How to Pressure Wash a Deck?

Pressure washing a deck can be done by following 7 easy steps:

Step 1: Prepare the area for cleaning.
Step 2: Select the right pressure washer PSI levels.
Step 3: Select the right pressure washer nozzle tip.
Step 4: Check the pressure washer’s spray jet.
Step 5: Clean the deck with the pressure washer using clean water.
Step 6: Apply chemicals if needed using the pressure washer.
Step 7: Rinse the deck and let it dry for 24 to 48 hours before applying any treatment.

These steps on how to clean a deck using a pressure washer are discussed in detail in this article.

Contents show

1. Prepare the Area for Cleaning

Pressure washing a deck requires the operator to prepare the surface that needs to be cleaned in order to avoid injuries and damaging the material the deck is made of.

These steps need to be followed to prepare a deck for pressure washing:

Remove all the plants from the deck.
Remove any objects that might lead to tripping or could get damaged if they come in contact with high pressured water.
Swipe the deck using a broom to remove debris, needles, rocks, or other small objects that could be propelled by the water jet, as they might cause severe injuries.
If there are any plants in close proximity to the deck, cover them with a tarp to avoid damage.

Pro tip: Keep children and pets away from the area that needs to be cleaned to diminish the risk of injury.

2. Select the Right PSI

Pressure washing decks or surfaces made of wood requires low PSI levels to avoid damage. The safe range for this type of surface is between 500 PSI and 1500 PSI. Try not to go above that, as the outer layer of the wood might get deteriorated. The ideal pressure is 500 – 600 PSi for softwood types and between 1200 and 1500 PSI for hardwood types.

Before using the power washer, make sure that the unit withstands such low PSIs, as some machines have minimum PSI levels above the recommended rates. These units are usually gas pressure washers that are more powerful. The pressure washer should have onboard pressure settings that allow the user to adjust the pressure. If the unit is not equipped with adjustable pressure settings, it will have a valve that allows the operator to diminish or enhance the pressure.

3. Select the Right Nozzle

For pressure washing a wooden deck, the white power washer nozzle tip is ideal, as it sprays at a 40-degree angle. This angle is suited for fragile or painted surfaces because it is the most gentle of all. The white nozzle is also called the wash nozzle, which is perfect for cleaning large areas faster than using other standard power washer tips.

4. Check the Spray Jet

Before pressure washing the deck, make sure that all the settings are correct. Test the spray jet of the power washer on a small part, at the corner, or somewhere where eventual damage is not visible. To avoid damaging the deck, the pressure washer should be set to its minimum PSI levels and the pressure should be raised until the cleaning results meet the cleaning needs.

5. Clean the Deck with Water

There is a technique that needs to be followed in order to get the best results using a pressure washer. The best way to clean a deck is by following these instructions:

Check the direction of the wind and position the pressure washer spray jet correctly in order to avoid getting wet.
Keep the pressure washer nozzle at an 18-inch distance from the deck at all times. If this is not possible, never bring it closer than 12 inches, as the pressure will increase and will ruin the wood.
Start from the back and finish the cleaning job at the entrance of the deck.
Pressure wash each deck board separately and go on its length.
Use sweeping motions and don’t stop pressing the trigger until each board is finished, to avoid damage.
Make sure not to leave any parts uncleaned, as it will lead to differences in color.
Pressure clean the deck twice for best results. Repeat the process by overlapping the first cleaning set.

6. Apply Chemicals

Applying chemicals to a deck is optional and should be done if the deck is really dirty and plain water was not enough to clean it. Using a pressure washer with chemicals requires that the operator changes the nozzle to a black soap nozzle. Always make sure to use chemicals that are specially formulated for pressure washers and also for wood, in order to avoid damaging the unit and the deck. Follow these instructions to apply pressure washer soaps:

Spray the cleaner evenly on the surface and try to avoid leaving stripes on a few boards at a time.
Use a rotating brush if necessary.
Leave the cleaner in for 5 to 10 minutes, or as instructed by the producer.
Avoid applying chemicals to an area that is under direct sunlight because the heat might influence the activation of the detergent. Avoid letting the chemicals dry in any conditions as stripes will remain on the cleaned surface.

7. Rinse the Deck

Remove any remaining chemical residue in the pressure washer.
Reconnect the power washer to a water supply and rinse the deck following the instructions from the first section of the article.
Start from the end and come slowly to the exit of the deck.
Leave the deck to dry out for 24 to 48 hours before applying sealants or other types of wood treatment.

Pro Safety Tips:

Close all doors and windows situated in close proximity to the cleaned surface.
Wear safety goggles and avoid clothing that might get entangled in the pressure washer accessories.
Never pressure wash a deck barefoot or while wearing sandals.
Once figuring out what PSI level works best, don’t change it in the middle of the task, as it might lead to differences in cleaning performance and the final result might not be the same on all the parts of the deck.
If the plants alongside the deck are not protected, position the pressure washer so that heat from the engine will not damage the plants.

Don’t use a hot water pressure washer to clean a deck, as it might damage the wood.