How to Power Wash Siding

By Gene and Katie Hamilton

Tools Required
  • Power washer
  • Garden sprayer
Materials Required
  • Drop cloths
  • Waterproof tape
  • Detergent for power washer
  • Mildew cleaner
  • Household bleach
  • Garden hose
  • Garbage bags

Before You Begin

The control that varies the pressure of a power washer is called its psi (pounds per square inch). For most cleaning projects, especially on wood, 800 to 1000 psi is adequate. On less vulnerable surfaces you might go up to a maximum 1500 psi. The nozzle on some hand-held wands is rotated to vary the spray pattern from round to fan-shape, and sliding the nozzle in and out varies the size and intensity of the water stream. Be sure to read the operating instructions of the power-washer or have a rental unit demonstrated.

Not sure you want to do the job? Click Home Advisor, a free referral service that connects homeowners with prescreened local contractors, and type "power wash services" in their Find Pro search box.

  • Step 1 : Prepare the surface

    To prevent a powerful blast of water damaging siding, prepare the surface by taping (with waterproof tape) plastic garbage bags over air conditioners, exterior wall vents and receptacles and kill the power. Remove the tape immediately after washing or it may become a permanent decoration. Close and lock all windows, and close all doors.

  • Step 2 : Protect plants and shrubbery

    Use a garden hose to soak the plantings surrounding the house and then cover them with dropcloths. Remove the cover-ups as soon as possible after spraying with the power washer. Use drop cloths or large sheets of cardboard to catch paint chips that fall off.

  • Step 3 : Protect yourself

    Dress for a rainy day and wear rain gear, especially boots and safety goggles.

  • Step 4 : Practice using the sprayer

    To test the pressure adjustment of the unit, begin spraying on an inconspicuous area. Practice your spray angle by holding the sprayer to the surface until you get the even results you want. Overlap passes for even cleaning. Don't swing the wand in an arc; you will get uneven results because you are closer to the surface in the center of the arc.

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