# Patch concrete slab foundation after toilet drain pipe/flange repair



## blue (Feb 22, 2016)

Hi all, newbie homeowner here.  My toilet's flange and ABS drain pipe recently snapped off, and I hired a plumber to repair it.  The guy dug out the foundation around the pipe and fitted a new pipe and flange, but didn't refill the new hole in the slab with concrete (apparently it wasn't a service the plumbing company offered).

Seems like I could fix the rest this myself (clean out debris, pour concrete, level off, wait a few days and replace tile).  Then again, I've never patched a concrete slab foundation before.  Is it an easy fix or should I hire a pro?  

Thanks!  Pics below.


----------



## joecaption (Feb 22, 2016)

That would have worked if he did not mess up like that.
The flange is to high and is crocked.
Flange needs to sit flat on the slab floor.


----------



## blue (Feb 22, 2016)

Thanks for the response.  I just checked it and the flange is indeed cocked.  And if I lay down the new tile at an even height with the existing tile, the entire flange won't sit flush: 1/8" too high on one side, maybe 5/16" on the other.  Looks like getting the flange flush with the tile will be an issue, is there a way to shim around the flange?

I googled around and it seems whether or not the flange should be on the slab or the finished floor is a debated issue.


----------



## bud16415 (Feb 22, 2016)

Get a vac and suck out the dust and loosen up that coupler and yank around the flange a little and see if it sits down flusher. 

If not you might have to call him back. Filling the hole is no big deal. I would fill the bottom with spray foam to take up some of the space and in case you ever have to break it out again. Just mortar the top 2 or 3 inches.


----------



## nealtw (Feb 22, 2016)

bud16415 said:


> Get a vac and suck out the dust and loosen up that coupler and yank around the flange a little and see if it sits down flusher.
> 
> If not you might have to call him back. Filling the hole is no big deal. I would fill the bottom with spray foam to take up some of the space and in case you ever have to break it out again. Just mortar the top 2 or 3 inches.



The flange wants to be bolted down so I think concrete is a must.


----------



## bud16415 (Feb 22, 2016)

nealtw said:


> The flange wants to be bolted down so I think concrete is a must.



I would have thought he didnt glue the flange yet. I bet he just stick it on to keep dirt out. slots dont look like they are lined up right.


----------



## nealtw (Feb 22, 2016)

bud16415 said:


> I would have thought he didnt glue the flange yet. I bet he just stick it on to keep dirt out. slots dont look like they are lined up right.



I think the blue part swivels. Usually we see a four in pipe sticking up out of the floor and after the floor is fixed the pipe is cut flush and a 3-4 flange fits inside.


----------



## blue (Feb 22, 2016)

nealtw said:


> I think the blue part swivels.



Yes that's correct, it spins around the pipe.  I'll try loosening the coupler and getting the flange evened out.


----------



## bud16415 (Feb 22, 2016)

nealtw said:


> I think the blue part swivels. Usually we see a four in pipe sticking up out of the floor and after the floor is fixed the pipe is cut flush and a 3-4 flange fits inside.



Thats how I would do it also. Reason I wonder if he didnt glue it in yet so there would be some to cut off.


----------



## nealtw (Feb 22, 2016)

If all else fails you could start over.

[ame]https://www.youtube.com/watch?v=-42fYTzToGI[/ame]
[ame]https://www.youtube.com/watch?v=3L7w6kNIIsA&ebc=ANyPxKqzp1062utEW0iGxPCjxJY33wF4sbct4u3upApH7g65Zjrgd0_1u89PhPg6kN7lAiH5gaRX0tfDjIgP1pgGkdgdulawoQ[/ame]


----------



## slownsteady (Feb 23, 2016)

just noticed the flexible coupler. You might be able to loosen that a bit and try to reseat the flange.


----------



## Snoonyb (Feb 23, 2016)

blue said:


> Hi all, newbie homeowner here.  My toilet's flange and ABS drain pipe recently snapped off, and I hired a plumber to repair it.  The guy dug out the foundation around the pipe and fitted a new pipe and flange, but didn't refill the new hole in the slab with concrete (apparently it wasn't a service the plumbing company offered).
> 
> Seems like I could fix the rest this myself (clean out debris, pour concrete, level off, wait a few days and replace tile).  Then again, I've never patched a concrete slab foundation before.  Is it an easy fix or should I hire a pro?
> 
> Thanks!



Interesting!

It appears that the waste line is ABS, and the repair material is PVC, with a no-hub coupling. There are adhesives that are blended to join these dissimilar materials.

Loosening the no-hub coupling and lifting the closet ring to level, will raise it above the tile.

You should have the guy who did this, come back and do it correctly.


----------



## slownsteady (Feb 23, 2016)

Can't be sure from the pic if 'up' is the only way to go. It's worth the suggestion.
But yes, if the plumber just left, it is time to call him back to do it right.


----------



## blue (Mar 1, 2016)

> Usually we see a four in pipe sticking up out of the floor and after the floor is fixed the pipe is cut flush and a 3-4 flange fits inside.



Maybe the reason this approach wasn't taken is because the flange has to be on an 90 degree elbow pipe (in order to connect to the rest of the drainage pipe running horizontally thru the foundation), and there wouldn't have been enough space to get a good fit because of the curve of the 90 degree elbow.

The plumber had charged me $400 ($80/hour for 5 hours).  Quite sure I got ripped off and didnt want to deal with their bull**** again, so I decided to research it more and just finish it myself.

First I used a wire brush on the edges of the existing concrete and I cleaned up the area.  Then I loosened the coupler and get the elbow/flange level. No way to move it down closer to the floor though:








I retightened the coupler to the point where there was little-to-no give on the elbow, but did not apply any adhesive to the pipes (hoping this doesn't come back to bite me).  I ran some water down it and felt for leaks, seemed good, so I then filled it in the hole with pea stone gravel, making sure to work it in the tight spaces around and beneath the pipe:














I applied Quickcrete bonding adhesive to the edges of the existing concrete, let it dry, then mixed up some Quickcrete 5000 high strength concrete (I had extra lying around) and patched in the remaining 2 or so inches.  The 5000 has got a lot of gravel in it, so getting the top smoothed off was a challenge for me (again I'm a noob):








If I was a smarter person, I would've done a dry fit with the toilet and the new toilet flange before patching in the concrete because the room is TINY and if the toilet flange has moved by more than an inch, the bathroom door will hit the front lip of the toilet.  But I measured it, seems ok, I'll do a dry fit once the concrete cures, and use my forehead to smash the new concrete if it doesn't fit.

So the remaining issue is that the metal flange will still be a 1/4" or so above the new tile.  To secure it, I think I'm going to get some of these composite shims, and silicone them to the tile underneath the flange, and then bolt the flange thru the shims + tile + concrete with concrete anchor bolts.

Thoughts?


----------



## bud16415 (Mar 1, 2016)

I would have adjusted it as you did to get it square and then cut a quarter inch off the elbow or off the end of the flange to get it to drop. I would have then glued the joints  and got everything in position and did the gravel as you did and then patched the floor. I think I would have stuck the hold down bolts in the mix and let them harden in place. 

I hope you have enough height between your flange and the bottom of the inlet for the wax ring to seal and not hold the toilet up. That&#8217;s eazy to check turn your toilet over and lay a straight edge across the bottom and measure the space.


----------



## nealtw (Mar 1, 2016)

That should work with  the thin wax ring, the one with out the funnel in it.


----------

