A 10-story stacked restroom core case study — per-floor fixture unit takeoff, a domestic water riser read off the flushometer Hunter's Curve, DWV stacks split by restroom instead of by floor zone, and a worked water-conservation savings calculation from low-flow fixture selection.
The project brief: a 10-story office building stacks an identical men's/women's restroom core on every floor. It's the plumbing engineer's cleanest sizing problem and easiest trap — every floor's fixture count is identical, but a straight per-floor multiply only stays valid through the fixture unit takeoff itself, not through Hunter's Curve or stack diameter selection.
This module walks the whole design the way a real plumbing engineer would: the flush-valve fixture unit takeoff per floor and building-wide, a riser sized off the flushometer demand curve that only changes size where cumulative demand crosses a capacity threshold, a men's-stack/women's-stack DWV split instead of one oversized single stack, and a worked gallons-per-day comparison showing what WaterSense fixture selection actually saves. The full worked numbers, complete bill of materials, and finished design reasoning are part of the unlocked module below.