How to Install a Floor Drain for the Laundry Room

Water is in abundance in any laundry room, so taming it and sending it in the right direction is critical. Since that water has nowhere to go, move it in the right direction: down a drainpipe and into the sewer main. A laundry room floor drain is the escape route for the water. Much as your shower drain collects water at a central point and sends it down and away, so too can a laundry room with a drain installed at the lowest point in the floor.

How Does a Laundry Room Floor Drain Work?

A drain in a laundry room provides a route out of the room for spilled water. Water on the laundry room floor moves to a 2-inch drain covered by a grate. The water flows vertically down a short initial section of ABS pipe below the floor, then through a P-trap, and out to the sewer main via branch drain lines within the house.

Flooring Considerations

Most floors expect only minimal amounts of water. A laundry room with a drain behaves more like a waterproof basin.

Installing the laundry room floor drain ideally should be done as part of a flooring new-construction or full remodeling project. One reason is to provide full access to the structure below the flooring to run the pipes. Whether or not you build a new flooring system, the waste and vent runs will need to either run between the joists or the joists must be drilled to allow pipes to run perpendicular to them.

A completely waterproof floor sloped down to the drain must be built. Much like a shower pan, a sheet or liquid waterproof membrane should be placed under the floor covering (such as tile). The membrane should extend several inches up the walls and should be flashed to the drain collar, extending at least 24 inches from the collar.

Drain Placement

If your laundry room floor slopes to a central point, that is the logical place to place the drain. If the floor is flat and level, you may choose to locate the drain in a certain spot with the expectation that later on, you will create a sloped floor.

You should also think about the area underneath the laundry room. Do you have easy access or do you need to create access? Most importantly, is there an existing drain pipe that you can tie your laundry room floor drain into?

Codes, Permits, and Regulations

Drain line work typically requires a plumbing permit. You will need to apply for a plumbing permit with your local permitting office.

Safety Considerations

Before cutting into the ceiling below, shut off all power to that area via the circuit breaker. Also, turn off the water at the main shutoff valve or an intermediary in-line valve.

Before You Begin

Before you begin this project, locate the eventual tie-in point where you intend to locate the sanitary tee. A sanitary tee is a plumbing fitting that connects a branch line (like the laundry room's drain) to the vertical drain that leads out of the house.

If the lower area is a habitable floor or a finished basement, you may need to remove a portion of its ceiling. Drop ceilings on suspended metal grids can be accessed by removing ceiling panels. If you have a drywall ceiling, you must cut into it, remove the relevant portion, and then re-install drywall after you have finished.