So to vent this bathroom for the shortest distance I would have to make a hole in the main roof line then through the garage roof to vent this fan. Or run the flexible ductwork about 15 feet up the pitch of the
pressure and/or vacuum must not exceed 1-inch of water column. Pressure can be exerted against the trap seal by the slug of air being pushed ahead of a sudden larger flow, like when a toilet is flushed, or even by wind as it travels across a roof vent. The roof ...