Advice on toilet flange in concrete slab

[yeoman]

Hello. Thanks to everyone for participating in this forum. I have really gained a lot from truly informative forums such as this one and appreciate it.
My downstairs bathroom of my concrete slab house in Cali - had a super rusted metal ring flange under the toilet. Everything is out and I've posted photos.
So the top there flares out and it the sewer entrance - it has a little stepping in it - and I can't seem to feel the connection point of the PVC flange at the top at all - it's totally smooth inside at least 7"+.
In the other photo - you can see the void area is pretty large - and it's pretty deep and goes down probably 12" or more. I figure the slab is 5.5" or so so it goes past the slab.
I tried to show the height of the opening, but on one side it's about flat with the tile while on the other 3 sides it's slightly higher - and in the back it's about 1/8".
Solution?
I would prefer not to cut this old top off but will do it if that's really the solution I need to go with.
In order to drill the new flange into the cement I believe I need to fill in the void - there is a little shelf part in which the top space is close to the funnel/flange area, but underneath it's fairly open around the pipe - maybe 3/4" around. In order to fill my understanding is code says to wrap with Styrofoam - there is some there from the original install. but I can't really reach that area without chipping away the top.
- Do I chip away the top to get proper access and do I need to wrap with Styrofoam? Then do I fill with sand so that I only need to pour in 3 - 4" of concrete? I assume I flatten concrete around the existing flange to enable the metal ring to be flat against the cement and wrap around the PVC flange itself. (the ring fits fine and I have tapcon screws, etc. ready to go)
- the other option to fill the void with sand by filling a bag and funneling it in there, then doing the same with cement - like cake frosting - and just blowing off any additional styrofoam because there isn't likely going to be significant expansion/contraction of the PVC there since the contact between the cement and PVC is only a few inches.
- Are 2 1/4" tapcons overkill? Because the slab is expected to be > 5" I figure that length should be ok.
- Is it OK that the flange is flush with the tile on one side? Or, should I get a flange spacer and install that on top of the new metal ring - then screw through both and use silicon to help seal everything up? I understand that ideal the flange is higher than the tile by 1/8" or so.
- or should I get one of those extenders, so I could put an extender on top of the metal ring once it's installed?
- another option would be not to use the metal ring and instead use a flange with a spigot or with another tub that fits inside? My understanding is that you don't want to narrow the pipe - but because there is a little shelf in the pipe flange opening - I could probably find one that fits in and over the old one without narrowing if that makes sense (worst case I could cut the new pipe part down so it matches the old one.

Any suggestions would be great - cause I've spent a lot of time researching and all that to try to figure outu something that will work well.

Thanks in advance.

 

[Reach4]

You are not the first to show photos of a rag etc.
Try removing the white plastic, and then try lifting out the black plastic under it. Let's see the cast iron.

 

[Sponsor]

 

[yeoman]

You are not the first to show photos of a rag etc.
Try removing the white plastic, and then try lifting out the black plastic under it. Let's see the cast iron.

Sorry, that is a good point.

The house was built 2002 - so it's slab and black PVC. Pushing that flange barely moves it.
Thanks.

 

[yeoman]

 

[Reach4]

I had suspected cast iron under there. But black plastic will be fine. Are there slots in that flange that are gunked up? Anyway, you may choose to not use the slots.

DANCO Model 10672X is Hydroseat. It may fit your needs. You would not use the old slots. Read up on it. You put a normal wax ring under it. I used to think you put another ring on top, but I see they are planning that you just put the toilet on top with no top wax. This would fit cases where the feet are going to be on top of the finished floor, and you can drill holes for screwing down the feet. You can alternatively use the holes not on the feet to hold it down. That way you don't have to drill your hard flooring.

In your case, the feet may not all fit on the tile. In that case, I would put a spacer under those feet, such as a scrap of tile of the right thickness.

 

[yeoman]

Hi, Reach - thanks for your response. There are no slots there cause that flange used to have a metal ring around it that corroded away that I removed (it wasn't installed properly). I did check out the Danco and I saw that it was an option with good reviews. Maybe I will try it. I would have probably chip away the tile and fill in with additional cement and level it out before to ensure the hydroseat was at the right height at the end. That way I only have to drill into cement instead of tile with a masonry bit. I would maybe put another wax ring on top just to be safe. It's too bad it's not stainless, but I've been reading it seems super solid anyway. My main concern is really the fact that the front is flush with the tile while the back is about 1/8" above - and while I realize the wax ring would probably help to ensure there wasn't a moisture issue, I'm a little paranoid, but love the idea of not having to cut out the current flange. I'm sure any of the main options would work. I'm still overthinking it I'm sure. Thanks, again.

 

[Reach4]

I would have probably chip away the tile and fill in with additional cement and level it out before to ensure the hydroseat was at the right height at the end.

Where the tile is, you would just set the foot with no screw. To hold the Hydroseat down where the leg sits on the , you would use a screw through the more inside hole. If there is no inside hole where you need one, drilling a new hole through the Hydroseat steel should not be nearly as hard as porcelain or even ceramic.

There is also the possibility of using mortar to raise the hole, and put a split repair ring around the plastic, or maybe an non-split repair ring would work. But the Hydroseat has the legs. Maybe self-leveling concrete/compound would be good to level things out. https://www.usg.com/content/dam/USG_Marketing_Communications/united_states/product_promotional_materials/finished_assets/durock-self-leveling-underlayment-multiuse-submittal-CB516.pdf says it is ok up to 3-inches thick, which surprised me.

 

[yeoman]

Thanks, Reach. I have filled in as much cement as I could then I will go with the Hydroseat -that I will pick up tomorrow and see if it fits alright in my setup.