What is the minimum extension required for vent pipes above a roof used for non-weather protection purposes?

For vent pipes that extend above a roof primarily for non-weather protection purposes, the minimum extension required is typically 7 feet. This standard is established to ensure that the vent pipe can effectively function without any obstructions from the roof itself and to promote proper ventilation of the plumbing system. The height is crucial because it helps to minimize the risk of any potential exhaust backdrafts affecting the home’s air quality. By extending the vent pipe a minimum of 7 feet above the roofline, it's ensured that any exhaust gases can disperse effectively into the atmosphere, reducing the likelihood of dangerous fumes re-entering the building.

The other options do not meet this minimum requirement, which is designed to maintain a safe and functional venting system. Lower heights could compromise the venting effectiveness and could lead to code violations, making the correct 7-foot height essential for proper health, safety, and compliance with relevant building codes.