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 it is needed, it can be accomplished with substantial plumbing work and a great deal of peripheral work such as opening up a floor or ceiling and re-installing them.
How a Toilet Is Moved
Moving a toilet is not so much about moving the actual stool—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 fast, easy task.
Moving the Toilet Drainage
The below-floor toilet drainage pipes are wide in diameter—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.
Moving the Toilet Water Supply
A second part of the project is less difficult: running a water supply to the toilet. Toilets need a supply of fresh water from 1/2-inch pipes 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 than professional plumbers' method of sweating copper pipes. Also, because water supply pipes are pressurized, there are no drainage issues.
About This Project
This project does not move the home's main drain/vent system, as this is shared by other drainage systems: bathing, other bathrooms, and kitchen. 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 are run between joists.
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 long-sweep 90-degree bend, ABS
- 3-inch wye drain fitting, ABS
- 3-inch 90-degree bend, ABS
- ABS glue
Remove the Toilet
Remove the toilet from its current location. If the toilet is to be reused, set it carefully aside and 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.
Toilet drainage lines that run through flooring systems have the potential for either access from above or from 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 of 1/8-inch more than the thickness of the subfloor. This preserves the joints, 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.
Remove the Toilet Flange
With a screwdriver, 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.
Cut the Toilet Bend
With the reciprocating saw, cut away the old toilet bend as close as possible to the waste vent stack.
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.
Run the New Drain
Run the new length of drain pipe from the new toilet location to the waste vent stack. Use a straight length of pipe, running it into the long-sweep 90-degree bend.
The bend should attach to the waste vent stack with a new wye. Fit all ABS materials together with approved ABS glue. The drain line should slope 1/4-inch or more per horizontal foot toward the stack. Support the pipe with straps along its length.
Continue the Toilet Drain
Glue the 90-degree ABS bend onto the end of the drain, then insert a 6-inch length of ABS pipe at the top.
Run the Water Supply Lines
Continue the previous water supply line with a single run of PEX pipe through the joists. Support as necessary along a joist. At the new toilet location, bring up the water supply through the wall and finish off with a turn valve exposed through the wall.
Fit the Toilet Closet Flange
Replace the subfloor and the finish flooring. Cut off the drain pipe flush with the level of the finish floor. Install the toilet closet flange on top of the flooring by screwing it in place.
Install the Toilet
Install the toilet on top of the toilet closet flange. Connect the water supply and turn it on. Test the toilet.