Should a Cedar Deck Be Power Washed?

Benefits

• Using a power washer to clean a cedar deck yields beneficial results beyond simple cleaning. While the pressurized water will blast away dirt, grime and cobwebs, it also will remove the outer layer of the wood without damaging the core structure of the wood. This saves you time on stripping any finish, such as paint or stain, that might still be lingering on the surface. Any superficial damage, such as water stains, will also be removed.

Power Washer Recommendations

• When selecting a power washer for the job, stick with a machine that operates within the range of 1,500 and 2,000 psi. This amount of pressure is sufficient for cleaning and stripping your cedar deck. Anything stronger than this is too aggressive for wood surfaces and will damage your deck. Power washers come with different nozzles that concentrate the stream of water differently; 25-degree and 15-degree nozzles are best for power washing a deck.

Washing the Deck

• Before you wash the deck, remove any furniture or other objects that may get in your way as you wash. If you're not familiar with power washers, start with the 25-degree nozzle until you get the hang of using it. Switch to the 15-degree nozzle once you are comfortable with the power washer -- the 15-degree nozzle is a bit more aggressive. Wash all of the deck's surfaces, including the underside if you can reach it, with the power washer.

Stripping, Staining and Sealing

• Once you've finished cleaning the deck, there may be darkened spots where water seeped through the old finish. Before you stain the deck, wash it with oxalic acid, a wood-bleaching agent, to get the cedar back to its original color. Mix and apply the acid according to the manufacturer's instructions. Once the deck is stripped, you can apply wood stain and sealer, such as polyurethane. Both products should be formulated for use on exterior surfaces -- this information will be on the label.