Size of Shower Compartment

Among the rules related to shower booths when designing houses, the 30" clearance is familiar, but it is not clear whether the 30" rule is based on the curb of the floor or the glass partition when designing a compact bathroom.

Referring to the original code, 2019 California Plumbing Code.

408.6 Shower Compartments

Shower compartments, regardless of shape, shall have a minimum finished interior of 1024 square inches (0.6606 m2) and shall also be capable of encompassing a 30 inch (762 mm) circle. The minimum required area and dimensions shall be measured at a height equal to the top of the threshold and a point tangent to its centerline. The area and dimensions shall be maintained to a point of not less than 70 inches (1778 mm) above the shower drain outlet with no protrusions other than the fixture valve or valves, showerheads, soap dishes, shelves, and safety grab bars, or rails. Fold-down seats in accessible shower stalls shall be permitted to protrude into the 30 inch (762 mm) circle.

As explained in the original code, curbs are no exception like plumbing fixtures and other accessories. In other words, 30" clearance must be secured from the floor to the 70" height section.

An illustrated sketch is attached for an easier reference. (The graphic source is the Residential Bathroom Requirements of the city of Livermore, CA)

In addition, to explain the regulations related to curb and door, a curb is required at a shower. It shall be a minimum of 1" above the shower floor and between 2" and 9" above the top of the drain. Any doors shall swing out of enclosure have a clear opening of 22" minimum.

I hope this post will be helpful to people who want to add even a little bit of professionalism to their work and to organize their work completely by applying the correct code requirements.