How to Clean Windows with a Pressure Washer

Washing your windows with a pressure washer is fast, and the wand allows you to reach second-story windows without having to climb all the way to the roof edge. Counterbalancing these advantages -- and possibly outweighing them -- are the dangers of cracking glass or loosening window putty with the high pressure water and the fact that pressure washing often doesn't do that good a job. If pressure washing is for you, be safe; use low pressure and a wide spray pattern.

Pros Don't Do It

Contractors that specialize in pressure washing siding and include window cleaning as part of their services usually advertise hand-cleaning for the windows. The best way to clean a window is to use a foam applicator to apply soapy water and a squeegee to wipe off the water, taking care of streaks with a chamois or microfiber cloth.

If you want to do your windows quickly as part of a general exterior house-washing project, though, do the windows separately from the siding. They require different spray techniques. It's almost worth using different machines -- a gas-powered high-pressure one for siding and an electric one with a detergent reservoir for windows.

Requirements for Window Pressure Washing

  • Low pressure preferably under 2,000 psi.
  • Wide spray pattern: 40 to 65 degrees.
  • Ability to mix cleaning solution and water in the spray.

Window Washing Procedure

Step 1

Set up the power washer by connecting it to a source of water. Before you start it or turn it on, set the nozzle to it's widest pattern or screw on a 40- or 65-degree nozzle. Forty-degree power washer nozzles are white, and 65-degree ones are black. Adjust the pressure to a value between 1,500 and 2,000 psi, and test the spray on a basement or garage window. Spray obliquely -- never perpendicular to the window.

Step 2

Fill the soap reservoir with a detergent recommended by the pressure washer manufacturer. The detergent must be safe for your window frame material. If your power washer doesn't have a soap dispenser, and you want to get the windows as clean as possible, consider washing them quickly using a suitable cleaning solution and a sponge applicator, and rinsing with the power washer.

Step 3

Keep the tip of the sprayer a safe distance from the window, depending on the pressure. The spray should strike the window at no steeper than about a 30-degree angle. As much as possible, spray from the edge of the pane toward the center; avoid getting spray under the window putty, or the putty may simply fly off.

Step 4

Turn off the soap dispenser and spray the window with clear water immediately after washing it and before the cleaning solution has a chance to dry.

Chris Deziel

Chris Deziel

Chris Deziel has a bachelor's degree in physics and a master's degree in humanities. Besides having an abiding interest in popular science, Deziel has been active in the building and home design trades since 1975. As a landscape builder, he helped establish two gardening companies.