Wondering the same thing. I have a 2013 Heritage Glen. I recently washed and applied a UV inhibitor to the roof. The seals were still all very pliable and looked good.
I want to stay out in front of this so there’s no issues down the road.
I do ours 2-3 times a year, but ours is stored outside when not in use. If we kept it inside or at least under roof, I'd probably just do once before camping season started.
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Cut it 3 times and it's still too short...
My trailer is stored outside 100% of the time. I wash the roof twice a year, spring (part of my de-winterizing) and late fall (part of my winterizing).
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"Do, or do not, there is no try." - Yoda