Exterior Mildew Removal

Exterior surfaces are not immune to mildew, the early stages of mold development.

Use a bleach solution to remove mildew from exterior areasUse a bleach solution to remove mildew from exterior areas
Mildew is a growth that develops in moist, dark and wet conditions including on house siding, outdoor chairs and even on concrete. If left to grow, mildew turns into larger mold spores, and can take over exterior surfaces and eventually enter interior structures. You can remove mildew from exterior surfaces and items, using a cleaning solution, without damaging the surface underneath the mildew.

Place drop cloths or plastic on the concrete, grass or ground below the exterior area or item containing mildew to keep the bleach solution from affecting the area.

Sweep the area or item containing mildew with a broom or rag to remove any loose mildew, dust and dirt.

Mix 1 qt. of household bleach and 3 qts. of warm water in a bucket. Wear rubber gloves, a long-sleeved shirt and long pants to protect yourself from the mildew and to keep the bleach solution off of your skin.

Stir the bleach mixture with a soft-bristle scrub brush. Scrub the mildew-covered area or item with the bleach solution. Avoid splashing the bleach solution on any uncovered grass, shrubbery or areas not containing mildew.

Reapply bleach solution to the scrub brush as needed. Continue cleaning the area or item until it is mildew free.

Spray the area or item with water from a water hose once you have removed the mildew. Let the area or item air dry.

Dispose of the drop cloths or plastic in your home's trash can once the exterior area or item is dry.

Things You Will Need

  • Drop cloths or plastic
  • Broom or rag
  • Household bleach
  • Warm water
  • Bucket
  • Rubber gloves
  • Long-sleeved shirt
  • Long pants
  • Soft-bristle scrub brush
  • Water hose with sprayer
  • Trisodium phosphate (TSP)
  • Powdered laundry detergent


  • If the mildew buildup on the exterior area or item is heavy, add 2/3 cup of trisodium phosphate and 1/3 cup powdered laundry detergent to the bleach solution to breakup the large amount of mildew.

About the Author

Nick Davis is a freelance writer specializing in technical, travel and entertainment articles. He holds a bachelor's degree in journalism from the University of Memphis and an associate degree in computer information systems from the State Technical Institute at Memphis. His work has appeared in "Elite Memphis" and "The Daily Helmsman" in Memphis, Tenn. He is currently living in Albuquerque, N.M.