How to Rough-In for Installing a Toilet
When you rough-in a toilet, you install the waste pipes, the vents, the toilet flange and the pipes for the water supply -- in short, everything but the toilet itself. The waste pipes must tie into a vertical pipe, called the soil stack, that connects to the sewer. The toilet can't be farther than 10 feet from the stack, so you'll have to install one if there isn't one within reach. It's also important to remember that you need to install vent pipes above the toilet as well as waste pipes below it. Does this Spark an idea?
Things You'll Need
- Tape measure
- Reciprocating saw
- 3- or 4-inch ABS waste pipe
- ABS waste fittings
- ABS cement
- Hacksaw
- Toilet flange
- Closet bend
- 1/2-inch copper pipe
- Copper fittings
- Soldering supplies
- Angle stop
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Instructions
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Connecting the Waste Line
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1
Mark the position of the waste opening on the subfloor. Its position from the rear wall depends on the toilet model, but in most cases, it's 12 inches. The toilet installation instructions should specify the correct distance, as well as the distance from the side walls.
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2
Cut a hole centered on the mark with a reciprocating saw. If you're using 3-inch waste pipes, the hole should be slightly larger than 3 inches so the pipe will fit through easily without binding. Similarly, if you're using 4-inch lines, the hole should be slightly larger than 4 inches. One of the main determinants of the proper pipe size is the distance between the hole and the waste stack.
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3
Measure the horizontal distance between the center of the hole and the existing soil stack if there is one. If it's 7 feet or less, you can use 3-inch waste pipe; if it's between 7 and 10 feet, you should use 4-inch pipes. If it's more than 10 feet, you need a new stack.
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4
Install a new soil stack, if necessary, by running 4-inch ABS pipe vertically from behind the toilet to a point in the basement where you can extend a 4-inch line with a 1/4-inch per foot slope to the sewer. Glue a long sweep elbow onto the bottom of the stack and extend the line to the sewer. Cut into the sewer with a hacksaw and install a sanitary tee so you can connect the new waste line to it.
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5
Insert the plastic pipe on the end of a toilet flange through the hole you cut in the subfloor and glue a closet bend, which is a plastic waste fitting with a 90-degree sweep, to the end. Screw or bolt the flange to the subfloor so that the bend points toward the waste stack. Measure the distance between the outlet and the stack.
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6
Calculate the point where the waste line meets the stack. It should be far enough below the opening of the bend so the waste pipe has a slope of between 1/8- and 1/4-inch per foot. Cut the stack at that point and glue on a sanitary tee with the sweep on the tee going down. Connect the tee to the closet bend by gluing in the ends of an appropriate length of 3- or 4-inch ABS pipe.
Venting
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7
Extend the soil stack a foot or so above the point where the toilet waste line ties in and glue on an adapter to reduce the pipe size to 2 inches. If you tied into an existing soil stack, you can omit this step because the stack is already vented.
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8
Run 2-inch ABS pipe from the top of the stack vertically through the roof or tie into an existing vent stack, as long as the path between the new stack and the existing one is on an upward slope.
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9
Cut into the waste line that extends from the toilet to the soil stack at a point a few feet past the closet bend and install a tee with the outlet pointing upward. Connect the tee to the stack vent with 2-inch pipe and whatever fittings are necessary to route the pipe.
Water Supply
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10
Turn off the main water supply and cut into an existing water line with the hacksaw at a convenient location. Solder on a tee and run 1/2-inch copper pipe from the tee to the wall behind the toilet. Use whatever fittings are necessary to route the pipe and solder the connections. Stub the pipe about an inch through the wall onto the side of the toilet that has the water connection.
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11
Connect an angle stop, or shut-off valve, to the water supply pipe, either by soldering it on or, if it has a compression fitting, by tightening it with a wrench.
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12
Close the angle stop after you have made all of the connections and turn on the main water supply. Check for any leaks.
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Tips & Warnings
The actual configuration of the waste and vent pipes depends on many factors, including the house layout, obstructions in the walls and whether or not you are connecting any other drains, such as for a sink or shower, to the pipes.
In some cases, it may make more sense to connect a straight coupling to the toilet flange instead of a bend and extend the pipe from the toilet to a waste line located some distance below it.
The plumbing code has strict requirements for toilet rough-ins, and you usually need a permit. If you are doing the work yourself, have it inspected by a licensed plumber to make sure your toilet will work properly and be sanitary.
References
- Photo Credit Brand X Pictures/Brand X Pictures/Getty Images
