Height of Toilet Flange and Drain Pipe.

Old 12-10-05, 04:11 PM
Mary Weltzien
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Height of Toilet Flange and Drain Pipe.

I am putting in an addition to an old house. (circa 1920.) It has taken me almost two years, but I am almost finished. I finished with the bedroom, laundry, hallway, and stairs already, but I am having a problem with a detail for the bathroom, which I hope someone can help me with, please? I am having some difficulty finding an answer to what seems to me to be a simple question.

The old house has a 4" cast iron stack. The largest sewer line I could tie into this old system is 3". I already put in all connections to this new 3" ABS branch line, except one. That is the 3" pipe leading from the commode to the rest of this new branch line.

I don't know at what height --in relation to the floor-- to make this pipe, so I can attach the toilet flange. I already put in an eighth inch vinyl floor around the hole I made for the commode. But I have received conflicting advise from several salesman at home supply stores. One says I need to carve away that new vinyl tile so the toilet flange is flush with the floor. Another advises me to just make the 3" ABS flush with the present height of the floor--vinyl included. I am not sure that advise is right either, because the toilet flanges seem to be different dimensions. (Because I get so much strange advise from different people, I am not sure who to trust.)

Can you help me please? I need to know at what height to put the sewer drain for the commode, in relation to the floor of the bathroom. Secondary to that: Is there a need for an eighth inch clearance under the flange?

I am confused. Will you help me please?

Thank You. Mary.
Old 12-10-05, 06:50 PM
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Most PVC closet flanges are 3/8" of an inch thick. This is what needs to be above your finished floor surface.

When you install your flange, whatever finished surface, whether tile, linoleum, or wood should go under the closet flange. This ensures no possibility of height problems with the flange, no matter what brand or type of toilet you install. This is the industry standard found in any home built in new construction. If there is a tile floor to be installed, the plumber is made known well in advance to make sure the flange is above the tile as a finished elevation.

Linoleum is not a big issue with flanges, unless the installer is going to use luan underlayment. If that is the case, then the luan needs to go under the flange, not abut it. Wax rings can be very forgiving but at this stage, doing it a certain way will yield a more common result.

Last edited by DUNBAR PLUMBER; 12-10-05 at 07:00 PM.
Old 12-11-05, 09:08 PM
Mary Weltzien
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Thank you.

I still need help.

Maybe my question is unclear.

The more important question is: At what height do I set the pipe in relation to the floor? (I mean the pipe which the flange will be glued to.)

Does this pipe, the one which the flange will rest on, need to be flush with the floor, or does it need to be at a different height?


Last edited by Mary Weltzien; 12-11-05 at 09:11 PM. Reason: Basic Question Unanswered

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