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 doesn't always do the best 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.
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If you want to do your windows quickly as part of a general exterior house-washing project, 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.
If you choose to use a pressure washer for your windows, follow these guidelines:
- Low pressure preferably under 2,000 psi
- Wide spray pattern: 40 to 65 degrees
- Ability to mix cleaning solution and water in the spray
How to Wash Windows With a Pressure Washer
Step 1: Inspect the Windows
Ensure your windows are in good condition before deciding to pressure wash them. If your windows have wooden frames, inspect the window putty where the glass meets the frame to ensure it's in good condition. You'll also want to look for issues with the caulking along the window frame and siding as well as the weather stripping to avoid having water spray inside your home.
Step 2: Prepare the Pressure Washer
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 its 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.
If your windows are under warranty, check with the manufacturer or supplier/installer to confirm that pressure washing won't void the warranty.
Step 3: Add the Detergent
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, consider washing them quickly using a suitable cleaning solution and a sponge applicator and rinsing with the power washer.
Many cleaning solutions are toxic to plants. To prevent damage from overspray, wet outdoor plants thoroughly, then cover them with plastic before washing your windows. After washing, remove the plastic and wet the plants again.
Step 4: Get the Right Positioning
Keep the tip of the sprayer a safe distance from the window. 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 5: Spray With Clean Water
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.
Step 6: Wash Second Story Windows
Switch to a second story nozzle or extension wand to pressure wash your upper-floor windows. Using an extension ladder to power wash second-story windows is very dangerous and shouldn't be done.