For a 7/12 pitched roof, what is the minimum height of a main vent?

The minimum height of a main vent on a 7/12 pitched roof is indeed 1 foot 3 inches. This dimension is determined by local plumbing codes and is crucial for ensuring proper ventilation of plumbing systems. The height is designed to prevent any potential backdraft or interference from wind-driven rain and snow, especially on sloped roofs where the angle can affect the flow of air up the vent.

For a 7/12 pitch, which corresponds to a roof that rises 7 inches for every 12 inches of run, 1 foot 3 inches provides adequate clearance above the roofline. This allows for efficient venting while minimizing the risk of water entering the vent pipe, which could occur if it were too short. Following these guidelines helps to maintain proper pressure balance in the plumbing system and supports the efficient operation of drainage systems.