Hey, I have a 90 degree pipe for a toilet flange sticking out of the
concrete about 1 1/2 inches. So I bought a PVC, cast iron replacement
flange. the one with the compression ring around it. I then cut the
pipe level with the floor, but since it was a 90 degree elbow, it
didn't go straight down,but curved. So then I bought a bunch, maybe 3
different flanges to see if any would go in. One of them went in but
obvious it wasn't tight to the outside of the pipe. Then I went and
bought a 45 and 90 degree pipe to see which one would fit in the
existing 4" pipe the best. Neither did but cutting off the top 1 1/2
inch, it will fit in the pipe with about 3/16 inch space around it.
The question then is: Would it be better to put silicone caulk in the
space to hold the pipe in place or an epoxy? Then the flange can get
PVC glued in to it. I hope the question is clear.

I wonder if a 3" elbow would take less space than a 4" elbow?

You could bust out the concrete around the existing elbow, and transition
the 3" elbow to the 4" pipe under the floor. It might give you that extra
inch or so for the closet flange to fit properly. Then mix up a bag of two
of concrete and patch the floor. You could wrap some foam or something
around the top of the pipe that you could remove after the concrete sets.
This would let you slip a normal flange on the pipe.

It would be a bit more involved, but probably more reliable than trying to
hack a sloppy fit with the current setup.

Of course, I would compare a 3" elbow and 4" elbow at the store to see if
there's any real difference in height before I start busting out concrete.


Good luck!

Anthony Watson
www.watsondiy.com
www.mountainsoftware.com