Don’t Clean Deck with Pressure Washer

by Paul Bianchina, Inman News
Power washerQ: We just cleaned our cedar deck with a product that smells like bleach. We also used a pressure washer (before reading in your column that we probably shouldn’t) and now the deck is gray and fuzzy. We also put on a coating of Thompson’s Water Seal, but it didn’t help. Is there anything we can do now to make the deck look better? –Gary B.

A: Your first step is to remove the gray appearance and the fine fuzzy layer — which is actually wood fiber that’s been torn up by the impact of the high-pressure water. Depending on the severity of the “fuzz,” you can do this with a stiff nylon brush, or you may need to actually sand the deck.
If you have to sand it, first make sure the deck is completely dry. Then I would suggest starting with 40- or 50-grit paper and working up to 80- to 100-grit. Don’t go any finer then that, as this will actually smooth out the wood too much and lessen the ability for the finish to penetrate. Depending on the size of your deck, you may want to use an electric random orbit sander, or rent a larger flooring sanding and then use the random orbit to finish up in those areas you can’t get to effectively with the larger machine.

Remove the sawdust with a soft push broom, and then follow with a leaf blower or similar blower to get the wood as clean as possible. Finally, I would recommend a penetrating stain with UV inhibitor that is formulated specifically for decks. Talk to the folks at an experienced paint store for their recommendations (I would typically avoid the home centers for advice on something like this), and be sure to tell them about the Thompson’s, as that may affect the penetration of any new product you apply.
Initially, you will probably need two applications of stain to get the color and protection you want. After this initial treatment, in the future I would maintain the deck with a fresh application of stain every two years.

Q: I very much enjoyed your deck-cleaning article. Do you have any brand-name product recommendations for deck cleaning? –Lee G.

A: Over the years, I’ve had very good success with deck maintenance products from the Wolman company, which are sold at many home centers and paint stores. You can check out their entire product line, along with specific details on what product is used for what application, by visiting their Web site at

Q: I have a complicated deck-cleaning question. I have an untreated cedar deck, which is on a houseboat directly over the river. How can I safely clean it without getting toxic material into the water? Thanks for the advice! –Jean F.

A: As to what specific product to use on the deck that’s over the river, I contacted Wolman’s technical representatives and posed the question to them. They recommended one of their products called DeckBrite in powdered form, which is safe for use in and around water.

Q: I have a large, ground-level cedar deck and prefer not to use any harsh chemicals to clean it because I have flowers and other vegetation around it. Can I use vinegar and water, or perhaps a biodegradable soap? –Barbara D.

A: For periodic light cleaning of your deck, I would suggest trying a powdered, biodegradable laundry soap mixed with water and applied with a long-handled, nylon brush. Sweep the deck first and try not to overly saturate the wood while cleaning. Rinse with clean water, using a garden hose with a wide spray nozzle.

After the deck is clean and dry, I would strongly recommend treating the cedar with a penetrating stain with UV inhibitor. This will maintain the deck’s color, and will help prevent breakdown of the wood fibers (fibers that break down will trap more dirt and over time will make the wood harder and harder to clean). Incidentally, there are a number of colors available in penetrating stains, ranging from natural for new decks to gray, which is ideal if your cedar has grayed over time and you like that tone.
Remodeling and repair questions? E-mail Paul at [email protected]. What’s your opinion? Send your Letter to the Editor to [email protected]. Copyright 2008 Inman News

Click here to read our feature on deck finishes, Choosing a Deck Stain: Aesthetics vs. Durability.

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