I removed some bathroom tiles and much to my disappointment, the person who laid this out years ago did a horrible job and I’m now left with this mess to fix.

I’ll be adding a 2 inch foam base (concrete basement) and a 3/4 inch plywood subfloor.

I’m thinking about grinding this mess out and filling out a 2 3/4 inch thick concrete “block” where the new outlet pipe will sit on. About 3-4 inches wider than the outlet bracket so that the foam base and subfloor will be level with the block.

Hope this makes sense.

My only question is how to extend/raise the outlet pipe - I don’t want to dig out all the concrete, but feel it may be better for foundational purposes. Is this the correct approach?

Any thoughts on this would be appreciated as I really dont know how to fix this.

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  • What size is that pipe? For some reason it doesn't look like a 3". – isherwood Sep 25 '20 at 12:48

I would absolutely be cutting concrete. You have an ideal opportunity to do so since you're overlaying the floor anyway. You don't want to deal with clogs later due to pipe reduction from an extension, and you want the stability a proper flange provides.

Rent or borrow a diamond saw, cut out a 24" square, and fix this up right with a full-size pipe. Mix up some bagged concrete and pour it to the level of the new subfloor for a stable base (just as you describe). Use strips of the foam and sheathing as a form.

  • I have an angle grinder with a diamond tip saw. How far down would I cut? And what is the best method of joining new outlet to the old? (I assume if I’m cutting the concrete I’ll be able to add an external coupling to joint the old to the new?) – Tchai Quentin Sep 25 '20 at 13:19
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    New questions aren't appropriate in comments, especially on resolved posts. Ask a new one once you see what's in there. Your grinder won't do the job. You need to cut at least 4" deep unless you want to use a hammer drill or something else to get through. – isherwood Sep 25 '20 at 13:21

you want a toilet flange extension, this is a standard plumbing part.

This is an example of an extension that seals to the I.D. of the existing waste pipe and gives you bolt-up capability at a new higher floor level. Not a product endorsement...

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  • Yes, I think in this circumstance (contrary to my usual low opinion of toilet flange extensions) an extension is your best option. – Jimmy Fix-it Sep 25 '20 at 5:21
  • It's worth noting that this dramatically reduces pipe diameter for the length of the extension. I'd replace the existing flange if at all possible. – isherwood Sep 25 '20 at 12:47

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