About Pressure Washers for Roof Cleaning
Soft-wash systems run at under 30 bar with a long lance and apply a biocide that kills moss over weeks. Top picks include the Karcher SC4 and dedicated soft-wash systems from SpinAclean or Wash-IT.
If you must use a pressure washer on a roof, stay at low pressure (under 100 bar), use a wide fan nozzle, and never spray uphill or against the laps.
For severely mossed roofs, scrape first with a roof scraper, soft-wash with biocide, then leave to die back over several months. Pressure washing alone is rarely the right answer.