How to Pressure Wash a Deck

homeowner completing the step by step process of how to pressure wash a deck

As you gear up for some back yard enjoyment with a freshly cleaned home this spring, one daunting task you might be dreading is how to get your deck to look shiny and brand new. The simplest and fastest way to get that deck spruced up is with a quick pressure washing before staining or sealing it for the year. If you’ve never run a pressure washer before, this post will give you a step-by-step guide to how to pressure wash a deck safely and efficiently.

Step 1: Outfit Yourself for Power Washing Safely

Before plunging into a power washing frenzy, you’ll want to understand the importance of keeping your home, your family, your plants, and even yourself safe from a pressure washer.

As Consumer Reports notes, pressure washers pack up to 30 to 80 times the pressure you’ll get through your garden hose. With that kind of pressure, you can break windows, damage siding, and gouge your deck. While you can pressure wash siding to clean it, it generally requires less pressure and should be a separate project. You can also do some serious injury to yourself, which is why you should understand how to power wash a deck safely.

A pressure washer has the capability of causing lacerations that penetrate deep into muscle tissue, raising the risk of infection. A washer also can blast through lightweight footwear such as deck shoes or even light rubber boots, so make sure you wear long pants, sturdy work shoes or boots, and goggles. Also, avoid loose clothing or jewelry that could get caught in the spray and suck part of your body into it.

Step 2: Prepare Your Deck and Surroundings for Pressure Washing

Getting your deck ready for a power washing should be quick and easy, but it’s also an important step.

Start by moving all of your patio furniture, toys, and decorative items so you can clean them separately. Be sure to move anything fragile that could be damaged by the power washer far away from the area. Also, sweep the deck clear of all winter debris, such as leaves, branches, and dirt.

Examine the deck closely to see what level of cleaning you’ll need to undertake. As you better understand how to pressure wash a deck, you’ll also know what can be accomplished by a simple washing and what requires a little extra effort. If you have deep-stained areas from grease, tree sap, and other deep stains, you might need to consider applying a cleaner before pressure washing.

If you live in a rainy area and have spots with mold and mildew, you’ll definitely want to treat those areas with a fungicidal or antimicrobial cleaner. A deck that just needs a little refreshing can be cleaned nicely with just plain water in the pressure washer. We’ll touch on some of the tougher cleaning solutions in a bit.

Pro Tip

Any plants close to your deck should be covered with plastic while you are pressure washing. This will stop direct spray damage and reduce exposure to chemical residue. Plants close enough to catch some drift from your spraying, especially if you use a cleaner first, should be rinsed off as soon as possible. This extra step can protect your landscaping.

Step 3: Using a Cleaner on Your Deck

As we mentioned before, the condition of your deck will determine the need for using a cleaner before power washing. Here are three common scenarios that require chemical cleaners:

Mildew and Mold

Treat those areas with a cleaner that includes a mildewcide a few days before you start pressure washing. Mold and mildew, if left untreated, will damage the cellular structure of the wood and lead to rot and decay.

Mop or spray the cleaner on the affected areas, but do not rinse it away. The cleaner needs time to kill the buildup. Also, the cleaner will soak into the wood and prevent mildew and mold from returning.

Grease or Sticky Stains

Use a cleaner rated for your type of wood. Then mop or spray the cleaner on and scrub with a deck brush. Make sure the bristles on the brush are the proper type for your wood. Some woods are softer than others, so you will want one that will do the job but not damage the deck.

General Cleaning

If you think you need more than a clean water cleaning, you can opt to wash your entire deck with a concentrated cleaner that is poured into a mixing tank on the pressure washer. Use the special soap nozzle on the pressure washer and the lowest possible pressure setting.

Step 4: Pressure Wash Your Deck’s Surface

homeowner pressure washing the edge of their deck

After all of this buildup, it’s finally time to crank up the machine and get to some power washing. You’ll be pleased to have the job tackled in about 30 minutes for a standard-sized deck. Here are the individual steps for how to pressure wash a deck once all of the prep work and chemical treatments are finished:

1. Choose the best nozzle setting.

Pick the widest-angle nozzle that comes with your sprayer, somewhere between 45 and 60 degrees. You can use a rotating nozzle, but they are trickier to handle.

2. Choose the right pressure setting.

If your deck is a soft wood such as cedar or pine, you’ll want to start with a low pressure around 500 psi. These woods can’t handle pressures above 800 psi. For harder woods, you can go up to 1,200 psi. Start with a low pressure and increase as needed.

3. Know the proper technique for how to pressure a deck and other surfaces.

The best method for how to pressure wash a deck without causing damage is to use a sweeping motion with your arm. Start with the sprayer wand pointed into an empty space about two feet above the deck. Then lower it to about one foot above the surface to start cleaning. Spray along the grain of the wood. This will prevent a rippling effect or sharp lines as you start and stop. Apply a slow, sweeping motion. Also, overlap the back-and-forth rows to feather the pressure and avoid creating sharp edges or lines.

4. Pressure wash the different parts of your deck in the right order:

Corners and Along the House:

The trickiest part of how to pressure wash a deck is cleaning the corners and where the deck meets the house. Keeping the pressure low, start a few feet away and work your way slowly into the corner or seam. Be cautious about spraying into the siding. It might be softer than the wood, and you don’t want to damage your siding. Once you’ve created enough room for yourself to stand, you’ll want to reverse course and start cleaning away from the house.

The Remainder of the Deck Surface:

As you work away from the house, pivot with your arm in small sweeps to maintain at least a foot of distance between the sprayer wand and the deck. When you encounter a tougher stain, be patient. Let the pressure washer do the work. Though you can move in a little closer, never get closer than six inches from the wood. Make sure the feather past the ends of the boards but try not to damage nearby plants. Some people prefer more of a train track method, where they power wash down the length of each board. But this method takes longer and runs a higher risk of leaving harsh start and stop points.

Railings and Handrails:

Keep the wand one foot away from the wood surface, and maintain the movement of the wand along the grain of the wood. Handrails can be tricky since you’ll be holding the wand high. But you don’t want to damage them and create a risk of splinters when people grab them.

Pro Tip: Practice how to pressure wash a deck on a test area first.

Try out your skills on an inconspicuous area or someplace that would be easy to replace if you mess up, such as a deck step. It would be easier to replace one tread than a full deck board or corner boards.

Step 5: Finishing Off Your Deck

You’re probably going to find some rough spots along your deck where the pressure washing raised the grain of the wood. Even experienced homeowners who know how to pressure wash a deck can find these raised sections. Sand these areas down with a medium-grit (60 or 80 grit) sandpaper using a random orbital sander. Use a finer grit, such as 100, for handrails as you’ll want to eliminate splinter risks. Too fine of a grit on the deck flooring will clog the pores of the grain. Then the wood will be unable to absorb the sealant fully. Make sure the wood is completely dry from the washing before sanding.

At this point, you should be ready to apply your favorite sealant or finish to make your deck the focal point for your outdoor enjoyment. Then you can enjoy your freshly clean deck as you host parties and relax all summer long. Once you know how to pressure wash a deck, backyard maintenance is easy to manage year after year.

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