Which of the following is NOT an acceptable installation for vent pipes according to plumbing codes?

Vent pipes play a crucial role in plumbing systems by allowing air to enter the drainage system, helping to prevent pressure buildup and enabling wastewater to flow smoothly. For a vent pipe installation to be code-compliant, it must follow specific guidelines regarding where and how it terminates.

Terminating just below the roofline is not an acceptable installation. This is because vents need to extend above the roofline to prevent any potential blockages from snow, ice, or debris and to allow gases to safely disperse into the atmosphere away from any building openings. By terminating below the roofline, there's a risk that harmful gases, such as sewer gases, could escape and enter the building or accumulate near the roof where they could be harmful to inhabitants.

In comparison, extending through the wall is acceptable as it allows for proper ventilation of the system when correctly installed. Extending 6 inches above the roof meets code requirements for venting, ensuring that the opening is high enough to avoid potential issues. Additionally, vent pipes can be installed to extend straight upwards, which is the most straightforward method of ensuring an effective ventilation system.