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Thread: What Does Rough-In REALLY Mean?

  1. #1
    DIY Junior Member jbell94521's Avatar
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    Default What Does Rough-In REALLY Mean?

    I'm confused. I understand that a 12" rough -in toilet means that is it intended to be installed with the flange bolts being 12" from the surface of the wall behind the toilet. Have I got that right? If not, please correct me. I am finding that I do not get consistent answers to that question. If I do have that right, then I am still confused because I find that some 12" rough-in toilets installed in such a setting would result in a slightly too tight clearance between the wall and the back of the tank, (where it would put some pressure on the connection between the tank and the bowl), and with others there would be a gap behind the tank of up to 3/4". So what gives? I am grateful for any help.

  2. #2
    Plumber Cass's Avatar
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    12" rough-in means the distance from the center of the flange to the FINISHED wall is 12" which includes the trim....

    Many walls are not plumb and can cause the problem you describe...

    Many 12" rough-ins are less or more...

    Last edited by Terry; 07-04-2009 at 10:21 AM.

  3. #3
    Retired Defense Industry Engineer jadnashua's Avatar
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    There is no standard on how much space there is behind the toilet to the wall. It varies by manufacturer and model from nearly none, to over an inch. The only guarantee you have is that if the rough-in is truely 12", a 12" rough toilet should fit. There is some variation in the manufacturering process, some are more consistent than others, so the value shown on the spec sheet is also an approximation.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  4. #4
    Plumber jimbo's Avatar
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    It REALLY does mean 12". ( From FINISH wall ). In the field, you ceratinly find less than a consistent, exact, 12". Also, there are considerable manufacturing tolerances on toilets, due to the molding and firing tolerance. If you look at any manufacturer's spec sheet, they almost always show from 1/2" to 3/4" clearance from the wall, if roughed at exactly 12". This gives them wiggle room on the large side, and if a batch comes out on the small side, you could have an inch+.

  5. #5
    Moderator & Master Plumber hj's Avatar
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    Default rough

    It means if you put the pipe 12" from the finished wall, ANY 12" toilet will fit it. That does not mean they will all have the same space between the tank and the wall, however, because that dimension depends on the manufacturer's decision as to how much leniency he wants to give in case the pipe is NOT 12" but is really something less that that.

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