How to Add a Toilet to a Sewer Stack in a Basement

Locate a 4-inch round cap set in the concrete basement floor. Beneath the cap lies the toilet flange. Nearby, you will find a 2-inch pipe that extends about 2 feet out of the concrete and a square in the floor that's filled with sand or soil.

Remove the toilet flange cap and insert a long water closet bolt on both sides of the flange. Two small slits accommodate the bolts. Insert at bolt by putting the narrow end into the side of one slit and then pushing it to the other side to lock it in place. Do the same on the other side of the flange.

Fit a wax commode ring on the base of the toilet or over the flange.

Set the toilet by lowering it over the tops of the water closet bolts. The toilet has one hole in the base on both sides to accept a bolt.

Slip a washer and a nut on each bolt and tighten the nuts with a wrench until they’re snug but not overly tight. The washers, nuts and bolts all come in the water closet bolt set.

Install a vanity sink and connect a 2-inch sanitary T-fitting between the sink drain and the 2-inch drain stub that extends out of the floor. When you attach any type of PVC pipes or fittings, apply PVC primer first to prep the areas that fit together and then apply PVC glue as directed by the glue manufacturer.

Add a 2-inch PVC pipe to the top of the sanitary T-fitting, connecting it to the pipe stub between the ceiling joists directly above the pipe. This is the vent for the entire bathroom group, including the toilet.