Curbless Shower Retrofit

Last October, our company undertook a remodeling job in Provincetown, Mass., that included a complete makeover of the kitchen and two bathrooms. Part of this makeover involved installing new floor tile and integrating curbless, or barrier-free, showers in both bathrooms. The floor tile came flush with the hardwood flooring outside the bathroom doors, and the client wanted to maintain perfectly even floor planes. Somehow we had to find a way to establish a drainage slope in the showers without adding to the original floor thickness.

A curbless shower requires one of several possible designs for creating a 1/4:12-inch drainage slope. It was clear we couldn’t build up the subfloor, and we were reluctant to reconfigure the floor joists under the pan. This is fairly easy to do in new construction but much more complicated in an existing home, especially on this job: The floor...