7 Steps to Power Wash a Deck Without Damaging It, According to the Pros

If your deck has weathered over the years — its once-vibrant desert tan or chestnut brown color fading into a silvery gray tone — re-staining can extend its lifespan without requiring a full replacement that could cost you upward of $14,000.

But before you can add that fresh layer of stain, you’ll need to get the surface sparkling clean for a smooth application. When the layers of dirt and grime are too thick and embedded to remove with a simple broom sweep and spray-down, the pressure washer can be your best friend, so long as you know how to use it properly.

For expert guidance on how to power wash a deck, we turned to John Amabile, owner of A&J Power Washing of Staten Island, New York, which also serves Brooklyn and northern New Jersey. Amiable has been in business for 30 years and is a member of the Home Improvement Contractors of Staten Island.

In addition, top-selling real estate agent Edward Kaminsky of Manhattan Beach, California, offers his own real estate pro tips, as well as insights into how taking care to power wash and refresh your deck can vastly improve your home’s marketability at resale.

Ready to roll up your sleeves and get your deck looking like new? Follow these steps!

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1. Select the right power washer

To clean a deck, some homeowners choose a washer with a pressure range of 1,300 to 2,400 psi, the same as washing a car. HGTV recommends working with the lowest pressure that cleans your deck materials gently: about 500 to 600 psi for soft woods like cedar or pine, and up to 1200 to 1500 psi for pressure-treated wood.

Amabile likes a 2000 psi machine, which Home Depot rents for $38 per day. You’ll need a wide nozzle of 15 or 18 degrees. These are typically either green or yellow.

Pro tip: Although people tend to use the terms “power washing” and “pressure washing” interchangeably, they’re different processes that involve different equipment, according to Fixr.com. Both create high-pressure water from a garden hose, but a power washer heats the water; a pressure washer does not.

While the cost of power washing and pressure washing is roughly the same, each has its advantages and disadvantages. Power washing is quick, but the hot water might break up fragile or deteriorated wood. Pressure washing is milder on fragile surfaces, but it might not remove heavy soil or mold and mildew as well as power washing. If you’re unsure about what your deck can withstand, consult with a professional first.

2. Use a deck brush to pre-treat the surface

Before you put that power washer to use, see what you can achieve with some suds and water. Amabile recommends pre-treating your deck by applying a mixture of water and mild dish detergent or non-toxic oxygen bleach with a deck brush, he says. If you have a composite deck with no worn-in grime, no power washing is necessary; just rinse away these suds with a garden hose.

3. Practice using the equipment

Check the instructions included with your power washing equipment, and practice using it on an inconspicuous area, such as a stair tread, at low pressure. If you’ve never used this type of equipment before, you can easily score concrete if you don’t know what you’re doing, Amabile says. “You could even damage a house, especially if it’s stucco. You’ll put a hole in it,” he says.

You’ll also want to be careful to keep the water away from the house to avoid mold issues. “If you’re spraying it toward the doors, it could create a mold situation. Houses are not waterproof,” Kaminsky adds.

4. Prep the area

Before you begin power washing, cover any electrical components, light fixtures, and nearby plants, Lowe’s recommends. (The water won’t hurt the plants, but the pressure might.)

In addition:

• Close nearby doors and windows
• Remove any obstacles such as planters or furniture that can tangle the cord
• Pay attention to the direction of the wind, which will carry the spray
• Wear safety goggles
• Make sure pets and children are indoors

5. Work systematically

OK, you’ve got the right power washer, pre-treated the deck with a soap and water solution, protected the surrounding area, and you’re ready to get down to business. As you pressure wash, keep the nozzle at least 12 to 18 inches away from the surface, and spray the water in even strokes in the same direction as the wood grain, Amabile says.

Go back over the area to avoid patchy spots, but don’t move the sprayer back and forth or in a zigzag pattern. “You’ll score the wood,” warns Amabile. “Be careful that the water doesn’t pool in the deck corners,” Kaminsky adds.

