Toilet drain flange above the floor and uneven floor

SteamingatMohawk · 11:14AM

Today's dilemma. Tenant contacts me and says there is water on the floor in the basement below her first floor toilet. Upon investigation, when the toilet is flushed, water trickles down along outside of the 4" cast iron elbow and from gaps in the plywood installed on the underside of the floor.

I removed the toilet. The top of the toilet flange stands between 3/4” and 15/16” above the uneven tile floor. On the bottom of the toilet, the space for any fittings (i.e., wax ring, etc.) is only 3/8”. Being a novice at the time, I grouted the toilet into place with the thickness being around 3/8” by measurement after removal. That was done in 1989.

The grout has cracked in places over the years and all I have had to do is patch/caulk it. There was never any indication of the toilet being loose.

The wax ring that was installed had a plastic horn that went from the 4” flange to the 3” OD of the drain on the toilet. When I removed the toilet, the wax ring was black and looks like it may have been squeezed too thin failing over time.

The flange is a simple 4” plastic toilet flange and has a 4” diameter piece of pipe attached. I don’t know if it came as one piece or was a short pipe section glued to the flange. No tapers like what is in the big box stores today.

There are no indications of leakage from the flange to elbow connection, so I am unsure of doing a replacement. Further I do not know how deep the inside socket is in the elbow. If the bottom of the flange already sits at the end of the elbow, replacing it will not reduce the height and is a waste of time. Here are dimensions from the Charlotte Pipe web site. I’m guessing it is a service pipe, not no-hub and the depth is “Y” in the sketch. My most reliable local plumbing supply house is closed today.

I am considering placing a spacer the shape of the toilet footprint to raise the entire toilet and provide additional stiffness, then grouting or caulking any gaps. Additionally, I came across a 4” Fernco flexible fitting (FTS-4) that adheres to the bottom of the toilet and has ridges.

Suggestions?

EBEBRATT-Ed · 4:22PM

I guess unless you want to recipe things raising the toilet is the only option. Many don't realize that the flange is supposed to sit on top of the finished floor.

Your problem is a little unusual as most flanges are too low as flooring gets replaced on top of the existing raising the floor.

I suppose if the flange to pipe connection is good installing a new floor on top of the old floor would help.

Of course you may have time constraints and if there is not a second bathroom that can be an issue.

Maybe one of the newer gaskets that don't use wax is the answer. Never trusted them I always use wax but Fluid Master has some newer stuff. Some are almost like spring loaded and compressible.

Larry Weingarten · 4:25PM

Hi, It seems to me that stabilizing the toilet must come first. I'd be looking at making that support from some plastic wood, like Trex, so rot and cracking are not concerns. I'd also want to know that the bolts holding the toilet down are solid brass with brass or stainless nuts and washers. Also, check the condition of the flange to see if it might have any problem/weakness. Now, the toilet should not be able to move, and whatever seal you use between flange and toilet will hold up better. Is all of that too general? 🤔

Yours, Larry

hot_rod · 5:11PM

how is it thst the floor is uneven? It it a framed floor?

The flange should be on top of the finished floor, could be 1/2” or more above

3/4” above might be a bit much

Toilet drain flange above the floor and uneven floor

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