How To Replace A Cast Iron Toilet Flange


If you have a toilet in an older home, it is  likely connects by a cast iron flange. Cast iron can become brittle over the years causing the toilet to rock. It is possible to replace the cast iron flange yourself and make the toilet steady to keep it falling through the floor. Replace the cast iron toilet flange by following these steps.

Prepare to Replace Cast Iron Flange

To replace the flange, gather:

  • work gloves 
  • heavy blankets 
  • towels
  • newspapers 
  • pry bar
  • adjustable wrench
  • claw hammer
  • cold chisel
  • hacksaw
  • wood blocks
  • replacement flange

Locate the water supply shut-off valve, which is commonly beside or behind the toilet, and rotate the valve to the right to shut off water. Flush the toilet to remove remaining water.

Remove the Toilet

Spread newspapers or heavy blankets on the floor in safe place to set the toilet. Look for two bolts on each side of the toilet that hold it, and use the wrench to loosen them.

If the bolt are hard to remove cut them with a hacksaw. Remove tank bolts to make the toilet lighter, detach the flexible water supply line, and move the bowl gently back and forth to break the seal. Lay the tank and bowl on the blanket or newspapers.

Replace the Old Cast Iron Flange

Stuff the toilet drain and waste pipe opening with a towel to keep gases out of the room. Cast iron flanges are commonly connected by bolts. 

Use the wrench to loosen the flange bolts, then check the flange with the pry bar to see if it comes loose. Since the stem may be broken, you can lift it from the floor. 

Otherwise, insert the tip of the chisel into the flat part of the flange that rests on the floor. Tap the chisel with the hammer until it breaks, holding the chisel away from the outer flange edge to avoid damaging the waste pipe.  

Loosen the flange by sliding the pry bar under the edge, and pressing up on it all the way around. Insert a small wood shim under the flange, if it doesn't loosen all the way. Contact your waste department for proper disposal of metal.

Place wood blocks around the opening, so the flange will be the correct height. Lay the new flange in place, and chisel the floor until the flange sits flat. Install the bolts, using the wrench to tighten them a little at a time, so you won't damage the drain pipe. Use the hacksaw to trim bolt length, if needed, then screw a plastic washer, a stainless steel washer, nuts, and plastic caps on the bolts.

Install the compression ring, and push the brass ring on top, taping it in place with the hammer. Remove towels from the drain pipe, and reinstall the toilet.

For professional help, get in touch with a full service plumbing company.


16 April 2018

Exploring The Importance of Plumbing Pipes

Hi everyone, my name is Linda Strickerts. I am going to talk about plumbing pipes problems, repairs and upgrades on this site. Although the pipes hide beneath the floors and behind the walls, they are an integral part of the home. Without plumbing pipes, we would still be heading out to the outhouse to do our business. Washing clothes, dishes and ourselves would also not be possible without carrying buckets of water in and out of the home. I hope to explore the different ways plumbing pipes changed our lives for the better. I will talk about keeping the pipes in great shape as well. Thanks.