How to Power Wash a Deck

Wood decks are a great addition to homes, transforming a section of the backyard into another room. Here, you will learn how to make your deck look new again by removing algae, dirt, mildew, and grime embedded in the wood using a power or pressure washer.


  1. Image titled Power Wash a Deck Step 1
    Ensure that all materials are present, and that the engine has sufficient gasoline and motor oil.
  2. Image titled Power Wash a Deck Step 2
    Attach water source to washer. Do not attach hot water source unless your pressure washer is made for this or you may cause internal part failure.
  3. Image titled Power Wash a Deck Step 3
    Turn faucet on at full blast.
  4. Image titled Power Wash a Deck Step 4
    Pull the choke a few clicks in the opposite direction of the arrow (check with your model).
  5. Image titled Power Wash a Deck Step 5
    Gently pull the red handle from stop to the turtle or rabbit.
  6. Image titled Power Wash a Deck Step 6
    Standing behind the washer, firmly grasp the manual pull crank and quickly pull the rope towards your hip. The engine should start with one to two motions. If the engine is not starting easily, adjust the choke and/or red handle as needed.
  7. Image titled Power Wash a Deck Step 7
    Once the engine begins to roar, pull the red handle all the way to the rabbit and pull the choke as far as it will go.
  8. Image titled Power Wash a Deck Step 8
    Clean vertical railings with a smooth up-down-down-up motion.


  • They can be fun to use for the first hour. Take frequent breaks, because operator fatigue can occur from dragging long water hoses around your property.
  • If this is your first time pressure washing, or you just haven't done it in a long time, practice first in an inconspicuous area.
  • If you are planning to also paint or coat the surface, allow 3 or more drying days for wood to release the water you have injected.
  • Caution: Depending on the pressure, you can dig a hole in wood.
  • Divide the project into sections. Work on one section, take a break or do another activity, and return to complete another section.
  • When filling up the engine, gently tap the machine to dislodge bubbles that may be trapped in the tank. A fuller engine means more performance time.
  • Work the boards lengthwise whilst keeping the spray perpendicular to the wood.
  • Pressure washers are generally very loud and annoying to others.
  • Nozzles usually have a rotating end that will adjust the shape of the water exiting the handle from "stream" to "fan." The "stream" concentrates the pressure of the water into a jet and is ideal for cleaning out spaces in between boards and crevices. The "fan" setting is a much wider triangular plane and has a slightly lower working pressure exiting the nozzle. This can be used over a larger work area or an area that cannot withstand very concentrated pressure. A setting of 90% "fan" and 10% "stream" provides enough bite to be able to readily clean floorboards quickly while covering a lot of ground with each movement of the handle.


  • Ensure that no one is standing behind you while you pull the manual crank. An elbow or clenched fist ramming into someone's groin or face will ruin anybody's day.
  • The high pressure of the water can easily cause serious harm to fingers and hands if they are directly in front of the stream.
  • If the water pressure has been building up during idle, the handle may kick back when the trigger is depressed. Brace yourself, pull the trigger, and give the washer a moment to restore normal pressure, then continue working.
  • Use ear protection as the noise from the engine is quite loud and the water hitting the wood will make a high-pitched screeching sound.
  • On the same token, do not intentionally startle a person working. He/she may spray you or swing the handle in self-defense. Walk within eyesight of the person (not too close) and wave an arm to get his/her attention.
  • Do not duct tape the trigger handle because you don't want to keep holding it down for the duration of the project. The trigger works like a dead man's switch- when your hand comes off, the water stops flowing.
  • Water exiting the nozzle comes out at very high speed and pressure. DO NOT point the end of the nozzle at any person or pet, even as a joke.
  • Pour the gasoline slowly. If any spills occur, wait for the gasoline to evaporate before starting the engine.
  • Do not hold the nozzle at one area for more than a few seconds, especially when water is coming out as a tight stream. The wood fibres will be splintered as well as leaving a tell-tale mark.
  • Do not let the engine idle for too long.
  • Keep gasoline and other flammables away from the heat of the engine.
  • If you are using synthetic motor oils, the oil will need to be checked more often.

Things You'll Need

  • Deck
  • Pressure washer
  • Hose attached to water supply with adequate pressure
  • Regular unleaded gasoline
  • Motor oil
  • Ear protection
  • Wellington boots (optional)

Article Info

Categories: Walls Fences and Decks