Newer homes are often plumbed to allow easy installation of a basement bathroom. These bathroom “rough-ins” usually include drains for a toilet, a tub or shower, and a sink. A 4-in.-round PVC sewer line, capped at floor level or a bit above, accomodates a toilet. A drain and vent stack (usually 2 in.) running from the floor to the ceiling serves the sink. Nearby should be a roughly 12-in. square plastic cover set in the floor. It protects a drain line set below the concrete for a bathtub or shower. Some tub rough-ins are thinly covered with concrete.You can find these by tapping on the surface of the concrete with a hammer. Solid concrete has a flat, dull sound. As you tap, you’ll hear the recess where the rough-in hides as a change in pitch. Older rough-ins may simply be boxed by 2x4s, exposing a small square area of sand covering the capped drain line.
If you lack these rough-ins, or want them in a different spot than at present, call in a professional plumber. Jackhammering concrete to install or move drains is hard work, and you’ll want to make sure it is done right. Once the basics are in place, there’s plenty of installation you can do.