Flat Roof Solutions < --- LINK
When I actually get to building the camper next spring, it's going to have a flat roof. Flat roofs will leak unless completely sealed. Had considered slathering layers of roofing tar over the plywood then adding some asphalt roll roofing, but that adds extra weight and if the roll roofing isn't laid down perfectly, it will peel, bunch up, or simple get air pockets that look weird.
You got a rat building a nest under that roof, Charlotte?
Googled the term ''flat roof'' and found www.flatroofsolutions.com . Amazingly, their product isn't that expensive. The black on black rubber has a 25 year guarantee, too.
Basically, you have to sand the plywood smooth and round the exterior edges of the plywood a bit then sweep off all dust, dirt, and grit. The plywood has to be bone dry. They recommend 5/8" plywood, so the roofing rubber must have some weight to it. You use their adhesive to glue the rubber roof and let it set. Has to be done during warmer weather because the adhesive only works in continuous temperatures of fifty degrees Fahrenheit or warmer. With a little aluminum trim around the edges to keep it from peeling up, the roof situation might be solved.
My camper roof will be 14 feet long and six to eight feet wide. I would have enough rubber left over to seal around the edges when the camper meets the trailer floor. Sounds good enough to waterproof the small area under the shower, too.
Maybe they will have a sale next spring. Oh, yeah. ; )