Originally Posted by TeamIdaho
We have missing trim that should run horizontally (we bought this last year, used) and vertical trim that is dry and cracked and needs replaced. I am wondering -- is this stuff just cosmetic or does it prevent leaks? I bought the trim and am just waiting on the sealant but I do wonder if this is only for looks?
In my experience (2 old trailers) they don't do much in the roof gutter (horizontal) runs. The verticals could be an exception.
The aluminum walls of the trailer cover a 1x2 that runs around the edge of the roof. The 1x2 is covered by the roof decking. The roof membrane laps over the wall, behind the roof gutter. A 1" wide strip of butyl tape (sticky, non-hardening caulk) is between the roof gutter and the membrane. The butyl tape seems to stop any water intrusion.
Where the vertical channels curve up to horizontal at the front and back seems to be a spot to watch. Water could puddle around the screw heads at the top and intrude.
The real spot to watch can't be protected by vinyl channel inserts. It is where the awning brackets bridge the rain gutter and are screwed right through the vinyl insert or just above it. There seems to be no way to stop intrusion there. The water ruins the 1x2 rim band and then wicks up into the roof decking. Both our trailers have semicircular soft spots in the roof decking, centered on the awning brackets.