Rough-in for Toilet

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rick15752

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Hello everyone,
I'm hoping for some info about the rough-in dimensions for a toilet. I'm replacing my ABS drain system with no-hub cast iron because of defective ABS. I'm working on the 2nd floor bathrooms and following the path taken by the original plumber. I've replaced a lot of the subfloor due to dryrot. I've encountered a problem with the way one of the 2nd floor toilets was roughed. I was planning on cutting the rough opening for the toilet 12" from the finished wall. But, that means I'll have to tilt a 3" cast iron vertical stack, that serves the 2nd floor drains, slightly out of plumb by 3/4". I've got this 3" stack perfectly plumb and would hate to tilt it just to allow me to put the rough toilet opening precisely on the 12" mark. Unfortunately, my home was not framed and plumbed as well as it should have been.

So, it looks like I'll have the center of the rough toilet opening at 11 1/4" from the finished wall instead of 12". I've checked another toilet downstairs and noticed the back of the tank is approximately 1 1/2" from the finished wall. I'm assuming that the rough opening of the downstairs toilet is 12" from the finished wall.

My question is ... how important is it to have the rough opening exactly 12" from the finished wall? I know I can buy a toilet with a 10" trap and be done with it. But, that would limit my choices of toilets, not to mention a higher cost. Also, some of the toilets with a 10" trap require the shut off to be no less than 5 1/2" from center. This would require some additional plumbing to move the copper from it's current position at 3 1/2" from center.

Anyone have a similar experience?

Thanks.
Rick
 

Leejosepho

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My question is ... how important is it to have the rough opening exactly 12" from the finished wall?

I recently installed a new Mansfield 12" ADA-height toilet on a flange that measures 11-1/4" from the wall and I can still get my fingers between the back of the tank lid and the wall. Also, one plumber has told me the tank is sometimes the only difference between a 12" and a 10" toilet using the same bowl.
 

Nukeman

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Right. It depends on the toilet. Most are designed to have about a 3/4" gap with a 12" rough-in. These would allow you to use a 11.25" rough-in, but the tank will be against the wall. Some toilets (like the TOTO Drake) are designed to have over a 1" spacing at the back, so one of these would fit your application and still give a little gap.

When measuring you rough-in, you are measuring from the drywall surface to the flange bolts, correct? Sometimes, people mistakenly measure from the baseboard.

It sounds like you'll be fine. You'll just have to keep the specs of the toilets that you are looking at to make sure there is enough gap designed to fit your application.
 

hj

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Are you just changing the toilet's arm to cast-iron? If not, then just loosen the clamps on the tee and rotate it to the proper orientation. If you are merely changing the arm, there is no good reason to do that.
 

rick15752

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Hi,
Thanks for the quick replies. I've completely removed all ABS DWV above the 1st floor. Following the original path taken in the rough-in, I used 3" no-hub cast iron up to the 2nd floor bathrooms. That 3" riser 90's under the 2nd floor and that 90 connects to a 3" wye which is position so one leg is over the other. The straight leg (bottom) of the wye continues horizontal to another toilet, a shower and tub. While other leg (top) of the wye serves the toilet in question. That leg connects to a street 45 which connects to a street sanitary tee (vent) which finally connects to a closet bend. There is no clearance between these fittings so there is nothing to rotate to achieve the 12" position.

When I removed the original defective ABS I didn't pay attention to the rough opening in the subfloor on this particular toilet. But, I remember that the tank seemed closer to the wall in this bathroom compared to the other bathrooms. So, I suspect the original plumber had the same problem when the home was built. This is a tract home and it's poorly framed.

Also, my measurement was taken using a piece of 1/2" drywall against the stud wall. I've gutted these bathrooms of the baseboards and drywall. I was hoping to tile the wall behind the toilet with 3/8" ceramic tile. But now I'm rethinking that because of this problem.
 

Jadnashua

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The only way to ensure any toilet will fit is to have a 12" true rough-in. If not, then you need to look carefully at the spec sheet of the toilet you want ot install...it might fit, or it might not. Adding 3/8" of tile and thinset to the wall won't help matters, either! So, choose your toilet, and keep in mind that if you ever do want to remodel and change it, you'll have to look carefully for something that will fit. A true 12" would make it much easier, and maybe more if you decide on tile as your finished surface wall.
 

hj

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I have not the foggiest idea of how those fittings are installed relative to each other. The description makes sense to you because you can see the fittings. We do not have that luxury.
 
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