Pressure washing questions and answers for Pennsylvania homeowners
Updated · KeystoneProGuide editorial team
How much does it cost to pressure wash a house?
Angi and HomeAdvisor both report that most homeowners pay $213 to $449, with an average of $312, though both are national figures. Height, square footage and the surface all change the price. The cost guide sets the published ranges side by side, including roofs, decks and driveways.
Should every surface be washed at high pressure?
No. The bodies that speak for each material ask for less pressure, not more. The shingle makers, the vinyl siding makers and the National Park Service all describe gentle or low-pressure cleaning for their materials, and the questions below give their words.
Can an asphalt shingle roof be pressure washed?
Not according to the shingle makers' trade association. ARMA says high-pressure washing systems are likely to damage asphalt roofing and should not be used for algae or any other purpose. It describes a household bleach and water solution, gently applied and gently rinsed, and says the result is only temporary.
Can vinyl siding be pressure washed?
With caution, says PEPA, the siding industry's association. It says to hold the washer straight at eye level, since aiming upward can force water behind the panels, and notes that some siding makers do not recommend power washing at all. For routine cleaning it says a rinse with a garden hose is often enough.
Is it safe to pressure wash old brick or stone?
Only gently. The National Park Service says to use a low-pressure spray of 100-400 psi with the wand at least 12 inches away, and warns that some historic materials can easily be damaged even at low pressure. It says most power-washing equipment in hardware stores runs at 1600-3200 psi.
Can I pressure wash my deck before staining it?
A deck does need cleaning before it is refinished, but a Forest Products Laboratory chemist warned that aggressive scrubbing or using a power sprayer can do damage to the wood surface. He suggested letting a cleaner do the work, rinsing with a garden hose and letting the deck dry for at least a day before finishing.
What if my house was built before 1978?
Then painted surfaces may contain lead. The EPA says about three-quarters of U.S. homes built before 1978 still contain some lead-based paint, and it requires anyone paid to disturb painted surfaces in those homes to be certified in lead-safe work. Ask any company you hire whether it is.
Do pressure washing companies need a license in Pennsylvania?
No state license exists for washing; the Department of Labor and Industry says the state has no licensure for most contractors. Home improvement registration with the Attorney General may apply, and the state's contractor search lists "Pressure Washing" as a type of work. What Pennsylvania requires covers the details.
Is a pressure washer dangerous to use?
It can be. The Centers for Disease Control and Prevention (CDC) says the spray can cause serious wounds that might first appear minor, can throw objects at people nearby, and can cause electric shock if safety instructions are not followed. It urges anyone with a spray wound to get medical attention as soon as possible.
Can a gas pressure washer be run in the garage?
No. The CDC says never to use a gasoline-powered washer in an enclosed space or less than 20 feet from any window, door or vent. The Consumer Product Safety Commission (CPSC) names power washers among engines that produce carbon monoxide and says that even with doors and windows open, enclosed spaces can trap CO.
Is bleach safe to use on a house?
It needs care. The EPA says never to mix chlorine bleach with cleaners that contain ammonia, because toxic fumes could be produced. ARMA tells people using its bleach solution on roofs to protect the surrounding landscape, and PEPA lists undiluted chlorine bleach among products that can damage vinyl siding.
Where should the wash water go?
Not into a storm drain. The Philadelphia Water Department says only rain should go in storm drains, because they lead to streams and rivers, and it lists mop water among things to keep out.
Will washing get rid of mold or algae for good?
Not on its own. ARMA says roof algae may come back after cleaning, and the EPA says no mold will grow without water or moisture, so the cause matters as much as the cleaning. The EPA also says mold can leave stains it may not be possible to remove.
Can I paint right after washing?
Not over mold. The EPA says to clean moldy surfaces and let them dry before painting, because paint applied over moldy surfaces is likely to peel. On a deck, the Forest Products Laboratory chemist suggested waiting at least a day, and said two to three were probably better.
How do I find a good company?
Check the registration, ask about lead-safe certification if your home is old, and ask how each surface will be cleaned. How to choose a pressure washing company lists the checks in order, and local businesses are on the pressure washing directory page.
Sources
- How Much Does It Cost to Pressure Wash a House? [2026 Data], Angi
- How Much Does Pressure Washing Cost? [2025 Data], HomeAdvisor
- Algae Discoloration of Roofs, Asphalt Roofing Manufacturers Association (ARMA)
- How to Clean Vinyl Siding, Polymeric Exterior Products Association (PEPA)
- Preservation Matters: Maintenance - Graffiti Removal from Historic Features, National Park Service
- 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
- Contractor Licensing, Pennsylvania Department of Labor and Industry
- Home Improvement Contractor Search, Pennsylvania Office of Attorney General
- Pressure Washer Safety, Centers for Disease Control and Prevention
- Carbon Monoxide Fact Sheet, U.S. Consumer Product Safety Commission
- A Brief Guide to Mold, Moisture and Your Home, U.S. Environmental Protection Agency
- Mold Cleanup in Your Home, U.S. Environmental Protection Agency
- Taking Care of Storm Drains, Philadelphia Water Department