How to soft wash house siding

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In the video, Brian soft washes painted lap siding with a cordless cleaner and a soap attachment. Low pressure cleans without forcing water behind the siding.

Video by Brian Huie on YouTube. Watch on YouTube

How often
Every 2 years (Brian's schedule)
Video
57 seconds

How often should siding be washed?

Brian's schedule is every 2 years. James Hardie suggests hosing down its fiber cement siding every 6 to 12 months, and paint and vinyl siding makers say to clean as needed.

Why soft wash instead of pressure wash?

James Hardie says not to use a high-pressure washer; use a low-pressure hose and a soft nonmetal brush. If a pressure washer is used on its siding, keep it under 1,500 psi with a wide fan tip at least 6 feet from the wall. On vinyl, never aim the spray upward, which can force water behind the panels.

How do you wash siding?

  1. Check for mildew first; it can look like dirt and grows where surfaces stay damp or shaded.
  2. Pick the mildest cleaner that works: plain water, then mild dish soap, then a mildew cleaner made for the siding. Test it in a hidden spot.
  3. Wash small sections with a soft brush. James Hardie says top to bottom for its siding; the vinyl siding association says bottom to top to prevent streaks.
  4. Rinse thoroughly and never let cleaner dry on the siding.

Safety notes

  • Follow the siding maker on chemicals: James Hardie says no bleach or acid, while Sherwin-Williams allows a bleach solution on painted surfaces with mildew. Never mix bleach with ammonia or detergent.
  • Wear eye protection and gloves, and keep water away from windows, doors, wiring and plumbing.

Seattle-area notes

Seattle Public Utilities allows washing a single-family home with plain water. If soap, detergent or bleach is used, the wash water must be collected or sent to the sanitary sewer, not the storm drain, and cleaning chemicals should not go on during rain.

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Sources

  1. James Hardie: tips for cleaning your siding
  2. Polymeric Exterior Products Association: vinyl siding care
  3. Sherwin-Williams: mildew
  4. James Hardie Technical Bulletin USTB 20: cleaning siding (PDF)
  5. Seattle Public Utilities: exterior property maintenance and stormwater

Checked October 2026. Manufacturer instructions for a specific model come first. General information, not a substitute for a licensed professional.

From the Home Care Advice by Brian Huie, a principal broker and Realtor with Compass in Seattle.