Best way to permanently plug a lead closet flange

Users who are viewing this thread

Not a Pro

New Member
Reaction score
New Jersy
Hi guys, got a problem that needs to be addressed ASAP............... Don't they all?

My home was recently elevated and 95% of the plumbing was redone (all above the slab) and all routed through the same cast iron soil pipe (below slab) with an exception being the old toilet closet flange (embedded in slab).
The old toilet had a lead closet flange coming up through the slab floor. It looks like this is sleeved into the cast iron below the slab. I tested with a magnet and the first 8-10 inches appear to be lead. This was capped after the renovation but not effectively as this area under the current house just experienced a leak at this location.
At this point this closet flange is not being used and from what i can tell the soil pipe does not appear to be blocked. Drains currently operate fine. I think the problem occurred when a washing machine (floor above) discharged and a large volume of water/air/soap was sent down the line. There is a check valve just in front of the house which is about 15 feet off the main stack which may have impeded the flow and caused a back up in the storage area under the house.

At this point i am looking for the best way to plug or cap this closet flange so that back up doesn't occur in the area under the main living space. The old lead closet flange is deformed and measures 4 inches wide and 4-1/4 inches long so it is not circular, more oval shaped. When the toilet was last in use the toilet flange was hodgepodge of an ABS compression flange and silicone and from what i remember the toilet would gurgle from time to time. I tried the Oatey 4" test plug but it will not seal because it is not a truly round opening.
I dont want to take on the job of removing the lead insert and since i don't use this terminal if it's easier to just plug the pipe with something, concrete, expansion foam etc.
Incidentally this closet flange sits about 4 feet off the stack in the opposite direction of the check valve in front of the house. It is also the lowest drain in the house.
View attachment 39156 View attachment 39157 View attachment 39158
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks