Sanitary Drain DFU Sizing
Total drainage fixture units from a fixture list and the minimum pipe size for a horizontal branch, vertical stack, or building drain. Per IPC 2021 §710 with Table 709.1 DFU values.
Formula and source
total DFU = sum(fixture count × DFU value). Minimum pipe size = smallest size whose table maximum ≥ total DFU: horizontal branch and stack per IPC Table 710.1(2); building drain per IPC Table 710.1(1) (slope-dependent).
IPC 2021 (International Plumbing Code). Section 710; DFU values per IPC Table 709.1; capacities per Tables 710.1(1) and 710.1(2).
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