House Washing Cost: What a Washington Quote Should Include

Washington publishes no price for washing a house. No state agency measures what homeowners here pay, and the figures that surface in a search come from quote-request websites and washing companies’ own marketing — a rate card is not a market measurement, and a lead-generation page is not a survey. What the state does publish is the rule that governs the work and the paperwork around it, and both decide what a quote should contain. The useful question is not what a house wash “costs” but whether the two bids in front of you describe the same job.

There is no rate to look up

The state publishes the rule, not a price. The pollution-prevention guidance distributed through Washington’s municipal stormwater programs opens with the mechanism — “Pressure washing can release pollutants from surfaces due to the force of the water” — and carries the instruction that decides most of the paperwork: “Regulations and laws about pressure washing can vary by location, and some jurisdictions strictly regulate pressure washing.” Where the route is uncertain, the guidance’s own answer is to check with the local jurisdiction.

Washington does not price even the washing it buys. The Department of Enterprise Services’ statewide janitorial contract, effective March 2024, carries window washing as one of its three categories and prices it as a percentage mark-up on the state’s prevailing-wage rate for window cleaners, county by county — an hourly rate rather than a figure for a job. The department’s own worked example turns a prevailing wage of $13.50 and a mark-up of 85 percent into $24.98 an hour. That is public-building glass under a purchasing structure, not a house on a residential street; it is here for one reason: a large buyer of exterior washing fixes no per-job price, because the unit of measure is a commercial choice, not a standard. What a homeowner can do instead is make two quotes describe the same work — a scope exercise before it is a money one.

What actually moves the number

The surfaces, and how they are measured. A house wash can mean the cladding, or the cladding plus the trim, soffit, window frames, a deck and a roof edge. Ask which faces are included and for the measured area of each; a total for an unpriced area is a total for an unknown job.

What the material permits, and the labour that follows. This is the cost driver most comparisons miss, because it is set by the manufacturers, not the crew. James Hardie’s cleaning bulletin for its fiber-cement siding allows a pressure washer only with wide fan tips kept at least six feet off the wall at pressures under 1,500 psi — a slower, more careful method — and notes that damage from improper cleaning may not be covered by the warranty. The Vinyl Siding Institute’s installation manual specifies an ordinary long-handled car-washing brush with soft bristles and warns against stiff brushes and abrasives. Two houses of the same size can therefore need two different methods, two different amounts of time and two different sets of equipment. A bidder who has not asked what your walls are made of is quoting a house they have not priced.

Water in. Ask who supplies the water and how it reaches the far end of the work. A spigot at the wrong end of the house, a hose run across a planting bed, and a filled tank on the truck are three different setups, and the quote should say which it assumes.

Water out — the line that most often differs. Washington’s guidance is to capture the wash water, cover or block nearby storm drains, and keep everything but rain out of them, because those drains reach the nearest creek, lake, wetland or Puget Sound. How far that goes depends on what is in the water. King County requires a business washing a building there to collect it with a sump pump, wet vacuum or similar device whenever any soap, detergent or other chemical is used, and forbids the water from reaching the storm drainage system, groundwater or surface water; runoff may go uncollected only where no chemicals are used, only cold water is used, no PCB-containing materials are present, and the water is diverted to vegetation or filtered through fabric, with the area swept first. So “cold water only” and “with a cleaner” are two different services, and a quote that names neither has not priced the job it is quoting. Two more lines in the same manual read as cost lines: wash water may not flow off the site at all, making the job contained work rather than a rinse toward the street; and where the surface carries lead or other heavy-metal-bearing paint or dust, the manual requires a commercial washing service that will collect, test and dispose of the water. Where the water may go once collected is the hardscape cluster’s subject.

Protection, access and the day. The Hardie bulletin directs that landscaping or vegetation be shielded during cleaning, and the vinyl manual’s instruction ends by telling the reader to protect shrubs from direct contact with cleaning agents. The state’s own exterior-washing specification goes further, requiring ground protection or matting whenever ladders or aerial lifts are used. Ask how the crew reaches a second storey, how plants, open windows and vehicles are protected, and what happens if the surface is worse than a photograph suggested; the state’s consumer guidance is that a change to the work, in material or scope, should be agreed in writing before it is done.

Three lines that are separate jobs

A roof is not a wall. The Asphalt Roofing Manufacturers Association is categorical that high-pressure washing systems are likely to damage asphalt roofing and should not be used to remove algae or for any other purpose, and recommends that only trained professionals work on a roof at all. Where a roof is washed, the county manual requires the rooftop downspouts to be blocked or disconnected first, with the water directed to vegetation, collected for the sanitary sewer, or hauled off-site.

Glass and gutters are their own specifications. Window washing is priced and specified separately from a building wash — the state contract above treats it as a category of its own, down to removing all moisture from sills and mullions — and what a gutter-cleaning scope contains is a checklist of its own. Ask which of the three the bid covers, and expect the answer in writing.

What the documents should say

Washington’s contractor-registration office publishes the cheapest quality control available to a homeowner. Its advice is to get bids in writing from several registered contractors and to judge scope, warranties, references, completion dates and price together, with the warning that “focusing only on price may get you a less than desirable result.” It lists a contract’s minimum contents: the price including sales tax; the payment terms; permit fees if applicable; the specific work to be performed; a list of materials, major suppliers and subcontractors; and the warranties and the process for change orders. A registration number must appear in all advertising and on the written bid, and the department’s Verify tool reports registration status, bonding, liability insurance and outstanding infractions.

Whether a washing job is the kind of work that requires that registration is the department’s answer to give, not this page’s; the state lists the work requiring it as altering, repairing, constructing, consulting or superintending, improving, moving, wrecking or demolishing, and publishes a route for asking about a specific business. Under RCW 18.27.114 a contractor must give a written Notice to Customer before starting a residential project whose bid is $1,000 or more, and that notice carries its own warnings — that the property may be liened, and that the customer may withhold a percentage of the contract. Whether a washing job falls inside that provision is, again, a question for the department rather than for a quote. The payment terms belong in the same conversation: pay as phases of the work are completed rather than on a calendar, withhold a portion until the work is complete and satisfactory, and keep a receipt for every payment. The state’s warning-sign list reads as a filter on a bid — a contractor who “does not provide a written contract or complete bid” is on it, alongside a special price that holds only if you sign today.

Reading two quotes as the same job

Next step

Ask two bidders for the same document, in the same order: the surfaces with their measured areas and the unit each is priced in; the water in and the water out; whether a cleaner is used and whether the water is cold; how plants, ground and openings are protected; what the minimum charge covers; what is excluded; and the registration number, completion date and payment terms. Then compare the answers rather than the totals.

Nothing here is a price, and none is published, because the number belongs to the house, the access and the local rules. What the owner settles before the crew arrives is the preparation page in this cluster, why the material and not the method comes first is the pillar, and reading two quotes across trades generally is its own subject.