New construction toilet riser not plumb on slab

Roaddoggie · Feb 11, 2014

I tiled a bathroom (new construction on concrete slab) and am setting the toilet also. I cut off the 4" pvc toilet riser flush with the tile and test fitted the toilet flange, but noticed that it will not sit square to the floor. It's about 1/4" higher on one side due to the riser not being plumb. What's the best way to handle this, short of tearing up the floor?

Terry · Feb 11, 2014

If the toilet sets over the flange, you're fine.
Wax will conform. There is about 3/8" of space under the bowl.
Also, it may be that once you apply the solvent glue, it will slide down farther. Fittings don't normally engage fully unless you have applied the solvent.

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Roaddoggie · Feb 11, 2014

Thanks Terry, I just set the flange in place until it got tight to check plumb and am pretty sure it will be about 1/4" high on one side when glued down. Do you think a SS flange will pull flat with tapcons or do I just leave it high and let the wax take care of it? Also, what work around can you do if the riser is even more out of plumb? Could you use a SS repair flange (with no stub), screw it down and seal the joint to the tile with something?

hj · Feb 12, 2014

You NEVER want to use a plastic flange, only metal ones. If you screw it tight to the floor, but the riser is off plumb, you will probably "pop" the flange out of its recess on the fitting. Dry fit the toilet. If it does not contact the flange there is no problem. The flange MUST be connected to the pipe. If you are going to use a "repair flange screwed to the floor", you might as well not use anything and just screw the toilet to the floor over the pipe, like was done in the early 1900's

Roaddoggie · Feb 12, 2014

Thanks HJ, I always use SS flanges. What I was wondering is why, given as many of these risers get hit during construction, someone doesn't make an toilet flange with a few degrees offset to fix the problem without having to tear out the slab.

Terry · Feb 12, 2014

Roaddoggie said:
Thanks HJ, I always use SS flanges. What I was wondering is why, given as many of these risers get hit during construction, someone doesn't make an toilet flange with a few degrees offset to fix the problem without having to tear out the slab.

Huh?

For the riser to be off that many degrees, the entire layout in the ground would be out of whack.
The plumber needed to put a level on it.
That closet plumbing is connected to pipes in the home. You don't "bend" plastic piping out of level like that, it's glued out of level.

Reach4 · Feb 12, 2014

Check that the highest part of that flange sits lower than the clearance the toilet allows. Then I would put shims under the high parts of the flange before screwing the flange to the floor. That way the shims and floor are taking the vertical compressive stress rather than the pipe. It also insures the flange will be stable to allow the wax to do its job.

Roaddoggie · Feb 12, 2014

Terry said:
Huh?

For the riser to be off that many degrees, the entire layout in the ground would be out of whack.
The plumber needed to put a level on it.
That closet plumbing is connected to pipes in the home. You don't "bend" plastic piping out of level like that, it's glued out of level.

With a riser staked to the ground with tape and a piece of rebar, I have seen them bumped by a skid steer spreading sand, and with the flex of a long lateral the riser will be out of plumb. My mistake was just eyeballing the riser before I tiled the floor...

hj · Feb 12, 2014

quote; flex of a long lateral the riser will be out of plumb.

The riser does NOT "bend" out of alignment. If the "long lateral" twists, it should rebound unless a joint breaks. The entire system has to be "crooked" IF the riser was vertical in the first place. What would you have done if you HAD noticed it was out of plumb? Break out the floor and redo it? You should have tile left over so you can STILL do that.

Terry · Feb 12, 2014

I cut off the 4" pvc toilet riser flush with the tile and test fitted the toilet flange, but noticed that it will not sit square to the floor. It's about 1/4" higher on one side due to the riser not being plumb. What's the best way to handle this, short of tearing up the floor?

If you had a 4" riser, you can cut those flush, and then use an inside flange on it.
If you need to nerf the plastic closet flange to make it fit, that should be fine. I would not take out concrete.

Roaddoggie · Feb 12, 2014

You hit a riser from the opposite side of the lateral and move the lateral up, dirt will fill in beneath it and it isn't going back down, so it's out of plumb. And yeah, I have tile and can bust out the slab, but I would be happy to pay $50 for a offset fitting that would save me a day of hard work.

hj · Feb 13, 2014

quote; , but I would be happy to pay $50 for a offset fitting that would save me a day of hard work. You hit a riser from the opposite side of the lateral and move the lateral up,

Might be more than that to cover the development and production costs to make something that would have a very limited demand. In fact, you might be the only customer they ever sold one to, because everyone else seems to get by without needing one. Htt a riser from that direction and it will have a better possibility of breaking rather than lifting up unless it is very shallow. Hit it from the side and it will only "rotate" if it is shallow and then it should spring back. BUT, the real solution is to get a better driver on the grader, or give him a wheelbarrow and a shovel.

Reach4 · Feb 13, 2014

Suppose a 90 degree ell had been used under the flange (rather than a 91.2 degree ell), and the pipe had a 1/2 inch per foot slope. That gives about 1/4 inch lift on the edge of the flange. The high side would be the opposite way as the horizontal flow.

Roaddoggie · Feb 13, 2014

Terry said:
If you had a 4" riser, you can cut those flush, and then use an inside flange on it.
If you need to nerf the plastic closet flange to make it fit, that should be fine. I would not take out concrete.

How about this: disconnect the 3" PVC from the metal ring. Screw the ring to the concrete, then glue the PVC down into the 4" riser, leaving about 1/2" above the ring. Then cut it flush with the top of the metal ring.

On a slab there would be no need for the PVC to be connected to the ring like would be necessary on a pier and beam.

New construction toilet riser not plumb on slab

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