How to Install Toilet Drain in Concrete Floor

DIY renovations are becoming more and more popular with homeowners tackling jobs that were usually left for professionals. If you need to move or install a toilet on a concrete slab you can save some major money by installing the toilet yourself. You will need some special tools, but with a little work you can take care of this task in an afternoon.

Install the Closet Flange

The first step is to center the flange directly on the stub-up in the slab. Rotate it so that the slots for the toilet bolts are located at the side of the flange. Make the location and set it aside. Using your rotary hammer with a 1/2 in concrete bit dress 1 1/2 inch holes for anchors on your marks. Remove the debris with a shop vac. Install the anchors by unscrewing the bolts and gently tapping them into place with your hammer. Next, coat the sleeve on the flange with spray lubricant. Position it on the ground and align the hub with the stub-in. Push it down. You will need to place some wood across the flange and hit that wood with a hammer to fit it in firmly. Now install anchor bolts and tighten them with a ratchet and socket.

Installing the Toilet

Now that the hard part is one, the rest is a lot easier. Open up all of the parts in the toilet kit and insert a bolt into the slots on the side of the flange. Slide a nylon washer onto the stem. Repeat on both sides and position bolts so they are equidistant from the wall. Press the notched washers down so that the bolts are secure. Place the wax ring on the flange and align it over the hole. With help, lift the toilet and set it over the wax ring and bolts. Adjust the tank so that it is parallel with the wall and then place the plastic washers on the bolts. Add steel washers and screw a crown nut onto each bolt. Sitting on the toilet, rock gently from side to side to seal the ring. Tighten the bolts again, and then fit the protective plastic caps over the bolt tips. Attach the supply line from the shutoff valve on the wall to the toilet tank. Tighten with pliers to make sure you don’t have any leaks.

Take your time and ask for help if you have trouble lifting or tightening anything during this task, and you will have your new toilet installed in no time.

Skip to content