There is an old bathroom in my basement that I am trying to get back operational. Buried and surrounded by the concrete floor is a piece of ABS pipe that has a 3.5" ID. It is about 2" below the top surface of the concrete floor. It was used as the waste line for an old toilet. I need to find a toilet flange with a tailpiece with a 3.5" OD to fit into this pipe. Either push & repair or glued, I don't care. I've googled my ass off but am not getting anywhere. Where can I find such a beast?

Are you sure that wasn't just a floor drain?
I have not seen anything but 4" for toilet flange.

You can chip out the concrete around the pipe - careful not to break the pipe - and set a 4x4 or even 4x6 cast iron flange over the ABS. Pack and pour or caulk the flange to the ABS.

Yes, you can extend the pipe with a short piece and a coupling with enough prep work, and use an I.D. compression flange, but it seems like there would not be much for the flange to grab upon.

Can’t you just use an adjustable flange?

They make them for that purpose, sometimes called repair flanges, take your ruler and check the local big box or plumbing supply.

Here is one that is 3" ID so it will be close to your needed 3.5" ID pipe on its OD.


OOPS... forgot the link

https://www.lowes.com/pd/Oatey-ABS-Flange/50315023

This message has been edited. Last edited by: cparktd,

I'd suggest going to an actual plumbing supply store and tell them what you're trying to do. It will cost you a few buck more than Lowes or Home depot, but you'll be better off.


"What your measuring is the inside of a 4 inch drain. It is very normal for a plumber to install a 3 inch female toilet flange 3.5 inch outside diameter into the 4 inch pipe.
Get the same plastic and use a lot of cleaner and glue on both. Also buy a flange with the stainless steel ring."

https://www.diychatroom.com/f7...de-fit-3-5-a-346673/

Thank You all, cas that explains it. I did take a ruler to lowes a couple weeks ago and all the repair flanges were either 3.75 or 4.25". I tried pushing it into a piece of 4" but no way it would fit. I saw that a 3" pipe was 3.5" then I could use a 3" toilet flange and connect the two with a small piece of 3" pipe. I was just looking for a flange with a tail that would fit down inside the abs drain pipe. Thanks again

If you are a daring, forward-thinking plumber (risk-taker), you could glue a piece of 3" PVC inside the 4" pipe and us a 3" glue-on flange.