Rough plumbing involves installing all of the water lines, sewer lines and bathtubs. Tubs are normally installed early because:
- One-piece shower-and-tub units are big and often cannot be maneuvered into place later in the construction cycle. They also frequently "change size" -- that is, the size drawn on the plans and the size delivered often differ significantly.
- A full tub is heavy. Therefore, the tub is installed and filled so that the frame can settle quickly. This step prevents cracked walls and tile the first time someone uses the tub.
Typically, rough plumbing involves installing all sewer lines and vents as well as all water supply lines for each fixture.