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Plumbing Reference

Pipe sizing · Fixture units · Rough-in dims · Materials

Rough-In Dimensions

Toilet

  • •Flange center: 12" from finished wall (12" rough-in standard)
  • •Supply stub: 6" off floor, 6" to left of center
  • •Drain: 3" or 4" closet flange

Lavatory / Pedestal Sink

  • •Drain center: 17"–19" AFF (center of drain)
  • •Supply stubs: 21" AFF, 4" apart (hot left, cold right)
  • •P-trap: 16"–18" AFF (center)

Kitchen Sink

  • •Supply stubs: 20" AFF, centered under cabinet
  • •Drain center: to align with cabinet knockout, ~16" AFF
  • •Standard knockout height: 16"–18" AFF

Bathtub (alcove)

  • •Drain offset: 14"–16" from head wall (verify tub spec)
  • •Supply valve: 28" AFF, centered
  • •Spout: 4" AFF, centered
  • •Overflow: typically 16"–18" from floor

Shower

  • •Valve: 48" AFF (center of valve)
  • •Showerhead: 78"–80" AFF
  • •Drain: centered in shower floor
  • •Supply: 1/2" minimum to valve

Water Heater

  • •Seismic strap required top 1/3 and bottom 1/3
  • •18" clearance from ignition source (gas, combustibles)
  • •Supply / return: 3/4" recommended
  • •T&P relief valve discharge: terminate 6" AFF or to outside

AFF = Above Finished Floor. Always verify dimensions against the specific fixture's installation sheet before roughing in.