We have a 1945 home and the rough-in is 11.5". We purchased a 12" toilet being told there was some leeway. However, there was none. We don't want to purchase another toilet and not be able to use it.

While we (my husband and I) didn't quite understand it, we were left with the impression that there was nothing to be done but to install a 10" rough-in toilet thereby having a 1.5" gap behind the toilet. I'm not crazy about that idea. I did find a few toilets that would work with an 11.5" rough-in, but they were all too large for the minuscule bathroom.

The drain pipe is iron and a scant over 11.5" from the finished wall, not including the base board and is about 3.5" diameter.
https://u.pcloud.link/publink/show?c...2CwN8UruPpnXW7
(if the image doesn't show, you can download it)
https://u.pcloud.link/publink/show?c...JDuBoHBjaMPJOX
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We don't have much room to work with and one thing we can not do is tear up the floor. We probably can enlarge the area around the drain somewhat, but that's all. Because this bathroom is in the attic, under the eave and next to the garage crawl space, changing any plumbing would require not only removing the floor in the bathroom, but also the floor underneath it which is the ceiling of the bathroom underneath. That area used to be a shower and it has cement that would have to be removed. Then the pipes run into the garage crawl space, which would require removing part of the roof to get to them ... so, we need to find a solution that doesn't involve tearing up our entire home and even if we were willing to do it, couldn't possibly afford it.
https://u.pcloud.link/publink/show?c...AqMhVYzY4KBKR7
(download image)

Note: I saw a similar post in this forum, but failed to understand how that person resolved it.

Can we use an offset flange?
What kind?
How do know what size to select?
What would we need to do to install it?
Anything else we need to know?

You will be looking for an offset toilet flange. If you have a local plumbing supply store, you can probably take a few pics and go there. They'll get the right flange for you and likely tell you how to install it. I'm not a plumber so I'd be hesitant to offer my installation advice.

This will give you a general idea of how to do the job. This man seemed to be facing your exact situation.

https://www.youtube.com/watch?v=rLAlhkQPrjM

Hi B

If this is a two-piece toilet (tank and bowl), you should not be having a problem...all two-piece toilets fit an 11.5" rough in from finished wall. If this is a one-piece toilet, then 11.5" should still work but it could be tight. You have suggested that you have a 4" cast iron drainpipe and flange. If that is the case, then you should have no problem installing a two-piece 12" rough in toilet onto an 11.5" rough in from finished wall. Here, you just need to pull the toilet bolts in the flange forward a little and you should be able to install the toilet without interference. Worst case, you could drill the cast iron flange and enlarge the slotted holes to move the toilet bolts forward. If none of that floats your boat, then you are stuck with installing a 10" rough in toilet.

In terms of an offset flange, an offset flange will only work if the cast iron pipe itself is at least 3" below the floor. Here, an offset flange is pretty deep, and the old flange would need to cracked off the old drainpipe and then the offset flange would need to be installed and LEADED in with lead an oakum...this is not something a homeowner would ever attempt by themselves.

If this was PVC, we may be able to talk you through an offset install, but even then, it is quite involved.

Back to you,

Mark

Thank you. When our plumber returns from vacation I'm going to run this past him.