How far above a roof should a vent pipe terminate?

The correct termination height for a vent pipe above a roof is established to ensure proper function and to avoid potential issues with drainage and ventilation. Vent pipes must extend at least 6 inches above the roof to prevent any possible obstructions that could lead to back pressure or siphoning of the plumbing traps. This height also helps to ensure that the vent is clear of any snow or debris that could accumulate at roof level, maintaining proper airflow and preventing odors from entering the building.

Additionally, this standard allows for adequate air pressure to be maintained in the plumbing system while ensuring that any gases vented from the system are safely released above the roofline. This practice is critical for ensuring the safety and efficiency of the plumbing system. Other heights, such as 4 inches, are insufficient for these purposes and could lead to problems such as venting obstruction or issues with drainage.