[rhagfo]

Originally Posted by Steveo57

I would agree with JRTJH. I doubt it's cut too short. They lay the roofing membrane over the whole trailer and then just cut the holes where needed. The chances of leakage uniformally at each corner are slim. The roof vent frame being all metal is going to get covered in condensation and then run down into the ceiling.

Take a shower with the trim off and the vent closed as you have been and see what it looks like.

I agree CONDENSATION that frame is aluminum closed up trailer condensation!!!!
#1 get an electric dehumidifier run it at a setting of less than 40%, open vent and run the entire time you shower, dry off and dress.
Does your range hood vent outside? Do you run it the entire time you are cooking?? Cooking creates a lot of humidity.