Disclosed herein is a prefabricated shower base. The shower base has a funnelled floor with a drain recess located in it. The drain recess has a bottom wall disposed along a first plane. A perimeter wall surrounds the funnelled floor and has a top perimeter wall surface disposed along a second plane, which defines a shower base threshold. The perimeter wall has a bottom perimeter wall surface disposed along a third plane. The first plane is located below the third plane.