Residential Exterior Pressure Washing

Purpose

Pressure is not the cleaning lever. Chemistry, dwell time and rinse do the work on a house wash, and the pressure setting is a damage budget you spend. Turn it up and you drive water under laps and into window seals, fur softwood, strip paint that was not going to fail this decade, and cut mortar out of a joint. The customer sees a clean wall on the day and a leak or a chalked stripe next season.

The other reason this exists is that a pressure washer is the most dangerous tool a handyman owns and does not look like one. A stream that will not break skin at arm's length will inject at six inches, and the injury looks like a pinhole for the first hour.

Scope

Covers exterior cleaning of a residential or small commercial building and its flatwork: siding, trim, soffit, fence, deck, driveway, walk and patio, by pressure washing or low-pressure soft washing.

Does not cover roof surfaces or work from the roof plane, paint preparation for a coating system, mold remediation inside the envelope, or a wall step 1 finds presumed asbestos-cement or pre-1978 painted. Gutter interiors belong to the gutter cleaning SOP, and siding repair the wash exposes to the siding and trim patch SOP.

Roles and responsibilities

Procedure

1. Survey the building and close the gates before the machine comes off the trailer. Walk all four elevations and note cladding and build year, failed or open joints, damaged glazing, every exterior electrical device, the meter and service entrance, plantings, and where runoff will go. Acceptance: a line per elevation naming the cladding, the electrical devices present and the runoff path, plus the build year on the ticket. Wrong looks like starting on the dirtiest wall and meeting the service entrance halfway through. Stop rule: brittle, dense, wood-grain-free cladding of asbestos-cement era is presumed asbestos-containing and is not washed at any pressure, because blasting it with water is a disturbance; pre-1978 painted surfaces where the wash will remove coating route to the shop's pre-1978 procedure; and runoff carrying detergent or biocide toward a storm drain stops the job until the local stormwater authority's rules are checked, since those vary by municipality. Hazard: none at this step, a walk-around with a clipboard, provided no hose or cord is trailed across the route yet.

2. Isolate and protect, and write down every isolation so it gets undone. Open the branch breakers feeding exterior receptacles and fixtures on the elevations being washed, cover and tape those devices plus the meter, panel, air conditioner disconnect and any low-voltage transformer, latch every window and door, and pre-wet plantings. Acceptance: an isolate list with a line per item, every covered device photographed, and every plant in the spray zone soaked to runoff before any chemical is mixed. Wrong looks like bagging a fixture whose circuit is still hot, which holds water against an energized device instead of away from it. Stop rule: a receptacle or fixture whose circuit cannot be identified at the panel is not washed within a body length, and goes on the isolate list as declined with the reason. Hazard: water plus electricity is the killing combination here, so nothing gets wetted until its circuit is open at the breaker, and a device soaked anyway leaves the circuit open, untouched, and routed to an electrician; work practices for those circuits are 29 CFR 1910.333(b)(2) for general industry, with 29 CFR 1926.417 on construction.

3. Set the machine and prove the setting on a test patch, not on the wall. Pick the widest tip that will do the work, start at the lowest pressure and greatest standoff you think can work, and run a patch about a hand square in an inconspicuous spot on each distinct material. Acceptance: for each material, tip angle, pressure and standoff written down, and a patch that comes clean with no raised grain, no chalk streak, no mortar loss and no water pushed behind a lap, at or under the maximum in the cladding manufacturer's care instructions where they publish one, since exceeding it can void the warranty. Wrong looks like a zero-degree tip on siding, which is a cutting tool. Stop rule: a patch that marks the surface drops one step in pressure and adds standoff and re-tests once; a second marked patch ends pressure washing on that material and the job becomes a soft wash at low pressure with the chemistry doing the work, or it is declined. Hazard: the stream injects, so the wand is never pointed at a person or your own hand, the trigger lock goes on whenever you reposition, and washing runs from the ground with an extension wand rather than from a ladder, because the reaction force pushes the ladder out from under you; anyone struck goes to an emergency department immediately and says the words high-pressure injection injury, whatever the skin looks like, because a painless pinhole is still a surgical emergency.

4. Mix and apply the cleaning solution to the label, and keep it wet for the whole dwell. Read the product label, mix at the rate it states for the surface in hand, apply at low pressure bottom to top so runs do not streak dry material, and re-wet before any area dries. Acceptance: product name, label dilution and dwell time on the ticket, and the treated area visibly wet for the entire dwell. Wrong looks like a strong batch left to dry on hot siding, which etches a shadow of exactly the area you treated. Stop rule: a product whose label directions cannot be followed on this site, including any required personal protective equipment the shop does not have, is not used, because a product making a mold, mildew or algae claim is a registered pesticide and its label directions are enforceable, so using it another way is use inconsistent with the labeling. Hazard: sodium hypochlorite injures by contact, by ingestion and by inhalation of the mist, so each gets its own control: eye and face protection with chemical-resistant gloves and sleeves, no eating or drinking on the job, and application from upwind at low pressure. It is never mixed with an acidic masonry cleaner or an ammonia product, because that releases chlorine gas; if a mix happens everyone leaves upwind immediately and nobody returns to look, and solution in an eye is irrigated for the time the label states with the person then sent for medical care, label in hand.

