UPC Pipe Sizing Guide

The Uniform Plumbing Code (UPC) is widely adopted in the western United States. Its pipe sizing approach parallels the IPC but uses different fixture unit values and separate tables for drainage (Table 703.2) and building drains (Appendix C Tables C304.2 and C304.3). Plumbing Booster fully supports UPC for both water supply and drainage calculations.

UPC water supply pipe sizing: 1. **Sum WSFU** using UPC fixture unit tables (separate cold/hot values per fixture type). 2. **Convert WSFU to GPM** using UPC conversion tables with system-type-specific values. 3. **Select pipe size** from UPC water pipe sizing tables based on flow and available pressure. 4. **Verify velocity** against UPC-recommended limits. UPC drainage pipe sizing: 1. **Sum Drainage Fixture Units (DFU)** per pipe segment. 2. **Determine pipe size** from Table 703.2 (maximum unit loading and maximum length). 3. **Check slope** - UPC specifies 1/4" per foot for pipes <3", 1/8" per foot for pipes >=3". 4. **Size building drain** using Appendix C Table C304.2 based on slope and DFU.

Key UPC tables: - **Table 703.2** — Maximum unit loading and maximum length of drainage and vent piping - **Appendix C Table C304.2** — Building drains and building sewers - **Appendix C Table C304.3** — Horizontal fixture branches and stacks - **UPC WSFU tables** — Water supply fixture unit values

A building drain serving 35 DFU at 1/4" per foot slope: From Table 703.2: 35 DFU on horizontal drainage piping requires a minimum 3" pipe (max 35 units at 3" horizontal). From Appendix C Table C304.2 at 1/4" slope: 3" pipe allows 42 DFU - sufficient. If the slope were 1/8" per foot, 3" pipe allows only 20 DFU - insufficient. The software would upsize to 4" (180 DFU at 1/8" slope).

Select "UPC" as the plumbing code in System Structure Configuration. All fixture tables, WSFU values, drainage tables, and pipe sizing automatically switch to UPC data. The Drainage module uses UPC Table 703.2 and Appendix C tables for pipe sizing and slope compliance.