View Full Version : loose waste pipe/replacing flange questions.

11-03-2008, 06:14 AM
This is a great forum that helped me to redo my half bath about a year ago. Now I am on to my next project and have new questions.
I am retiling a master bathroom floor and when I removed the toilet and old tile I found that that waste pipe for the toilet has at least 6 inches of vertical play. (second floor bath, If you lift on the flange it will raise approx 6 inches)
Also now that I removed the old tile the toilet flange sits about 2 inches above the subfloor.
I have 2 questions:
1) Is the 'play' in the waste pipe ok or do need to somehow make it stationary?
2) I will need to add a second layer of plywood to my subfloor before tiling. how do I remove the old flange and lengthing the waste pipe?

11-03-2008, 08:38 AM
I'd be very interested in seeing how that pipe is supported under the floor...

11-03-2008, 09:18 AM
I won't be able to tell how or if it is supported without cutting out a piece of subfloor. I was hoping to avoid this since there is no damage around the floor where the toilet was. The toilet has been in use for the 13 years we have owned the house with no problems (at least not yet). I did remove some of the subfloor to have the shower drain and water lines moved and the shower drain was just resting on a 2X4 that was connected to 2 floor joists. The drain fro the shower was not 'attached' to the 2x4, it was just resting on it. Is it likely the waste drain for the toilet is the same?
When I look down the waste drain I can see the pipe make an angle turn about 8-10 inches down that I assume must then connect to the waste stack.
Do I need to pull some more of the subfloor?

11-03-2008, 09:27 AM
If you have enough vertical height that would allow you to insert a coupling, you can cut off the existing flange low enough to add a coupling and a short stub, then a new flange to be installed on TOP of the new FINSIHED floor.

You don't want tension on the plastic pipes when installed. I'm wondering how much tension there is if you can raise it 6". None of the connections should have anywhere near that amount of flex unless the arm is VERY long, and with at least 3" diameter stuff, which is stiffer than the smaller stuff, it just doesn't sound right.

The flange needs to be anchored through the tile and into the subflooring - this will hold it in place. With the amount of flopping around you indicate, you might have a real tough time gluing in a new fitting since it takes some pressure to fully seat the socket of the fitting. YOu don't want to push it down to the ceiling below, since you then may have lost all of your slope. I think I'd want to look under there and see what's going on, either by removing some celing below, or some subflooring above.

Gary Swart
11-03-2008, 09:52 AM
It's pretty obvious there is no proper support for the pipe under the floor. It may be resting on the ceiling joists below which would make me concerned about how they achieved the proper slope. I suppose it would have been possible with shims of various heights along the horizontal run, but I concur with Jadnausha that you need to know for sure how it was done before you do the finished floor work. The pipe should not hang on the flange nor should is have sags.

11-03-2008, 10:53 AM
I guess that would make it 3-0 in favor of having a look see...

11-04-2008, 07:15 AM
Looks like I'll cutting some more subfloor out this weekend.
I'll remove the existing flange and add a stub while I am at it. Thanks for the help.

11-04-2008, 07:44 AM
Many times it is less intrusive to go through the ceiling below.

11-08-2008, 07:06 AM
I was able to cut a hole in the sub floor around the waste pipe this morning. The pipe is strapped (metal strap) to a 2X4 that is not attached to the joist. It is long enough that apparently it was resting across 2 joists to support the waste pipe and keep it from resting on the ceiling below. Of course when I cut through the floor I found that one end of the 2x4 was no longer on a joist and was resting on the ceiling below. I also found that the strap was very loose and there was a piece of 1x2 sitting next to the 2x4. I suspect that the 2x4 did not give enough slope so the builder just stacked a 1x2 on top. they were not attached to each other and were sitting lose on the joists.
Looking under the floor the waste pipe runs about 3-4 feet and is attached to a 'wye' that appears to be the drain from the tub and shower.(perhaps even from the 2nd bath which shares a 'wet wall' with the master) The waste then continues for at least another 4 feet or so towards the wall where the sinks are located. This is directly above the utility room with washer/dryer so I suspect that the main stack is there.
I now have a number of questions about fixing this:
1) what is the correct 'slope' for the waste pipe? (from what I see it looks like the slope was supplied from the flange resting on the floor and not from the 2x4)
2) Am I correct in thinking I should attach my waste pipe support (2x4) to the joist so there is no upward play in the pipe?
3) to extend the waste pipe for the new floor and flange do I just use an adapter and add 6 inches or so the the waste pipe?
4) The waste pipe (abs) has a 4" written on the side but when I measured the diameter it looks to be 4.5 inches. Is this a standard size (4 inch?) ?
I apologize for the long post and many questions. What was going to be a simple shower replacement and new floor tile has turned into a total tear out.

11-08-2008, 07:14 AM
I just realized I may have put this thread on the wrong forum, toilets instead of the general plumbing forum.:confused:.

Is there a way for a moderator to move it? Or is it ok here?

11-08-2008, 04:24 PM
Waste pipe is measured by the inside diameter, so 4.5" OD is about right. You want a minimum of 1/4" per foot slope, more is okay. Actually, for 4", you can get by with slightly less, but strive for 1/4". Maybe a more important point is to not have any bellys, or dips in the run. That's why it is important to support pipe, especially plastic.

11-11-2008, 10:22 AM
First off thanks for moving this thread. To determine the 1/4 inch per foot slope, is it valid to set up a 2 foot board (assuming I find a straight one) with a 1/2 inch spacer on one end and then put a level on it. If I then note where the bubble is on the level and then put the level on my waste pipe and set it so the 'bubble' is in the same place on the level do I have my 1/4 inch per foot slope?
Once I have the slope established I plan to place a support under the waste pipe and attach (screw) the support to the joist. I think this will keep the correct slope. I then plan to strap the pipe to the support to prevent upward movement as well. Is this a good approach to get and hold the correct slope?

11-11-2008, 11:51 AM
That should work...

11-11-2008, 12:44 PM
To get the proper slope you angle the pipe with the level just breaking the bubble on slope

11-17-2008, 11:54 AM
I just wanted to thank all who responded to my questions. This past weekend I attached the waste pipe to the joists and strapped it down as well. The pipe now has the correct slope and is no longer 'loose'. Now I move on to adding underlayment to get ready for tile. Thanks again.

11-17-2008, 03:38 PM
Good job! You did the right thing.:D