Most roofing manufacturers recognize soft washing as a safe cleaning method when done correctly, but whether it affects the warranty depends on the manufacturer’s specific guidelines. Here are the key points regarding roofing manufacturers' recommendations and warranty concerns:

1. Manufacturer Recommendations on Soft Washing

• Asphalt Shingle Roofs (e.g., GAF, Owens Corning, CertainTeed)Many manufacturers, including GAF and ARMA (Asphalt Roofing Manufacturers Association), recommend using a soft wash method instead of pressure washing.
  They suggest using a mix of sodium hypochlorite (bleach) and water with a surfactant to remove algae, moss, and mildew.
  Rinsing thoroughly after the application is crucial to avoid damage.
  
• Metal RoofsSome metal roofing manufacturers allow soft washing, but they caution against prolonged chemical exposure.
  It’s essential to use a low-pressure application and rinse thoroughly to avoid damage to coatings.
  
• Tile and Slate RoofsMany tile and slate roof manufacturers approve soft washing but emphasize the importance of avoiding harsh chemicals that can break down protective coatings.
  

2. Will Soft Washing Void the Warranty?

• Using High Pressure (Not Soft Wash)If high-pressure washing is used instead of soft washing, it will likely void the warranty, as it can remove granules from shingles or damage coatings.
  
• Incorrect Chemical RatiosSome manufacturers specify the allowed concentration of sodium hypochlorite (usually no more than 50% diluted with water).
  
• Not Following Manufacturer GuidelinesIf the manufacturer has a specific cleaning procedure and it’s not followed, the warranty may be voided.
  Some require professional cleaning or certified contractors for maintenance.
  

Best Practices to Protect the Warranty

• Check the manufacturer's website or documentation for cleaning guidelines.
• Use a low-pressure soft wash system (under 100 PSI).
• Use the correct sodium hypochlorite dilution and a surfactant to help it cling without excessive runoff.
• Rinse thoroughly to remove chemical residue.
• Document the process (before and after photos, chemical dilution used) in case of future warranty claims.