How should plumbing vents be terminated above the roof?

Plumbing vents should be terminated at least 6 inches above the roof surface to ensure proper ventilation and to prevent any potential blockage from snow, ice, or other debris. This height helps to create an adequate air flow into the plumbing system, which is necessary for proper drainage and to avoid negative pressure conditions that could lead fumes to enter the living spaces.

Additionally, terminating the vent above a certain height is crucial for health and safety reasons, protecting occupants from harmful gases that could escape from the plumbing system. Vent pipes must be high enough to allow gases to disperse effectively into the atmosphere.

While options suggesting other heights may also address certain scenarios, they do not provide the same balance of effectiveness and safety. For instance, 3 inches above the roof may not provide sufficient clearance in some weather conditions, while heights higher than 6 inches may be unnecessarily excessive in most situations. Therefore, the established standard for vent termination is set at a minimum of 6 inches above the roof surface.