We live in a new modular home in Maine. The kitchen range hood vent runs horizontally in the attic following the pitch of the roof and then vents vertically through the roof. The pipe is uninsulated and not sealed. In the winter, moist air from the kitchen condenses staining the roof sheathing and leaking through the joints and drips down onto the knee wall framing and wall of attic. Our plan is to rerun the pipe at a right angle for 22 feet and exit through the gable end, insulating the pipe and providing a slight downward pitch for the condensation to run towards the gable end. Is this a good plan? Any suggestions? How would we seal off the existing opening in the roof.