How to pressure wash a house comes down to keeping high pressure off the house. Wash the siding with a house-wash cleaner, let it sit, and rinse it at low pressure with the wand level or angled down, never pointed up under the laps. Save the high pressure for concrete. Keep both hands on the wand and both feet on the ground, and soak the plants before any cleaner goes on. If the job needs a ladder, that is the point to hire it out.
What you need before you start
A pressure washer with a soap tip and a wide rinse tip. For siding, the widest spray and the lowest setting are the ones you will use.
A cleaner made for house washing, and your siding maker's care sheet. CertainTeed, for one, does not recommend power washing its vinyl at all, and tells owners with algae to ask their siding contractor for a cleaner.
A garden hose and a soft, long-handled brush. The Vinyl Siding Institute's installation manual cleans siding with exactly that, and warns that stiff bristles and abrasive cleaners change the gloss and leave the siding splotchy.
Eye protection and closed, rubber-soled shoes. Mississippi State University's safety guidance calls for both and rules out sandals.
A GFCI outlet for an electric machine. The CDC says to test the ground fault circuit interrupter before every use.
Tarps for delicate plants.
How to wash the siding, step by step
Soak the beds and shrubs with plain water first. Cover anything delicate. Historic New England's washing guide says to wet the ground and plants, cover them with a tarp, and flood any plant the cleaner touches with plenty of water.
Close the windows and doors, and keep the spray off the vents. CertainTeed warns against long or high-pressure rinsing of open ventilated areas, which means dryer vents and gable vents.
Mix the cleaner to the label and put it on at low pressure. The VSI manual says to wash a whole house from the bottom up, which keeps the wall from streaking.
Give it the time on the label. Work in the shade or on an overcast day, so the cleaner and the rinse water don't dry on the wall before you rinse.
Rinse at low pressure from a few feet back. Hold the wand level or angled down, and keep it moving. Aiming up drives water under the laps.
Rinse the plants again when you finish. Then rinse the windows, which will still need a proper cleaning.
Do the concrete last. Anything that washes off the walls lands on a slab you are about to clean.
The numbers worth knowing: a garden hose runs 40 to 60 psi, and Historic New England caps wood at 100 psi. For brick, the National Park Service's Preservation Brief 1 says to begin at 100 psi or below and work up only as needed, to 300 to 400 psi at the top end. In Northville, the city's historic district standards tell owners to use only the gentlest cleaning method possible on brick, such as a low-pressure water spray and soft natural-bristle brushes.
Safety that matters
Injection injuries
The jet from a pressure washer can puncture skin. The CDC warns that these wounds can look minor at first, that people put off treatment because of it, and that the delay raises the risk of infection, disability or amputation. Its advice is to get medical attention as soon as possible after any high-pressure spray wound. Never point the wand at yourself, another person or a pet, and never test the stream with a finger or a foot.
Keep a firm grip with both hands and your feet planted. Mississippi State's guidance notes that a two-handed grip and a solid stance keep the gun from kicking back if you lose control of the hose.
Ladders
Stay off the ladder with a wand in your hands. The Mississippi State newsletter points out that owner's manuals don't recommend spraying from a ladder, because a burst of pressure can throw you off balance. The wand pushes back when the trigger opens, and controlling it takes both hands, which leaves none for the ladder. Second-story walls are where a weekend job turns into a hire.
Carbon monoxide
A gas engine gives off carbon monoxide. The CDC says never to run a gasoline pressure washer in an enclosed space or less than 20 feet from any window, door or vent. Starting it in the garage breaks that rule.
Cleaner, plants and storm drains
The published recipes for mildew on siding use household bleach, and bleach hurts plants. Purdue Extension tells homeowners to keep its detergent and bleach solution off shrubs and grass, and never to mix bleach with ammonia or any cleaner that contains it.
Watch where the runoff goes. Oakland County's Water Resources Commissioner points out that storm drains carry water straight to the nearest lakes, rivers or streams without treating it, and asks residents to keep soapy water out of them.
What goes wrong
These are the mistakes that do lasting damage:
Water behind the siding. The VSI manual describes vinyl as a cladding with a water-resistive barrier behind it to stop water that gets past. A jet aimed up from the lawn pushes water under the laps and into the wall, where it is slow to dry.
Stripped paint and fuzzy wood. High pressure lifts paint off painted wood and older trim, and across the grain it raises the fibers so the wood dries rough. Historic New England lists water behind the boards and a raised grain among the risks.
Washed-out mortar. Old lime mortar erodes under a strong jet, and the National Park Service notes that eroded joints let more water into the wall.
Striped concrete. A wand held close leaves lighter and darker bands etched into the slab. A surface cleaner, which spins its nozzles at a fixed height, prevents them.
Empty paver joints. A jet pointed down into paver joints washes out the sand, and the pavers lose what keeps them tight.
Streaked aluminum. Chalky paint on aluminum siding comes off unevenly when it is scrubbed or blasted, and the wall dries patchy.
Burned plants and spotted glass. Cleaner left on leaves in hot sun burns them, and rinse water dries in spots on every window.
When to hire it out
Washing a one-story vinyl house from the ground with a cleaner and low pressure is a reasonable weekend job. Hire it out when:
The walls you need to reach are above the first floor.
The house has painted aluminum that chalks, which needs a test spot before anything else.
The brick is old, with soft lime mortar, as on the older streets of Northville and Plymouth.
The siding is cedar or rough-sawn wood panel, common on 1960s to 1980s houses in Farmington Hills.
The concrete is stamped, colored or already flaking.
The north wall went green again within months of the last rinse.
We soft wash siding at low pressure and clean concrete with a surface cleaner, from April to November, through our pressure washing and soft washing service. For how each surface is handled, read pressure washing vs soft washing. For what moves the price, read how much pressure washing costs.
Questions people ask
What psi should I use to wash my house?
Less than people expect. A garden hose runs 40 to 60 psi, and that is enough to rinse siding once a cleaner has done the work. Preservation guidance caps wood at 100 psi and starts brick at 100 psi or below, rising to 300 to 400 psi at the top. Save high pressure for concrete.
Can I use bleach to clean my siding?
Yes, diluted and with care. Purdue Extension's mildew recipe is household detergent, household bleach and warm water, and the vinyl siding manual adds laundry bleach to its wash for mildew. Soak nearby plants first, rinse the wall well, and never mix bleach with ammonia or a cleaner containing it. Check your siding maker's care sheet too.
Is it safe to pressure wash from a ladder?
No. The wand pushes back when the trigger opens, and controlling it takes both hands, which leaves none for the ladder. Safety guidance notes that owner's manuals don't recommend spraying from a ladder, because a burst of pressure can throw you off balance. Second-story walls are the point to hire it out.
What should I do if the spray hits my skin?
Get medical care as soon as possible, even if the wound looks small. The CDC warns that high-pressure spray wounds can be serious even when they look minor at first, and that waiting raises the risk of infection, disability or amputation. Call 911 if you need emergency help.
Get a quote
Glass Guru has been owner-operated in Northville since 2014, and we wash houses across ten towns on our pressure washing service areas page. If the job has outgrown a weekend, tell us the address and what needs washing, and we'll price it. Get a Free Quote
