What Can You Power Wash? A Homeowner's Guide to Decking, Wood Siding and Cedar Siding

Power washing can quickly remove years of dirt, pollen, algae, and grime—but the wrong pressure or technique can also cause permanent damage. Learn which exterior surfaces can be safely washed and when it is better to call a professional.

Before you start power washing, inspect the surface for damage, rot, loose boards, and peeling finishes. Review the manufacturer's cleaning instructions, start with the lowest effective pressure, use a wide spray pattern, and test a small hidden area first. Never point the spray toward people, pets, electrical equipment, windows, or roofing materials. When in doubt, contact an exterior professional.

What Is the Difference Between Power Washing and Pressure Washing?

While often used interchangeably, there is a key difference: power washing uses heated water, whereas pressure washing uses unheated water. The heat in power washing is particularly effective at breaking down grease, oil, and stubborn grime, making it ideal for concrete driveways and garage floors.

Pressure washing relies solely on the force of the water (measured in PSI) and cleaning solutions to remove dirt. For most residential siding and decking, unheated pressure washing—or even better, "soft washing" (which uses low pressure and specialized detergents)—is the preferred and safer method. For more on safe exterior maintenance, see our guide on insulated vinyl siding care.

Can You Power Wash Decking?

Yes, but with extreme caution. Wood is softer and more porous than concrete or brick. Using too much pressure or holding the nozzle too close to the surface can easily gouge the wood, splinter the boards, and strip away the protective sealant. The U.S. Department of Energy offers additional guidance on home exterior maintenance that may help you protect your investment.

Signs of Pressure-Washing Damage

• Raised or fuzzy wood fibers
• Deep lines or grooves
• Splintering
• Uneven coloring
• Stripped stain or sealer
• Water forced between boards

Can You Power Wash Wood and Cedar Siding?

Washing wood siding requires a delicate touch. High pressure can force water behind the siding boards, leading to trapped moisture, mold growth, and eventually wood rot. Cedar is a relatively soft wood, so high-pressure washing will almost certainly cause splintering and deep gouging. The best approach for cedar is soft washing with specialized cleaners and a very low-pressure rinse.

What Is the Right Power Washer PSI for Siding?

• Wood and Cedar Siding: Under 1,000 PSI, or rely entirely on soft washing.
• Vinyl Siding: Between 1,300 and 1,600 PSI to avoid cracking panels.
• Fiber Cement Siding: Under 1,500 PSI to avoid damaging the finish.

What Should You Never Power Wash?

Some areas of your home should never be subjected to high-pressure water:

• Asphalt roof shingles
• Electrical panels, outlets, and meters
• Exterior light fixtures
• Window screens and glass
• Air-conditioning equipment
• Loose or crumbling mortar
• People, pets, and plants

A pressure washer is more dangerous than it looks. Always wear protective gear, including safety goggles and sturdy shoes. Never use a pressure washer while standing on a ladder. If your siding is covered in stubborn algae or your deck is looking worse for wear, it is always best to consult a professional exterior contractor.