Are you sure you have a fiberglass or a TPO roof?
I have a TPO roof, Thermoplastic Polyolefin (TPO) is a single-ply reflective roofing membrane made from polyprophylene and ethylene-propylene rubber polymerized together. It is typically installed in a fully adhered or mechanically attached system, allowing the white membrane to remain exposed throughout the life of the roof.
I called Dicor, who supposedly made the roof for Coachmen, and they said to only wash it a couple times a year and never re-coat it. They said re-coating them breaks down the material.
Retired Army, Disabled Veteran
Wife, me, and 2006 Coachman Cross Country 372DS makes three, Demco Kar Kaddy SS