To know the minimum size of a building drain, which reference should you follow?

To determine the minimum size of a building drain, it is essential to accurately assess the total drainage fixture units. The correct approach involves first calculating the total number of fixture units serving the building. Once this figure is obtained, referencing the Uniform Plumbing Code (UPC) allows for the precise determination of the appropriate drain size based on that total.

This method aligns with established standards in plumbing, ensuring that the drain is adequately sized to handle the expected flow and minimize issues such as backups or blockages. The UPC provides a reliable guideline for converting fixture units into pipe sizes, making it a trusted resource for plumbing professionals.

Other options may suggest different calculations or methods that do not adhere strictly to the standards set by the UPC, which could result in an incorrectly sized drain that doesn't meet the necessary performance criteria. By following the established process of calculating total fixture units and consulting the UPC, you ensure compliance and efficiency in the plumbing system design.