A prefabricated bathroom assembly and methods for its manufacture and installation are disclosed. The prefabricated bathroom assembly preferably includes at least some of the same or similar building materials (e.g., stud construction, tile finishing, wallpaper, and floor-mounted toilets) traditionally used for on-site construction, in order to provide maximal aesthetic quality and comfort as well as the ability for a purchaser to customize the design. The bathroom assembly is preferably pre-fabricated substantially in its entirety off-site for delivery to the site in a single piece, and needing only fastening into place and connection to utilities at the site in order to complete the installation. In an embodiment, a prefabricated bathroom with a low-profile floor is provided that complies with applicable provisions of the Americans with Disabilities Act ("ADA"). In another embodiment, Computer Aided Design ("CAD") technology is used in the design of the prefabricated bathroom assembly.