What Does Rough-In REALLY Mean?

Discussion in 'Toilet Forum discussions' started by jbell94521, Jul 4, 2009.

  1. jbell94521

    jbell94521 New Member

    Messages:
    5
    Location:
    Concord, CA
    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. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    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...

    [​IMG]
    Last edited by a moderator: Jul 4, 2009
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,266
    Location:
    New England
    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.
  4. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    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. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,047
    Location:
    Cave Creek, Arizona
    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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