How to Pressure Wash a House

Written & researched by Elena Marsh Gardening & Landscaping Editor

Updated October 2026

Work in this order: cover the plants, apply house-wash detergent from the bottom up through the soap nozzle, let it dwell 5 to 10 minutes without drying, then rinse from the top down with a 40-degree tip at 1,300 to 1,600 PSI, always angling the stream slightly downward. That is the whole job. The detergent does the cleaning; the pressure only rinses. Almost every siding disaster comes from reversing that — using high pressure to compensate for skipping the chemistry.

The Right Pressure for Your Siding

Pressure washing a house is the one application where the big number on the box is actively dangerous. Siding is thin, it overlaps, and there is a wall cavity behind it. Match the pressure to the material and keep the wand well back.

If your machine has no pressure control — most consumer electrics do not — you control force with tip selection and distance instead. Going from a 25-degree tip to a 40-degree tip and stepping back a foot cuts the force on the wall dramatically. That is the adjustment you have.

Before You Pull the Trigger

Twenty minutes of preparation saves the two problems that ruin this job: dead landscaping and water inside the wall.

1. Wet down and cover plants. House-wash detergents kill foliage. Soak every shrub and bed within about ten feet of the wall with plain water first — saturated leaves absorb far less — then drape them with plastic sheeting or a tarp. Rinse everything again when you finish.
2. Close and check every window. Latched, not just shut. Check for failed glazing, gaps in caulk, and any storm window with a weep hole facing up.
3. Kill power to exterior outlets and fixtures. Switch off the relevant breaker, and cover outdoor receptacles, light fixtures, doorbells, cameras and the electrical meter with plastic and tape.
4. Cover the dryer vent, attic vents and any soffit vent you can reach. These are direct paths into the structure.
5. Walk the walls looking for loose siding, failed caulk and peeling paint. Anything already loose will come off, and the water will go where it came from. Fix it first or work around it at very low pressure.
6. Plan your footing. Wet siding, wet grass and a ladder are the actual injury risk on this job, well ahead of the machine.

Detergent Does the Work

The green and black staining on a shaded wall is living — algae, mildew and lichen. Blasting it with water removes the visible layer and leaves the organism, which is why houses cleaned with water alone look terrible again within a season. A proper house-wash detergent kills it.

Use a pressure-washer-rated house and siding cleaner such as Simple Green Oxy Solve House and Siding cleaner (paid link), or a sodium hypochlorite mix if you are comfortable with bleach chemistry and have protected the landscaping properly. Apply through the black soap nozzle — the widest, lowest-pressure tip, and the only one that lets the machine draw from the detergent tank at all, because the detergent siphon only opens at low pressure.

Apply from the bottom up. This is counterintuitive and it matters: detergent running down over dry siding leaves permanent-looking streaks, while detergent running down over already-wet siding does not. Rinse in the opposite direction, top down.

Let it dwell 5 to 10 minutes, and do not let it dry. Dwell time is where the cleaning happens. If the wall is in full sun and drying fast, work smaller sections and re-wet as needed. Never apply detergent to a hot, sun-baked wall in midday.

The Rinsing Technique

Now the pressure, and there is less of it involved than people expect.

Angle the stream downward. Lap siding sheds water the way shingles do. A stream angled upward goes behind the laps and into the wall cavity; a stream angled downward runs off the face. Hold the wand so the water hits at roughly 45 degrees, coming down.

Work top to bottom, in overlapping horizontal passes. Rinse a full section from the roofline down before moving sideways, so dirty runoff always lands on siding you have not cleaned yet.

Keep the wand moving. A stationary stream cuts. Sweep steadily and overlap each pass by about a third.

Stay off the trim. Window frames, door casings, vents, light fixtures and soffits all have seals that a pressure washer will beat. Rinse near them at longer range or wipe them by hand.

Do not spray under the soffit or into gable vents. That is a direct route into the attic.

Rinse the plants again as soon as you finish each side, before the detergent residue dries on them.

Reaching the Second Story

This is the part that separates a comfortable afternoon from a bad one. There are three approaches and only two of them are sensible.

A telescoping wand, from the ground. A 24-foot telescoping pressure washer wand (paid link) reaches most two-story walls with your feet planted. It is heavy and awkward — expect tired shoulders — but it keeps you off a ladder, and it lets you maintain the downward spray angle from below by using the curved end wand. This is the right answer for most homeowners.

Soft washing with a downstream injector or a hose-end applicator. Chemistry at low pressure, thrown high by volume rather than force. It is what professionals use on second stories and on anything delicate.

A ladder with a pressure washer in your hands. Do not. The reaction force from the wand is enough to push you off balance, and you cannot brace against it on a ladder. This is a genuinely common way people get hurt on this job.

Safety: The Injury Nobody Expects

Pressure washers send an estimated six thousand people a year to US emergency rooms, and roughly one in seven of those visits leads to hospitalization — figures drawn from the Consumer Product Safety Commission injury surveillance data, as reported in Consumer Reports' pressure washer safety alert.

The injury that matters most is the one that looks least serious. A high-pressure injection injury forces water, dirt and bacteria under the skin through a puncture that may be no bigger than a pinhole and may barely bleed. The clinical review of hand high-pressure injuries reports amputation rates of roughly 30 to 40 percent, driven largely by people waiting because the wound looked minor. It is a surgical emergency, not a first-aid-kit wound.

The practical rules: never steady the spray by putting a hand in front of the tip, never aim the wand at anyone, treat the red 0-degree tip as one you essentially never fit to a house, wear eye protection and closed shoes, and release pressure from the hose before disconnecting anything. If a jet breaks your skin, go to an emergency department and use the phrase "high-pressure injection injury".

The Five Mistakes That Cause Damage

• Spraying upward under the laps. The damage appears months later as staining, mold or soft sheathing. This is the big one.
• Using a narrow tip because the dirt is stubborn. If water alone is not shifting it, the answer is detergent and dwell time, not a 15-degree tip.
• Skipping the plant prep. House-wash chemistry kills foliage reliably. Wet, cover, rinse.
• Letting detergent dry on the wall. Streaks that need a second full wash to remove.
• Pressure washing a roof from a ladder to reach a gable. Roofs should not be pressure washed at all — see how to pressure wash a roof, which explains why the answer is soft washing.

What Machine You Need

Less than you would think. A standard electric machine at around 2,000 PSI and 1.76 GPM, throttled by a 40-degree tip and distance, is ideal for siding — and it is quieter, lighter and safer near a wall than a 3,400 PSI gas unit. Gas earns its place on driveways and acreage, not on siding. Our full field is in the best pressure washers, and the honest limits of battery machines for a job this size are covered in best cordless pressure washer.

On frequency: most homes need this every two to three years, not annually, and washing more often than the dirt warrants is its own kind of wear. See how often you should pressure wash your house.

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