Ceiling ventilation fan
I want to install a ceiling ventilation fan. CampingWorld has them but the install guy says that cutting a hole in the bus is different than cutting a hole in an RV since the RV ceiling is a single ply but the bus roof is two ply (out skin and interior roof). If so, do I need some type of flashing for the inside? How thick is the layer between the two plys of the school bus? Does anyone make a fan specifically for school bus? It is an 87 BlueBird on a Chevy C-60. Thanks, as always.