How to Power Wash A Deck in 5 Easy Steps

Here are some steps to ensure your deck is power washed correctly every time.

Step 1: Wash the Railings

Pressure wash the railings using a stripper. Start at the top and work your way down, keeping the tip 6 to 10 inches away from the wood. Spray balusters are positioned at the corners to clean two sides simultaneously.

Step 2: Power Wash the Deck

To ensure your deck is as clean as possible, you’ll need to invest in a good pressure washer. It’s essential to ensure that the pressure release power is high enough for this job.

If you need a light cleaning, it’s probably best to use a lower setting. However, you will want to use a higher setting for dirty decks that have been collecting mold, mildew, and grime for a long time.

Working on one section of your deck at a time is always a good idea so you don’t accidentally spread dirt from one area onto another.

Ensure that the correct type of tip is being used with your power washer- if it needs heavy.

Step 3: Remove any debris from the gaps between deck boards

With a putty knife, dig out trapped debris between deck boards. Then, spray the deck with oxalic acid and water to brighten it up.

Apply the stripper to the deck. Start with the top rails and work down the balusters. Use a 25- or 30-degree tip on the pressure washer’s wand and a PSI of 1,000 to 1,200. Spray the rails in a continuous, organized manner with the wand. You don’t want to scratch the wood by moving too quickly.

Start with the deck boards once you’ve completed the railings. First, wash down the length of the boards. Then wash the grime away from the wood.

Rather than increasing the pressure or heavily scrubbing the wood, go over stubborn mildew or other marks a few times. Later, we’ll deal with hard stains that won’t come off with the stripper.

The lignin removal in this stripping process washes away a tiny amount of the wood’s glue, which binds the wood fibers together. As a result, the fibers stand up as the lignin washes away, giving the wood a fuzzy texture. Don’t bother sanding the fuzzy fibers. They will eventually shear away, leaving only the smooth ones.

After you’ve finished power-washing the whole deck, rinse all of the wood with plain water to remove any remaining stripper. Next, remove any debris trapped between deck boards, such as leaves or twigs, if there is still any.

Step 4: Apply a Chemical Stripper/Brightener (Optional)

Stains are not the only reason to clean your deck. Deck surfaces can also get dark, dull, or moldy over time despite regular cleaning. If this is the case, you may want to consider applying a chemical stripper/brightener. The wood will need to be left to dry for several hours before being ready for staining.

Step 5: Examine the whole deck and repair any loose boards

Remove any nails or screws that may be sticking out. Replace any missing or loose fasteners with longer screws at least 1/2″ longer than the original. Identifying areas that require more attention when the deck is clean is simple. 

Remove any nail heads that are emerging from the deck boards. Look for missing or loose screws and replace them with corrosion-resistant screws that are a little longer than the original. Replace rusted or missing nails with corrosion-resistant “trim head” screws, which have a considerable finish nail appearance and are tiny.

Check for loose lag screws or bolts in your ledger board, rails, or posts. Also, look for indications that the flashing between your deck and house has fallen out of place.