Who specifies the rough-in dimensions for a particular fixture?

The correct choice is the manufacturer. Manufacturers of plumbing fixtures prepare specifications that include detailed rough-in dimensions. These dimensions are crucial for ensuring that the fixtures can be properly installed into the existing plumbing system. The specifications account for various factors, such as the type of plumbing connections required, the space needed for the fixture, and other installation requirements. By providing these dimensions, the manufacturer helps avoid installation issues and ensures that the fixture operates correctly once in place.

Craftsmen and contractors play important roles in the installation process, but they typically rely on the specifications provided by the manufacturer when determining how to install a fixture properly. The shop foreman may oversee the work and ensure that specifications are followed, but they do not typically set the dimensions themselves.