The term “rough in” refers to the installation of a building’s electrical and plumbing services in the wall cavities just before lining the walls with plasterboard. Holes are usually cut in strategic points in the wall studs through which the plumbing and drainage pipes will run through. Setting the rough-in is the final step of connecting a tub, sink, or toilet, after which you can finish your walls.
The height to the rough-in is measured from the subfloor (in new constructions) or from the finish floor (in remodeling projects) to the centre of the pipe fitting, measured along the centerline (an imaginary vertical line for reference purposes).
Sink Rough-in Dimensions
- Drain pipe – Hole positioned 16 – 20 inches above the finished floor measured along the centerline Supply lines – Two holes are needed: the first one is positioned 4 inches to the right of the centerline, and the other one 4 inches to the left of the centerline. Both are positioned about 2 – 3 inches above the drain pipe.
- Sink placement – The sink should be positioned about 31 inches above a finished floor, measured vertically up to the rim of the sink
Toilet rough-in Dimensions
- Supply Line – One hole positioned between 5 and 10 inches above the finished floor. The supply line should be off-set from the centerline by 5 inches.
- Discharge hole – This hole should be off-set from the wall framing by 12.5 inches, positioned along the centerline.
Tub rough-in dimensions
- Shower Stub – Positioned at 80 inches from the floor, this is the highest point where the shower nozzle will be attached. This is along the centerline.
- Tub spout/stub – Positioned 26 – 35 inches from the floor along the centerline
- Faucets – Positioned 10 inches above the tub spout. One faucet is placed 4 inches to the left of the centerline, while the other one is placed 4 inched to the right of the centerline
- Drain – The drain is positioned on the centerline. The maximum opening for the drain access can be offset by 10 – 14 inches from the framing, and 6 – 8 inches wide.
These dimensions for how high to rough-in the bathroom plumbing should be are not absolute. They should be used as general guidelines, and vary from bathroom to bathroom. For more precise dimensions, refer to the instructions that come with the specific fixture, like sink or tub.
Whether you have a steel frame or wooden frame, it is important that all plumbing pipes be properly secured to the frame to avoid the “water hammer” – situation where water and air rush back and forth through the pipes repeatedly, leading to mechanical damage, like broken pipes, that could result in leaking walls.