A toilet gasket, or “closet flange,” sits between the sewer inlet in the bathroom floor and the toilet bowl. The rubber gasket acts as a watertight seal and prevents water from leaking out of your toilet every time it is flushed, as well as providing an airtight seal to prevent sewer gases from leaking out from the sewer and into your house. Most gaskets are made out of wax, which, although cheaper, tends to degrade over time. A rubber gasket will last much longer and is not much more expensive than a wax ring.
Step 1 – Clean off the flange area. Scrape up any remnants of old wax rings with a putty knife. Use a household cleaner and rags to wipe up any gummy residue. Insert the flange bolts, with the threads facing upward, into the flange.
Step 2 – Turn the toilet bowl over so that the sewer outlet on the bottom of the bowl is facing up. Insert the tube of silicone caulk into the caulk gun. Trim off the end to the 1/4-inch mark. Apply a bead of caulk around the perimeter of the sewer outlet.
Step 3 – Press the rubber gasket in place around the sewer outlet. Hold it there for a minute or so to allow the caulk to set and hold the ring in place. Apply another bead of caulk to the surface of the rubber gasket.
Step 4 – Turn the bowl over (being careful not to knock the ring out of place) and maneuver it in place over the flange. This part is tricky, especially if the bowl is heavy. Have an assistant help you, if possible. You have to set the toilet over the flange so that the sewer outlet on the bowl lines up with the inlet on the flange, while at the same time making sure that the flange bolts poke up through the holes at the base of the toilet.
Step 5 – Slip the rubber and plastic washers over the flange bolts once the toilet is in place. Screw on the flange nuts on the flange bolts. Tighten the nuts by hand at first. Tighten one side with one turn of the wrench, then do the other. Repeat this process until the toilet is firmly seated against the floor.