Power washers can be powerful enough to carve into brick or gentle enough to remove a few cobwebs. For cleaning a wooden deck, you'll be best served by using the lowest pressure setting that's still effective. For soft woods like cedar or pine, this is usually about 500 to 600 psi.
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.
Best for Patios and Decks
After our testing, we think the Greenworks 2,000-PSI Pressure Washer is a great choice for just about any light-to-medium cleaning task around your home. Thanks to the included 11-inch rotating surface cleaner, it's even more helpful when you have a large stretch of flat surface to clean.
You may have read or heard your neighbor say that you shouldn't pressure wash your deck, because you can damage the wood fibers, or even scar the wood. That is very true! In the wrong hands a pressure washer can cause considerable damage to the integrity of the wood. Use fan tips of at least 30 degrees.
Electric pressure washers are generally seen as light-duty power tools because they do not generate the same amount of power as a gas pressure washer. On average, the power output of an electric pressure washer will produce about 1.5 to 2.5 GPM at a water pressure that ranges from 1,500 to 3,000 PSI.
Because electric pressure washers have to be plugged in, they have less mobility on a job site than a gas model. They are also less suited to heavy-duty cleaning. Pro Tip: More power means more noise.
A power or pressure washer is often the quickest option for cleaning your deck as it requires less physical effort and can sometimes be completed in less than an hour. That said, power washing can damage softwoods and can cause splintering or other structural issues if not used properly.
A pressure washer is a straightforward machine that can clean very well with only water. However, it can ruin your deck if it's not used properly. This is a tool that is powerful enough to etch brick, but in the right hands, it can be gentle enough to wash siding.
After you've pressure washed your deck, you'll need to wait for it to completely dry. Sometimes, this can take as long as 48-hours. Once it's dry, you'll want to sand your deck lightly. This is necessary to remove any splinters or fuzzy patches that pressure washing can cause.
The larger your deck, the more frequently you should power wash it. For decks up to 500 square feet in size, it's usually recommended to be power washed once every year. For decks larger than 500 square feet, it's recommended to be power washed twice a year.
The best deck cleaner is the Star Brite Non-Skid Deck Cleaner. It removes tough stains without heavy scrubbing and leaves behind a nonskid surface. For a budget-friendly choice, consider the Simple Green Oxy Solve Deck and Fence Pressure Washer Cleaner.
First of all, you need the right pressure washer. We recommend around 2400 PSI for the average deck. This makes the job easy without damaging most woods. Start by using the standard spray tip to get rid of any loose dirt, leaves, and other easy debris.
Applying Pressure
Although highly effective for cleaning concrete, applying this much pressure to your deck can cause irreversible damage. To clean a deck effectively, about 1,500 pounds of pressure will do the job nicely, without causing permanent damage.
Spray the deck lightly with a mixture of oxalic acid and water to brighten the wood. With a 25- or 30-degree tip in the wand of the pressure washer and a psi of 1,000 to 1,200, apply the stripper to the deck, starting with the top rails and working down the balusters (Photo 1).
This looks like very small raised wood grain fibers or hair on the decking boards. When you are prepping a deck you essentially remove a layer of oxidized or damaged wood cells. The more you need to remove, the greater the chance of making the wood look “fuzzy” or “soft”.
Once you pressure wash your deck, it'll look like new timber again but it won't stay that way for long. If you like the grey look, then you could pressure wash to remove the grime then let it grey off again. It is best to seal it if you want it to last longer but you won't get that grey look.
Use the Right Pressure and Tip Settings
A PSI of between 500 and 600 will be enough to blast away the tough dirt without removing the deck stain. However, if the deck is made of hardwoods like Garapa and Ipe, you can use a higher pressure of about 1200 PSI.
We recommend power washing your deck during the spring when you have mild weather and can clear away the build-up from the nasty winter weather. If you missed the window this year, you can power wash your deck during the fall to get ahead of cold-weather grime.
Generally speaking, a good principle is to have the deck pressure-washed when the temperatures remain above 52 degrees both at night and during the day without rain or other condensation for several days. This allows the deck to dry as quickly as possible.
Do you have to sand a fuzzy deck or can you leave it? If you are not coating your deck and you don't mind that fuzzy appearance, then you can leave it. But if you're going to give your deck a coat of stain or oil then you'll need to remove the fuzzies.
For smaller jobs, an electric pressure washer will do the trick. These typically have about 1,000 psi to 1,500 psi, with a gpm no higher than 1.5. Quieter, lighter and cheaper than gas models and virtually maintenance free, they're good for washing stains off outdoor furniture and cleaning vehicles and vehicle tires.
The number one cause of low or no pressure when using a pressure washer is a blocked or worn nozzle. Blocked nozzles will prevent water from escaping, while a worn nozzle will allow too much water to pass through, causing the pressure to drop.
Pressure washers come equipped with either an all-in-one variable spray wand, which lets you adjust water pressure with a twist or a set of interchangeable nozzles.