For SURE do not walk on thin slate roofing.
As far as roof cleaning chemical, we suggest only Sodium Hypochlorite and water.
Skip any detergent/TSP, etc.

Apple Non Pressure Roof Cleaning Tampa
813 655 8777
Non Pressure Roof Cleaning for
Pinellas, Pasco, Hernando, Polk, Manatee, Hillsborough County, FL.