Fixture Installation & Rough-In
Installing water closets, sinks, showers, and bathtubs including rough-in dimensions and fixture units.
- State standard rough-in dimensions for water closets, sinks, and bathtubs
- Explain fixture unit ratings and how they affect pipe sizing
- Describe anti-scald protection requirements for showers and bathtubs
- Identify faucet types, aerators, and fixture accessories
Leçon 1
Water Closet Rough-In & Installation
Standard Rough-In Dimensions
The water closet (toilet) is the most common plumbing fixture and has strict rough-in requirements. The standard rough-in measurement is from the finished wall to the centre of the closet flange.
Closet Flange Installation
The closet flange is the critical connection point between the water closet and the drainage system:
- Flange must be set at finished floor level - not above, not below
- Secured to the subfloor with screws or bolts
- Connected to the 75 mm (3") closet bend below
- Wax ring or gasket provides the seal between the bowl and flange
Common Installation Error
If the closet flange is set above the finished floor, the toilet will rock. If set below, the wax ring may not seal properly. The flange must be flush with the finished floor surface.
Water Supply Connection
The water closet supply is typically a 10 mm (3/8") chrome supply tube with a stop valve (angle stop) for isolation. The supply rough-in is usually 150 mm (6") to the left of the centre line and 200 mm (8") above the finished floor.
The standard water closet rough-in is 305 mm (12") from the finished wall to the flange centre. The closet flange must be set at finished floor level. A water closet has a 4 FU rating and requires a minimum 75 mm (3") drain.