5. Rinse to a plan, from the right direction and the proven distance. Rinse each elevation top to bottom in overlapping passes at the settings proven at step 3, keeping the stream roughly perpendicular to lap siding at eye level rather than angled up under the laps, and flush plantings and hardscape as you go. Acceptance: no solution left on any surface at the end of the elevation, plants rinsed within five minutes of last chemical contact, and one opening per elevation checked dry from inside. Wrong looks like rinsing from below, which drives water behind every course and into the wall. Stop rule: water appearing inside at any opening stops the elevation, the wall is left to dry, and the finding routes to the siding and trim patch SOP as a sealing or flashing defect rather than being washed past. Hazard: wet flatwork is the slip half of this job, so the hose stays out of the walking path and the tech works out of the runoff rather than standing in it; hearing protection goes on near a running gas machine, whose exhaust also means it never runs in a garage, breezeway or under a soffit where carbon monoxide collects.

6. Restore every isolation, prove the protection works, and close out on the record. Uncover each device on the isolate list, dry the covers before removing them so nothing drips into an enclosure, re-close the breakers, then test each exterior receptacle and protected circuit. Acceptance: restore list matching the isolate list one to one, every covered device uncovered and dry, each GFCI-protected exterior receptacle tripping on its own test button and resetting and confirming tripped with a plug-in tester, and every exterior fixture switched on and observed. Wrong looks like a breaker left open and found in the dark, or a cover taped on an outlet that is back on. Stop rule: a GFCI that will not reset, or that resets but will not trip on test, means water in the device or the circuit, so the breaker stays open, the receptacle is tagged, the customer is told in writing, and it goes to an electrician the same day. Hazard: this is the step that puts energy back with the family standing there, so stand to the hinge side of the panel rather than square in front when closing a breaker, and never close one onto a circuit whose devices are still covered.

The record this produces

Cladding and build year per elevation, the isolate list with its matching restore list, the test patch per material with tip angle, pressure and standoff, the manufacturer maximum where one was published, the product name with its label dilution and dwell, any elevation downgraded to soft wash, plant pre-wet and rinse times, the GFCI result per receptacle, and any opening that leaked.

The office reads the test patch line when a customer reports damage, because a documented setting on an inconspicuous patch is what separates a wash from a claim. The next tech reads the downgrade line so nobody re-learns the wall the hard way.

Worked pass: 1970s two-story, cedar lap on three elevations, brick on the fourth

Step 1: cedar lap, built 1974, so any coating is presumed lead-based where washing would remove it. The cedar is bare and weathered on all three elevations, so the paint gate did not fire, and the tech recorded that rather than assuming it. Six exterior devices, two fixtures, meter on the east wall, runoff to lawn with no storm drain in the path.

Step 2: isolate list carried nine items: two branch breakers open, six devices bagged and taped, one meter covered, all photographed. Plantings on the south wall soaked to runoff.

Step 3 FAILED and took its stop rule. First patch on the cedar: 40 degree tip, 1,200 psi, 12 in standoff. It cleaned but raised the grain, visible once dry, failing the no-raised-grain criterion. Under the stop rule the tech dropped pressure, added standoff and re-tested once at 40 degree, 600 psi, 24 in, and that patch still furred. A second marked patch ends pressure washing on that material, so all three cedar elevations became a soft wash, chemistry carrying the load and the rinse held under the pressure of the last failing patch. Brick tested clean at 40 degree, 1,200 psi, 18 in with no mortar loss, so that elevation stayed a pressure wash. Both settings went on the ticket.

Step 4: label read on site, mixed at the dilution it gives for weathered wood siding, applied bottom to top at low pressure. Dry-back in the sun timed at 4 minutes against a label dwell of 8 minutes, so 8 divided by 4 is two applications, meaning one re-mist at the 4 minute mark to stay wet for the full dwell.

Step 5: rinsed top to bottom, stream at eye level and perpendicular to the laps, plants rinsed within five minutes of last chemical contact, one window per elevation dry from inside. Step 6: restore list matched the isolate list at nine of nine, covers dried before removal, both breakers closed from the hinge side of the panel, all six receptacles tripped on their own test buttons, reset and confirmed tripped with a plug-in tester, both fixtures switched on and observed.

References

• The cladding, decking and masonry manufacturers' care instructions, which set the maximum pressure and the products permitted, and can void a warranty when exceeded
• The cleaning product's label, enforceable for any product carrying a pesticidal mold, mildew or algae claim, which owns dilution, dwell, protective equipment and first aid
• 29 CFR 1910.333(b)(2) for general industry electrical work practices, with 29 CFR 1926.417 on construction, for opening and restoring the circuits at steps 2 and 6
• Your municipality's stormwater authority for whether wash water carrying detergent or biocide may reach a storm drain, which varies locally
• See related: Gutter Cleaning and Minor Repair Visit; Siding and Trim Patch Repair; Deck Board and Railing Repair Standard