Ask the Cleaning Experts – Composite Deck Needs Help

The Cleaning Experts at  A Clean Streak answer your toughest cleaning questions.

Cleaning a dirty deckKris L. from Anacortes asks: Help! This past March we moved into a beautiful house that has a wrap-around outside deck made of some sort of composite material (not wood). Now that spring has rolled around, we want to take full advantage of this outdoor space, but when we moved the old oak whiskey half-barrels the previous owners used as planters, we found the decking to be stained. We also found some grease stains on the boards in one corner of the deck where they must have kept their barbecue grill. My husband Ray wants to rent a pressure washer (which he’s never used before) and blast all these stains away, but I’m worried we’ll damage the decking. Do you have any suggestions to clean up this mess?

A Clean Streak, The Window Cleaning Experts answer:  Hi Kris. Composite decking does require special treatment, because while those boards may look like they’re impenetrable, they’re actually quite porous. We don’t recommend your husband Ray rent a pressure washer unless he’s a very experienced user.  Yes, composite boards can withstand some direct water pressure, but if he inadvertently holds the wand too close to the surfaces, uses any attachment but a fan attachment, and/or sets the pressure too high, the pressure washer can actually etch the boards resulting in a host of other issues further down the road, including mold, sun damage, and chipping. But don’t despair; with some basic cleaning supplies and a lot of elbow grease, you’ll be enjoying a clean deck for the summer!

Since you described two different kinds of stains, you’ll need two different cleaning solutions. Cleaning a Dirty DeckFor those dirt and mold stains caused by the planter, you’ll need some white vinegar and baking soda. First, spray the stained area with a garden hose (if you have a nozzle, you can use the highest setting as it doesn’t create enough pressure to harm the decking). Then, mix a solution of two parts vinegar to one part water in a bucket and pour it over the stain, liberally sprinkling the baking soda over the area. After about 20 minutes, scrub the area with a medium bristle brush and rinse with fresh water. If you still see staining after the area has dried, you’ll need to repeat the process. If those barrels hadn’t been moved in several seasons, the mold and dirt may have penetrated well into the boards, and it will take several applications of your vinegar/baking soda solution to eradicate all that mold.

Cleaning up old food and grease stains requires a different approach. Ideally, the sooner you remove a grease stain, the easier it will be, but it sounds like your situation is less than ideal. First, try wiping up as much of the grease as will come off with paper towels. Then, spray the area with your garden hose. Mix a tablespoon or so of dish detergent (we suggest you use an eco-friendly product) into a gallon of hot water and pour the solution over the grease. Scrub the area with a medium-bristle brush, and then with a wet sponge. If the grease isn’t coming out of the boards, pour some dish detergent directly onto the stain and let it sit for 20 minutes before scrubbing with the brush again and wiping with the sponge. Finally, blot the area with paper towels to remove the soap and any remaining grease that has come out of the boards. Spray the area with your garden hose and let it dry. You may have to repeat this process a few times to completely rid the boards of grease.

Thanks for contacting us Kris. Removing mold and grease from your composite decking will certainly extend the lifetime of your deck (not to mention improving the appearance)! We hope our tips will help you conquer those stains without the risks of pressure-washer damage, but if this project sounds overwhelming, we invite you to give us a call.  At A Clean Streak, we have the equipment and know how to clean your deck completely and professionally. For a free project estimate, call us 360-395-5748 today.

WA License # CLEANCS851PA

If you have a question for us, EMAIL the pros at A Clean Streak or call us at 360-395-5748 today.