The highest fixture connected to a waste or soil stack not requiring a re-vent is said to be _____________________.

The highest fixture connected to a waste or soil stack that does not require a re-vent is referred to as stack vented. This terminology indicates that the fixture can discharge wastewater without needing additional venting to prevent siphoning, which can cause drainage issues.

In a stack vented system, the vertical orientation of the stack itself serves to allow air to enter, preventing a vacuum that could impede drainage and ensure proper flow of wastewater. The stack venting is crucial for maintaining the necessary air pressure within the plumbing system for effective wastewater evacuation.

Understanding the stack venting concept is particularly important for plumbers and those working with plumbing codes, as it influences the design and layout of drainage systems in buildings. A fixture that is properly stack vented allows for efficient waste removal without the need for additional venting measures, thus simplifying installation and potentially reducing material costs.