-degree tip, standing on the ground
- Cleaning a small area of sound flatwork with a rented surface cleaner, working in overlapping passes
- Washing garden furniture, bins and tools well away from the house and the planting
- Testing any new surface in an inconspicuous spot first, at the lowest pressure that does anything
Call a licensed pro
- Anything above ground-floor reach, anything on a roof, anything requiring a ladder
- Siding, stucco, painted wood and soft or historic masonry, where the method is chemical and the margin for error is small
- Pre-1978 painted surfaces where lead is a real possibility
- Rust, oil, tannin and efflorescence staining, which need the right chemistry rather than more pressure
- Anywhere runoff will reach a storm drain, a watercourse or a neighbour and you would be liable for it
What to check when hiring for pressure washing
- Which surfaces will you clean with pressure, and which chemically at low pressure? The whole quality question in one sentence. If the answer does not vary by substrate, the crew has one method and will use it on everything.
- What pressure will you use on my siding, and have you seen it up close? Siding is where water gets driven behind the cladding and into the wall. Consumer Reports warns specifically against spraying into gaps around doors, windows and under siding lap joints.
- How do you protect landscaping, and who pays if plants die? Plant damage is the most common complaint in this trade and it shows up days after payment. Get the answer before the truck arrives.
- Are you carrying general liability insurance, and can I see the certificate? The failure modes here - water inside a wall, a broken window, damaged paint - are expensive relative to the job. Ask for the certificate, not a verbal yes.
- Where does the runoff go, and do local rules restrict that? Wash water carrying detergent and biological growth into a storm drain is a regulated discharge in many jurisdictions. A professional operator knows their local rule; a weekend crew does not.
- What water and power are you using - mine or yours? Most crews use your outdoor spigot. Confirm it works, that it is not on a well with limited flow, and that this is agreed in advance rather than discovered on the day.
- What does the result actually look like, and how long before the growth returns? Nobody can make old concrete new. An honest contractor tells you what will and will not come out, and that algae returns on a cycle rather than being cured once.
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Sources
Sources last checked
- Water runoff and cleaning chemicalsU.S. Environmental Protection AgencyRetrieved 2026-08-04Stormwater discharge context when exterior cleaning enters drains.
- Occupational Employment and Wages — Construction TradesU.S. Bureau of Labor StatisticsRetrieved 2026-08-04Labor cost context for home-services trades nationally.
Sources for figures and claims on this page.
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