During a bathroom remodel, maintaining the bathroom's basic footprint is essential to controlling costs and mess, as well as keeping on schedule. But sometimes a bath remodel calls for a change in the layout. Moving the toilet is one of those changes in the bathroom layout that is sometimes necessary.
Moving the toilet is not a change to be taken lightly. But if needed, it can be accomplished with substantial plumbing work and a great deal of peripheral work, such as opening up a floor or ceiling, rerouting pipes and drain flange, and re-installing the toilet and other fixtures. This is normally a job for a construction crew and professional plumber, but some very skilled DIYers can successfully do the work. Taking on the job requires a good understanding of the basic steps, as well as considerable experience with all the skills involved.
How a Toilet Is Moved
Moving a toilet is not so much about moving the actual fixture—in fact, installing a toilet is a simple job that takes less than an hour—as it is about moving the drainage and the water supply plumbing to the new location. Once all of the plumbing is in place, installing the toilet is a relatively easy task.
Moving the Toilet Drain
The below-floor toilet drainage pipes are wide in diameter—usually 3 inches—and difficult to route around or through flooring joists. Other services running underneath floors further complicate matters: water supply pipes, electrical cables, insulation, cross-bracing for the joists, recessed lights, and more.
Also, toilet drainage pipes are gravity-fed, which means that they must drop at a vertical rate of 1/4-inch for every horizontal foot. While usually this can be managed, it can limit the distance of the new toilet location, since the toilet needs to remain close enough to the vent stack or main drain to accommodate the necessary slope.
If possible, then, try to plan your new toilet location so that the new drain can run in the spaces between joists, and try to avoid notching out joists to run the pipes. Do so may require adding structural reinforcement if the alterations are substantial enough to compromise the strength of the floor framing.
Moving the Toilet Water Supply
A second part of the project is less difficult: running a water supply line to the toilet. Toilets need a supply of fresh water to fill the tank after every flush. Because these pipes are smaller, they can more easily be routed through joists or even inside of wall systems. A relocated supply line might even tap into the existing toilet supply line and send it to the new location. Bendable plastic PEX pipes make this job easier for do-it-yourselfers when compared to the older classic method of running copper pipes and sweat-soldering the connections.
About This Project
The project described here does not move the home's main drain/vent system, as this feature is shared by other drainage pipes for other fixtures, and sometimes even by other rooms. In our example, the toilet is moved 5 feet (many bathrooms are 5 feet wide) for a total drainage line vertical drop of 1 1/4 inches. The drainage line and water supply line run in the spaces between parallel joists—not across the joists, which makes for a more complicated installation.
Our example assumes that the existing waste vent stack and toilet drain are made from ABS plastic pipe—which is the most common scenario. If your waste-vent stack is made from a different material—cast iron or PVC plastic are other common possibilities—this may slightly change how to connect the new toilet drain to the stack. For example, you will need to use PVC fittings if you are connecting to a PVC waste vent stack.
Equipment / Tools
- Flathead screwdriver
- Putty knife
- Circular saw
- Reciprocating saw
- Cordless drill
- 6-feet of 3-inch drain pipe, PVC or ABS
- 1/2-inch PEX pipe, 8 feet
- Push-fit or compression ring PEX fittings
- Toilet closet flange
- 3-inch diameter PVC or ABS pipe (5 to 7 feet)
- 3-inch diameter long-sweep 90-degree bend, PVC or ABS
- 3-inch wye drain fitting, PVC or ABS
- 3-inch 90-degree bend, PVC or ABS
- ABS glue
Depending on where your toilet is being moved to, the precise drain fittings needed may vary. Be prepared use additional PVC or ABS fittings as necessary to route the toilet drain to the vent-waste stack. It is critical, however, that the flow into the waste-vent stack use the gradual bends provided by sweeps and wye fittings, not sharp elbows that interfere with smooth drain flow.
Remove the Toilet
Remove the toilet from its current location. If the toilet is to be reused, set it carefully aside to avoid breaking or chipping the porcelain. Otherwise, dispose of the toilet in a responsible manner.
Force a rag into the drainpipe to avoid losing tools and to block sewer gases from rising into the home.
Toilet drainage lines that run through flooring systems can potentially be accessed from either above or below. If you have a loose-lay floating floor, you may wish to remove it and cut out enough sub-floor with the circular saw to access the area underneath. This is especially helpful if the subfloor has begun to rot out or if it needs to be entirely replaced.
Set the circular saw blade set to a depth that is about 1/8 inch greater than the thickness of the subfloor. This minimizes damage to the joists, which can be used as nailing surfaces for the replacement subfloor.
Alternatively, if the room below is open and available and mess is not an issue, you may want to demolish the drywall ceiling for access to the toilet pipes above.
Remove the Toilet Flange
With a screwdriver or drill driver, unscrew the toilet flange from the floor, then remove it from the drain pipe. With cast iron flanges that are sealed to the drainpipe with lead or solder, it is expedient to break up the flange with a hammer. If the toilet flange was solvent-glued in place, you will probably need to cut it away with a reciprocating saw.
Cut the Toilet Bend
With the reciprocating saw, cut away the old toilet bend as close as possible to the waste vent stack. The new toilet drain will splice into this severed bend.
Position New Drain Location
The new toilet drain should have at least 15 inches of space from the center of the drain to all side walls, including the shower and bathtub. This provides enough space to ensure that the installed toilet will clear the walls and other obstacles.
Run the New Drain
Run the new length of drain pipe from the new toilet location to the waste vent stack. At the waste-vent stack, install a new wye fitting where you severed the old drain, then use a long-sweep 90-degree bend to direct the drain pipe to the new toilet location.
Fit all the pipes together with the appropriate fittings glued together with a compatible solvent glue. Make sure the drain line slopes down by a pitch of at least 1/4-inch per horizontal foot toward the stack. Support the pipe to the joists with straps along its length.
Install the Drain Stub-Out
Glue a 90-degree toilet bend onto the end of the new drain pipe, then glue a 6-inch length of pipe into the upward-facing socket, extending up through the floor.
Run the Water Supply Lines
Continue the previous water supply line with a single run of PEX pipe through the joists. There is a variety of ways to connect new PEX tubing to existing copper pipes, but one of the easiest is with push-fit union fittings. Support the PEX pipe as necessary along a joist. At the new toilet location, terminate the PEX water supply line with a fixture shut-off valve exposed through the wall.
Where the pipe emerges through the wall, use a copper stub-out elbow with a flange that nails to a stud. The PEX tubing attaches to one side of the elbow, the fixture shut-off valve to the other.
Fit the Toilet Flange
Replace the subfloor and the finish flooring. Cut off the drain pipe flush with the level of the finish floor, using a reciprocating saw. Install the toilet closet flange on top of the flooring by solvent-gluing it to the drain stub-out and screwing the flange down to the subfloor.
Install the Toilet
Install the toilet on top of the toilet closet flange. Connect the water supply and turn it on. Test the toilet.