12-inch toilet installed in 10-inch rough-in

[lazerdriver]

I am remodeling a bathroom in my basement, the home is about 33 years old and I am the second owner.

Before removing the existing toilet I measured from wall to toilet floor bolt centers and it was about 12 inches. Based on that I purchased a new toilet for a 12-inch rough-in. When I removed the existing toilet, I was surprised to find that the rough-in was 10 inches (actually 10.5 inches from wall to center of the floor flange opening).

So my first question is how did this ever work at all? I have never had any clogging problems in the 15 years I have lived here. The existing floor in vinyl over concrete and I have never seen any sign of leakage. I don't know plumbing code, but it seems like it would be a violation of some kind. It seems irresponsible of the installer. I doubt they were installed the previous owner, based on my observations they did almost nothing to the place in the 20 or so years they lived here. There are two more of the exact same 12-inch toilets upstairs that I will replace eventually, so who knows what I will find for rough-in when I remove them.

The obvious fix is to get a 10-inch toilet, which greatly reduces my options, and I will probably go that route. But I can't help wondering...has anyone heard of an installation like this before? Would it be a bad idea to try to install my new 12-inch with a 10-inch rough in? I'm guessing yes, yet somehow it worked before...

Also I read that I could get an offset flange, but some reading said these are not code. Is that true?

 

[Reach4]

There are some 12 inch toilets that have some extra space behind. https://terrylove.com/forums/index.php?threads/toilet-rough-in-size.86565/#post-620995

Mounting the toilet a bit off-center can be OK, since the output hole is smaller than the input hole.

Another factor can be the tilt of the wall. If the wall tilts away, you would have more space behind the tank.

Also I read that I could get an offset flange, but some reading said these are not code. Is that true?

No.

 

[Sponsor]

 

[Jadnashua]

The designed space behind a toilet is not a standard, so you'll find if you look carefully, some are quite large and some have the back nearly on the wall...all that rough-in spec means is that should you have say a 10" rough, and buy a 10" rough toilet, it will fit...not how much of a gap there will be behind it.

You can fudge the location of the toilet over the flange by maybe as much as 3/8" or so. It's probably not a good idea to have the back of the toilet actually touching the wall, as if it is used regularly, the incoming cooler water may cause condensation, and that could trap moisture behind the tank and promote mildew. Today's, lower-flow toilets usually don't flush all of the water in the tank, so there's often some room-temp water in there to help warm up the incoming water, so it's much less of an issue UNLESS the thing is flushed frequently.