Every toilet I've ever worked with (not many, I admit) has a stack in the wall directly behind it, including mine. I'm re-doing my bathroom and I'd like to install a wall-hung toilet. I have 2x4 construction, and Toto makes an in-wall tank designed to fit between 2x4s. Great. However, the diagram they give indicates my stack would by right in the way of the tank, and their document doesn't contain the terms "venting" or "stack" anywhere. Here is their installation guide (PDF)

enter image description here

What do I need to do to make this work?

  • Good question. That manual seems to just show the soil pipe going straight down, right underneath the tank, with no vent. Maybe it's worth a call to the manufacturer? I assume you'll have to follow @MichaelKara's advice and move the toilet or the stack (if it's really there). Maybe that style of toilet is really intended for new installation.
    – Hank
    Oct 31, 2013 at 4:02

2 Answers 2


The simple answer to your dilemma is that you have two choices..either relocate the toilet location to one side of the vent stack - or - to route the vent stack pipe around the place the 'in-wall' components are mounted.

On top of that if your stud spacing is not now 25-3/8" you may be doing some framing work in your wall anyway.

  • You are correct, of course. Unfortunately, it is impossible to move a 3" stack across 2x4 studs. I did notice that the tub is sharing the same drain/vent system as the toilet, so I think if I took its drain and vented that (it's only 2"), the whole system would be vented and it would work. Still, it's looking like this might not be the best idea and I might have to revert to a normal toilet. Nov 2, 2013 at 2:18

Don’t call Toto. Call Geberit, part of Chicago faucets. They have much better tech support for diy’ers. Wall toilets vent the same as any toilet. One of the advantages of the 2x6 carriers over the 2x4 carriers is that you can alter the angle of the discharge ell. There are also offset discharge Ells available which maybe helpful. Perhaps a prewall installation of 2x6 carrier would allow more flexibility to helping handle the stack you have to negotiate.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.