Should you pressure wash before painting or staining your house?
Updated · KeystoneProGuide editorial team
Should a house be washed before it is painted?
If there is mold or mildew on it, yes. The U.S. Environmental Protection Agency (EPA) says not to paint or caulk moldy surfaces: clean up the mold and dry the surfaces first, because paint applied over moldy surfaces is likely to peel. Its guidance for hard surfaces is to scrub the mold off with detergent and water and dry them completely.
How the cleaning is done, and what follows it, depends on the house. Three things can change the plan: the age of the paint, the material being coated, and, in Philadelphia, whether the house is on the historic register.
What if the house was built before 1978?
Then washing and preparing painted surfaces fall under the EPA's lead rule when a company is paid to do them. The EPA requires anyone paid to disturb painted surfaces in a pre-1978 home to be certified in lead-safe work practices, and says any renovation, repair or painting project in such a home that has lead-based paint can easily create dangerous lead dust.
Washing is part of that. The EPA's archived answer says pressure washing is allowed under the rule but subject to the same containment as other work, so that no dust or debris, including in the waste water, leaves the work area. If the same company will wash, scrape and paint, ask how it will contain each step. If you are doing the preparation yourself, the EPA's lead-safe practices for do-it-yourselfers include testing or assuming lead is present, containing the area, keeping dust down and collecting the waste, dirty water included.
How long should surfaces dry before a coat goes on?
The sources give a figure only for decks. A Forest Products Laboratory chemist said a cleaned deck should dry for at least one day in the sun, that two to three days are probably better, and that you can easily wait two to three weeks before adding a finish. He also said warmer weather helps penetrating finishes work better. For siding and trim, follow the paint or stain maker's instructions; no source read for this guide gives a drying time.
Does the deck need cleaning before it is stained?
Yes. The same chemist said that before refinishing a deck you first must clean it, and warned that aggressive scrubbing or a power sprayer can damage the surface in a way that later makes it hard for an absorbing finish to work. His advice was to let a cleaner do the work and rinse with a garden hose. Cleaning a wood deck before staining sets out his method.
Should vinyl siding be painted after washing?
Check with the maker first. The vinyl siding industry's association, PEPA, says painting vinyl is often unnecessary because its color is designed to last, and that painting it could void the product warranty. It also says to cover siding when staining a nearby deck or sealing a driveway, so the new coating does not stain it.
What about brick or stone?
The sources treat cleaning and coating masonry with care. The National Park Service says to test any treatment on a small, inconspicuous area first and always to use the gentlest means possible. In Philadelphia, for a property on the historic register, the Historical Commission requires review for masonry cleaning, painting, pointing and for painting, coating, staining or sealing surfaces other than wood and metal trim. Scraping and painting wood trim counts as standard maintenance and needs no review.
Does combining washing and painting change the contract?
It can. Pennsylvania's Home Improvement Consumer Protection Act names painting among the work it covers, while washing on its own is not named. Where the total price of the work at a private residence is more than $500, the Attorney General says the contract must be in writing and signed by both sides, with a description of the work, approximate start and completion dates, the total price and notice of your right to cancel. A wash bundled with painting or staining is therefore a job to get in writing. What Pennsylvania requires explains registration and the rest of the law.
What does washing before a finish cost?
HomeGuide gives $0.50 to $1.50 a square foot to wash, stain and seal a deck, and $65 for each staircase. For a house wash alone, the national ranges are in the cost guide. Ask whether a painter's quote includes the wash and the containment that an older house needs.
A short checklist before painting
- Look for mold or mildew, and have it cleaned off and the surface dried.
- Find out when the house was built; if before 1978, use a lead-safe certified firm for paid work on painted surfaces.
- Ask how the washing will be contained and where the water will go.
- For vinyl, check the siding maker's position on painting.
- In Philadelphia, check whether the house is on the historic register before masonry is cleaned or coated.
- Get the combined job in a signed, written contract.
Pressure washing an older painted house covers the lead rule in full, and businesses that offer washing are on the pressure washing directory page.
Sources
- Mold Cleanup in Your Home, U.S. Environmental Protection Agency
- Springtime Means Deck Maintenance for Many Homeowners, USDA Forest Service, Forest Products Laboratory (news release via Newswise)
- Lead Renovation, Repair and Painting Program, U.S. Environmental Protection Agency
- How do RRP requirements apply to pressure washing? What containment and other preparation are required?, U.S. Environmental Protection Agency (January 2025 archived copy)
- Lead-Safe Renovations for DIYers, U.S. Environmental Protection Agency
- How to Clean Vinyl Siding, Polymeric Exterior Products Association (PEPA)
- Get approval for work to a historic property, City of Philadelphia
- Frequently Asked Questions: Home Improvement Contractor Registration, Pennsylvania Office of Attorney General
- Home Improvement Consumer Protection Act (Act 132 of 2008), Pennsylvania General Assembly
- Pressure Washing Prices, HomeGuide
- Preservation Matters: Maintenance - Graffiti Removal from Historic Features, National Park Service