exception to the rule about not using inside coupling closet flange on 3" ABS?

Elbow of my 3" ABS rough-in is too close to surface of slab, and even too close to surface of finished floor (ceramic tile over schluter ditra, over electric floor heating grid), to allow outside fit closet flange to seat properly. 3" inside fit closet flange is available locally, but I've seen them panned & not recommended on forums here & elsewhere. Problem is the only other option I see at this point is hammering out my floor to re-set my ABS with a lower drain angle to get elbow to sit low enough (not sure till I get the floor open if that would leave my drain slope too shallow & cause problems there anyway)

Is my situation the reason these second-best options exist?

Any ideas other than inside-fit flange or hammering out the whole floor? I wondered about trimming the bell on my outside fit flange, but it looks like I'd have to take off an inch or more, and I don't know how short an abs joint can get before you run into problems.

What you should have done was used a 4x3 closet bend.

If the floor is done I would finish with the inside fit flange, and if were really causing me a problem down the road, I would deal with it then.

The outlet of a modern toilet tends to be 2-1/8" or less.
I wouldn't worry about it.
The inside diameter of what you are suggesting is much bigger than that. Go for it.


Sioux Chief 888-ATM
Inside Fit Closet Flange