In a typical toilet installation, the floor flange that sits inside the drain opening below the toilet should be flush with the finished floor, or no more than 1/4 inch above or below the floor. This ensures that the flange makes a watertight seal against the wax ring applied to the horn on the underside of the toilet. But if you add new flooring, or if the flange wasn't installed properly to begin with, the flange may sit too far below the flooring level. Left this way, the toilet may not seal tightly against the drain, creating the potential for leaks around the base of the toilet. This is not only messy but is technically a code violation, so it's important to remedy the problem by installing a flange extender. If you've ever used a toilet that rocks slightly when you use it, the reason may be an improperly installed toilet flange.
How a Flange Extender Works
A flange extender fits over the existing flange to raise the drain connection in relation to the surrounding flooring. (Plastic flanges typically can't be removed because they're glued to the drain pipe.) Some flange extenders are plastic rings that come in various thicknesses. Others are very similar to a standard floor flange but have a slightly smaller pipe stub that fits inside the opening of the existing flange. Some include a special flange and several plastic spacer rings of different thicknesses to accommodate different flange heights.
Most extenders are secured by fastening them to the subfloor with screws driven through the holes in the old flange. To create a watertight seal, extenders either include a rubber gasket, or they will require sealing with caulk when they are installed.
The first step to installing a flange extender is finding an extender that fits your situation. There are many different brands and types, and you want to be sure the product fits your situation before you gather the rest of your supplies and learn how to install it. Installation steps vary, of course, but this is the basic process.
Remove the Toilet
To access the toilet flange, remove the toilet from the drain and set it aside. This is done by removing the nuts holding the toilet onto the tank bolts, then carefully prying the toilet away from the flange. You may want to first remove the tank from the toilet bowl to make this easier. Be careful when removing or moving a toilet; the porcelain is fragile and can crack.
Clean the Flange
Clean the top of the old flange to ensure that the flange extension can sit neatly in place. If there is old wax on the flange, scrape it off with a putty knife, then remove the residue with mineral spirits.
Test Fit the Flange Extender
Check the fit of the flange extender, using one or more spacers, if included with the extender. The top of the flange extender should be flush with the finished floor or no more than 1/4 inch below or above the floor surface.
Install the Flange Extender
Remove any screws securing the old flange to the subfloor. You will likely use some or all of these screw holes for securing the flange extender.
Apply a liberal amount of silicone caulk along the bottom lip of the flange extender. Alternatively, if the flange extender comes with a rubber gasket, apply the gasket as directed by the manufacturer. Set the flange extender into place over the old flange, including any spacers, as needed.
Align the screw holes in the extender with the open holes in the old flange. Fasten the extender to the subfloor with the provided screws.
Reinstall the Toilet
With flange extender in place, you can now replace the toilet. It is generally best to use a new wax ring when reinstalling the toilet. When using an extender, set the toilet using a deep-seal wax ring fitted to the horn of the toilet. When the toilet is in place, run a bead of silicone caulk along the seam between the base of the toilet and the floor.
Your toilet is now securely in place and fits perfectly against the floor surface.