“You’ll want to make sure the water has a way off the deck so it dries well.”

If it doesn’t drain completely, experts recommend removing any standing water with a mop, towels, or a rubber or plastic squeegee. Some homeowners also turn a gas-powered leaf blower on any puddles for five to ten minutes to thin out the water and letting the rest evaporate.

6. Let dry for a few days before any staining

Let the deck dry for two to three days before applying any stain, if possible. “Wood has pores, like concrete or our hands,” Amabile says. If you don’t let the deck dry adequately before staining it, the water that the deck absorbed will push up the stain in about a week.

Once you’re ready to stain, check out our Go-To Guide on How to Stain a Deck for advice on what to do next.

Not comfortable power washing? Consider these alternatives

If you’re not confident about using a power washer, you have other options:

Call in a pro

You can hire a power washing pro for about $50 to $150 per hour, although some charge by square foot. Expect to pay about $90 to $120 for 300 square feet up to roughly $450 to $600 for 1,500 square feet.

The cost to hire a professional to power wash a deck also varies by decking material. The average cost of power washing a 500-square-foot aluminum deck ranges from $150 to $180 because aluminum stands up well under a heavy stream of water, requiring less time. By comparison, power washing a natural wood deck of the same size costs about $180 to $200. Cleaning a composite deck of the same size costs about $200 to $220.

Sand it instead

Depending on the condition of your deck, you might want to sand it instead of power washing it, Amabile adds. Sanding will remove any old finish while flattening and smoothing weathered boards, a clean canvas for new finish.

Homeowners can rent an orbital sander to accomplish this, but again, if you’ve never used one or if your deck is larger than 100 square feet, he recommends hiring a professional who won’t damage the wood by over-sanding it.

Stick with the scrub brush

If your deck is in overall good shape, you may be able to clean your deck effectively using a mixture of mild soap and water, or water and non-chlorine oxygen bleach. This just takes more time and won’t be quite as efficient as using a power washer in tandem. If you go this route, we recommend scrubbing your deck with a brush such as the Quickie Professional Pool and Deck Scrub Brush ($7.99 at Home Depot), then rinsing it with a garden hose.

Know what your deck needs

For many homeowners, decks and roofs fall into the same category — something to fix or maintain only when broken, Kaminsky says. Yet according to Remodeling Magazine’s 2020 Cost vs. Value report, homeowners recoup about 67% on a composite deck addition and about 72% on a wooden deck addition, all the more reason to clean and maintain these home amenities regularly.

Amabile recommends the following regimen for different deck materials:

• Natural wood: Cedar, redwood, and other decks made of natural wood should be cleaned annually, then refinished.
• Pressure-treated wood: Clean every two to three years, applying new finish afterward.
• Composite material: Clean every two to three years, no refinishing necessary.

Kaminsky has seen homes with deck tiles, which can be made of hardwood, teak, mahogany, cedar, ipe, or stone such as porcelain. He recommends checking the tiles every year or two, depending on their materials, for areas that are lifting, peeling, or cracking. Then ask a licensed contractor to clean and reseal it as needed. “People tend to believe that tile is waterproof, and it is not. Water can get through the grout. When that gets damaged, it needs to be repaired,” he says.

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The payoff of power washing your deck

There’s no denying the appeal of a fresh, clean deck, whether you’re looking to personally enjoy the space for years to come or are getting ready to put your home on the market. With a pristine deck, “you’re creating an image that you’re taking care of your home,” says Kaminsky. “For the new homeowner that comes in, it’s something less for them to do.”

So there you have it. A well-cared-for deck gives your home an advantage, enticing buyers with thoughts of summer barbecues, lounging in the breeze, and dining under the stars — making your power washing efforts well worth the tired arms and a day spent sweating in the sun!

Header Image Source: (Margarida Afonso / Unsplash)