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alqugrub 01-15-2010 08:29 AM

Uneven toilet flange
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Rough in plumbing had been done in the basement when the house was built. I am now getting around to putting in a basement bathroom. The toilet flange had been installed in the concrete floor and was flush with the concrete surface. It was also not level (half inch drop from one side to the other), and the bolt holes were not aligned correctly for the toilet to sit at a right angle to the wall.

I decided that the simplest thing to do would be to remove the flange from the drain pipe and install a new one at the correct height, for the new floor, and orientated correctly and then hopefully to correct the level problem with shims for the toilet.

Having removed the concrete I find that I have very little room to play with as there is only 1" of pipe exposed below the flange collar. Also I notice that the installer has connected ABS fixtures to a PVC pipe. I have to presume that they used the correct cement for this.

What I need advice on is which of my options is likely the best.

option 1: cut off the flange just below the collar and use a coupling to attached a new short ABS pipe section and new flange. Raises the height of the flange and allows me to correct the flange orientation, but does nothing to help with the level problem.

option 2: cut off the ABS pipe where it joins the PVC pipe and install a new ABS elbow and flange, would allow me to correct height, orientation and level, but there is only a short section of the PVC pipe (3/4") available for the connection. This short piece of PVC pipe then enters an elbow, exposing which would require removing a much larger chunk of the concrete floor (rather not do that).

option 3: use a flexible coupling after cutting off the flange, to connect a new flange to the 1" section that would remain.

I would really appreciate comments as to the best course to follow. I should also point out that PVC toilet flanges are not readily available here in Canada (or at least at any of my local hardware stores).

RegeSullivan 01-15-2010 10:09 AM

Find a way to get the ABS out of there and connect properly to the PVC. If you have to you can cut the PVC pipe flush with the PVC fitting and use a PVC/ABS fitting reamer ( to clean out the fitting hub. You might need a good angle drill to get a good cut with the position of the fitting. First I would find out what is beyond that fitting. If it is pipe and you can cut it back far enough you can easily make the new connection.

One other thought... Try twisting that ABS fitting off... You never know, because there is no glue that works when putting ABS and PVC together it just might come apart. They do make combo glues but they are intended to glue PVC to PVC and ABS to ABS but not PVC to ABS.


meboatermike 01-15-2010 04:37 PM

I know you do not want to but it does not look like it would take to much to pound/remove some extra concrete from that area if need be. I know (cause I have done it) here in the US, Home Depot rents good sized electric jack hammers that would make short work of that. :thumbup:

plummen 01-17-2010 06:00 PM

go just past the coupling and replace it with pvc up to floor vevel and be done with it

fulcrum 01-25-2010 08:05 PM

I agree with Rege.
ABS and PVC are not compatible and no glue to correctly cement together.
twist the flange and it'll come off.

HandyPlumber 08-27-2012 07:52 PM

There are 'glues' that work for PVC and ABS applications - they are called transitional solvents. And - yes they do work... And they work very well.

Looks like for whatever reason the plumber used a PVC coupling and a short nipple before transitioning to ABS. May have changed plans during the rough in - who knows. If you can cut the pipe downstream of this coupling - do so and dig out a little more gravel and fill around the pipe that's left. From there Bob is your uncle.

make sure the pipe is clean using rags etc - then use an approved PVC cleaner as well - it's usually purple and the smell will knock your socks off. Then use whatever materials you want - PVC or ABS to complete the piping. Keep in mind the PVC that is used there may not be Schedule 40 it may only be sched 20 - this may be why the plumber used ABS to complete the job. If this is the case some special cheater sleeves will be needed to 'bush' a coupling. They look like a really thin coupling.

If this piping is 3" - I would suggest using a 4x3" 90 degree elbow to go from vertical to horizontal.. this way you go 3" into the bottom (horizontal) part of the 90, the 4" out of the top. Use a short (18" or so) length of 4" pipe for the vertical part out of the 90. I would put the 4" part in first to ensure it was fully engaged and straight - then after affix the whole thing to the 3". use your level and do your best to make sure the 4" pipe is straight vertically and hold it until that glue is good and set.

Refill and pack the soil - gravel etc. and pour your concrete. This way you can finish your concrete around the pipe and don't have to worry about the height of the glues in flange at this time.

A flush fitting floor flange (not adjustable) meant to go out side of 3" pipe will fit perfectly on the inside of 4" pipe. So what you do is cut the 4" pipe off flush with the floor and the line up your flange for the correct bolt orientation at 12" from finished wall and glue that sucker in. I always drill holes and use concrete around the flange as well for extra support.

The other option since it is a basement is to use a brass floor flange. Cut the pipe as mentioned above and then pin in or screw down the brass flange.

Hope it works out for you!

TheEplumber 08-27-2012 08:16 PM

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How do you find these 2 year old threads? :drink:

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