How to Connect a Commode to a Concrete Floor

Commodes are a fundamental part of any bathroom and install on a variety of subfloor materials, including plywood and concrete. Connecting a commode to the waste pipe in a concrete floor is identical to attaching it to a plywood subfloor. The main difference is installers use a different type of screw to attach the main floor flange. Instead of wood screws, special concrete screws are required to penetrate and grip the harder subfloor surface.

Commode flange
Tape measure
Pencil
Hand saw
PVC cement
1/4-inch masonry bit
Drill
Self-tapping concrete screws
Wax ring
Commode floor bolts
Nuts
Washers
Wrench
Hacksaw (optional)

Instructions

- 1
  Turn off the water supply to the commode, if not already accomplished, by turning the rear wall knob counterclockwise.
- 2
  Examine the floor pipe to determine if a cap is in top of it, which is often the case in unused pipes. If a cap is in place, remove it using a wrench and stuff a rag inside the opening.
- 3
  Insert a commode flange in the top of the waste pipe and measure the distance between the bottom of the flange and the top of the floor. Remove the flange and measure the same distance using the tape measure, marking it with a pencil. Cut off the pipe using a hand saw. If the pipe is already flush with the floor, skip this step.
- 4
  Turn the flange upside down and apply PVC cement around the outside of the rim. Remove the rag and apply another layer of PVC cement around the inside of the waste pipe. Push the flange into the top of the pipe until it is flush with the floor.
- 5
  Insert a 1/4-inch masonry drill bit into a drill and create 1-inch-deep holes in each of the screw hole locations of the flange.
- 6
  Insert self-tapping concrete screws into the screw holes using a power drill. Then turn the two long closet bolts with the heads facing downward. Slide a bolt head into each of the round or oval holes in the flange and slide them under the slit to hold them in place. Screw a nut on top of each bolt.
- 7
  Open a new wax ring and press it over the center of the flange, aligning the holes perfectly. Wax rings come in 3- and 4-inch-diameter sizes, so measure the bottom opening of the commode to ensure a snug fit.
- 8
  Pick up the commode and set the two base holes over the bolts. Push down on it firmly and rock it to settle it into the wax.
- 9
  Insert a washer and a nut over each bolt head at the base of the commode. Tighten each nut using a wrench and screw plastic bolt caps over each bolt.
- 10
  Grasp the water hose from the rear wall shut off and connect the end to the back of the commode. The end of the hose has a nut that simply screws onto the inlet valve on the commode. Tighten the connection with a wrench to prevent water leaks.
- 11
  Turn the water supply on by turning the rear wall knob clockwise.

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Plumbing