I had a problem with a leak around the sewer vent on my Bigfoot. The ABS pipe exits the roof and there was a gap around it. The vent assembly consists of a cone that is screwed down to the roof fiberglass and a silly cap that can easily be knocked off. When the cap is gone, rain enters and fills the cone until it can run down along the vent pipe. My solution was to clean all of the moss and water out of the cone, dry it all out, and then spray foam the gap around the vent pipe. I thought about filling the whole cone with foam sealer, but decided instead to drill a drain hole in the cone at the low corner. I can always fill the entire cone later if needed. I recently found a more rugged vent cap that is held in with spring wire. The second vent, for the gray water venting, was also modified likewise.
Oh. The water leak ruined the wood that supported the jack at the rear corner. But that is another story.
