HVAC Code Practice Test Practice Exam

When a Type B vent ends above a roof, the exhaust must stay clear of openings that could draw it back into the building. The distance you must keep from the lowest discharge opening depends on the roof’s pitch; with a steep 12/12 roof, the vent plume is more likely to reach lower openings, so the clearance is increased. The required minimum is four feet above the lowest discharge opening. This four-foot buffer helps ensure the exhaust doesn’t impinge on doors, windows, or other openings and get recirculated into the building, even in wind conditions. The smaller distances would not provide enough separation on a steep roof, while five feet is simply more than the minimum needed.