RV type
If a Class C is leaking, start at the cab-over. The bunk overhang joins the chassis cab at a seam that flexes constantly and takes wind-driven rain head-on.
We see cab-over rot on Class C coaches more than any other single failure. Caught early it's a reseal; left alone it becomes structural work on the overhang itself.
We'll get on the roof, photograph what we find, and give you a fixed written price. No charge and no pressure.