What size should a vent system be adjusted to for multi-story buildings?

In multi-story buildings, the vent system should be adjusted as a stack vent to ensure proper air circulation and drainage throughout the plumbing system. A stack vent is a vertical pipe that extends from the highest point of the drainage system and allows for the equalization of pressure within the system as wastewater flows down. This is crucial in preventing siphoning of traps and maintaining a good flow of wastewater.

Using a stack vent in a multi-story building helps accommodate the increased height and complexity of the system, ensuring that every fixture has adequate venting, which is essential for the prevention of negative pressure in the system that can lead to drainage issues. It also allows for the proper venting of gases and odors, contributing to overall system efficiency and safety.

The other suggested methods, such as adjusting to an individual vent or based on the lowest fixture, do not provide the same level of assurance in a multi-story context, where variations in pressure and drainage demands can create complications that a stack vent effectively addresses. Regulations regarding property lines are also important but pertain more to installation standards rather than the sizing of the vent system itself.