I recently purchased an old farm house. During our work to renovate and upgrade we have had to replace the entire bathroom floor(rotted joists, broken joists). Anyway, I have a toilet I am ready to install but the floor is higher than the old rotted floor. I bought a flange extender but the hole in the floor is too large. Can I secure the old flange from underneath and then mount the flange extender and the toilet to the old flange?
I am trying to prevent having to remove subfloor I have already put down. I didn't have the forsight to see that the old flange and pipe would end up lower than the new floor.

"the hole in the floor is too large" you made your new floor hole too large, is that what you are saying. What material is the drain pipe, cast or PVC? With the flange spacer in place you are OK if the top surface of the spacer is within 1/4" of the floor surface. Beyond that you can add another spacer but we will need to shun you at the next plumbers ball. An oversized wax ring should also be used. By the way, is the old flange still properly secured to the old sub floor?

Chuck... if I read this right... only trick I know of for this is to cut a 3/4" piece of plywood slightly smaller than the width of the joist bay downstairs x 12inches long. Then I use a jigsaw and cut a hole in the plywood big enough for pipe to pass through. Then I cut down the middle of the plywood so I have two halves of plywood. Then I install the plywood up tight to the pipe and SCREW the plywood up tight to the underside of the subfloor.

Now, go upstairs and see if you can screw the old flange and the extender kit together through to the new plywood downstairs. Then install wax gasket and johhni bolts and install the toilet. All this should result in a strong/stable installation.

Let me know what you think. Mark

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"the hole in the floor is too large" you made your new floor hole too large, is that what you are saying. What material is the drain pipe, cast or PVC? With the flange spacer in place you are OK if the top surface of the spacer is within 1/4" of the floor surface. Beyond that you can add another spacer but we will need to shun you at the next plumbers ball. An oversized wax ring should also be used. By the way, is the old flange stil properly secured to the old sub floor?

Drain pipe is cast, and has never been secured to anything-another problem...

Chuck...if I read this right...only trick I know of for this is to cut a 3/4" piece of plywood slightly smaller than the width of the joist bay downstairs x 12inches long. Then I use a jigsaw and cut a hole in the plywood big enough for pipe to pass through. Then I cut down the middle of the plywood so I have two halves of plywood. Then I install the plywood up tight to the pipe and SCREW the plywood up tight to the underside of the subfloor.

Now, go upstairs and see if you can screw the old flange and the extender kit together through to the new plywood downstairs. Then install wax gasket and johhni bolts and install the toilet. All this should result in a strong/stable installation.

Let me know what you think. Mark

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This is actually a better version of what I thought of a little while ago-probably how I will finish this project-thanks. With the original flange not being secured to the subfloor, I think I know how the floor ended up rotted under the toilet... thanks again

"the hole in the floor is too large" you made your new floor hole too large, is that what you are saying. What material is the drain pipe, cast or PVC? With the flange spacer in place you are OK if the top surface of the spacer is within 1/4" of the floor surface. Beyond that you can add another spacer but we will need to shun you at the next plumbers ball. An oversized wax ring should also be used. By the way, is the old flange stil properly secured to the old sub floor?


Long story short-I sistered 8 of 9 floor joists because of damage to them in the toilet area-this was to level the floor, never thought about the level of the flange during this process-of course it became very evident when I started laying new subfloor that the flange was going to be beneath the new floor-I started investigating options and ended up here hoping to find some answers... thanks

Chuck... glad you like.

If you want to be real thorough... fill the void between the flange and the plywood (upstairs) with hydraulic cement (available at all home suppliers... expands slightly). Then set flange and extender, THICK wax ring if needed (as Ballenger suggested), etc. The screws really bite in and secure all this real strong. Good luck with it.. let us know how it goes.