How To Install a Toilet Flange Extender

install a toilet flange extender
© Elizabeth Weintraub

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 up to 1/4 inch above 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 technically a code violation, so it's important to remedy the problem by installing a flange extender.

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 simply 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 plastic spacer rings of a few different thicknesses to accommodate different flange heights. Most extenders are fastened to the subfloor (through the holes in the old flange) to secure them.

To create a watertight seal, extenders either include a rubber gasket or they should be sealed with caulk when installed.

Installing a Flange Extender

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 works before you gather the rest of your supplies and learn how to install it.

Installation steps vary, of course, but here is the basic process:

  1. 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 reside with mineral spirits.
  2. 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.
  3. Remove any screws securing the old flange to the subfloor. You will likely use some or all of the screw holes for securing the flange extender.
  4. Apply a liberal amount of silicone caulk on 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.
  5. Set the flange extender into place over the old flange, including any spacers, as applicable. Align the screw holes in the extender with the open holes in the old flange.
  6. Fasten the extender to the subfloor with the provided screws.

When it's time to install the toilet, fit two new closet bolts (toilet-to-floor bolts) into the bolt slots on the extender. Set the toilet, using a deep-seal wax ring fitted to the horn of the toilet.