What Is a Closet Flange?


A closet flange is a plumbing pipe fitting that connects a toilet to its drain line. The closet flange also provides an anchorage for holding the toilet in place on the bathroom floor. The fitting is called a closet flange after an old euphemism for toilets: the “water closet.” Closet flanges are relatively inexpensive. Most types are priced under $15 as of April 2011.

Closet Flange Components

  • The closet flange fitting consists of a flat ring (the flange) with holes for the screws that fasten the flange fitting to the floor and for the bolts that will fasten the toilet to the closet flange. The flange is connected to a hub that fits into the drain line. Three basic types of closet flanges are used. One is made of solid ABS or PVC plastic. Another is made up of a plastic hub with a steel flange. These types are for use with PVC plastic drain plumbing. The third type is made of solid cast iron for use with cast iron drain plumbing.


  • The toilet and the closet flange are two parts of the connection between the toilet and drain line. An essential third part is the sealant that makes the flange-toilet connection watertight. Most installations use a ring-shaped gasket made of petroleum-based wax with added thickeners and stabilizers. This ring is placed on the closet flange, and the toilet is lowered onto it. As the wax is compressed by the weight of the toilet, it conforms to the surfaces of the toilet’s drain outlet and the closet flange to form the watertight seal. The connection between the closet flange and the drain pipe is sealed with plastic cement in the case of plastic plumbing or with solder in the case of cast iron plumbing.

Flange Fixes

  • Bathroom remodeling jobs may reveal problems with existing closet flanges, but plumbing supply houses carry a variety of products for dealing with closet flange problems. For instance, a new toilet may require more wall clearance than the old one, or the drain may have been located incorrectly. Offset flanges can shift the drain hole by anywhere from 1 inch to more than 4 inches. If the old flange is below the level of the new bathroom floor, a spacer ring can build up the old flange, raising it to the correct height. Or maybe you found the old flange had corroded to the point that the toilet bolts had no anchorage. A spanner flange is used for repair if only one side is corroded; but if both sides are badly corroded, a flange repair ring can provide new anchorage for the toilet bolts.

Specialty Flange

  • Flange makers offer specialty flanges for unusual situations. For instance, stainless steel flanges cope with unusually corrosive conditions. Special flange designs are available for installation on concrete floors. Compression flanges replace broken cast iron flanges. They fit inside the drain pipe, and screws tighten a compression gasket to seal the flange to the drain pipe. Brass flanges are used when an old house still has its original lead drain pipes.

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