Plumbing Reference Charts

ABOUT THESE CHARTS

These charts cover the look-ups plumbers, gas fitters, and MEP engineers make while sizing a system: drainage and water supply fixture units per fixture, drain, stack, and building-drain sizes from total DFU by slope, vent sizing with trap-to-vent distances, water pipe and meter sizing from WSFU and developed length, minimum trap and slope requirements, and fixture flow and consumption limits.

On the fuel-gas and specialty side there are natural gas, CSST, and propane pipe sizing, gas appliance BTU demand, storm drain and roof leader sizing by rainfall, grease interceptor sizing, compressed air pipe sizing, the medical gas reference, hot water recirculation return sizing, and water hammer arrestor sizing by PDI unit.

Model plumbing codes disagree more than electrical ones do, so every chart keeps IPC and UPC values separate and labeled — never averaged or merged — and cites the governing section of each. Gas sizing follows NFPA 54/58; engineering and manufacturer values (CSST capacity, compressed air, grease interceptors) are labeled as such and sent back to the AHJ and the manufacturer data. As always, the adopted code and local amendments govern — confirm against the edition your inspector enforces.