Toilet flange not attached to anything except the drain pipe

[Canada_DIY_Plumber]

I'm putting in a new tile floor in the bathroom (was sheet linoleum before.) I need to add an additional layer of plywood underlayment and then the tile and so my toilet flange will be too low. I was planning on using an extension kit (the spacers) to bring it up to the new level of the floor but I just noticed that the existing flange is not attached to the floor at all. The hole in the plywood is almost the same size as the flange. The existing ABS 4" drain pipe comes up through a concrete floor and the toilet flange is attached to that with solvent. The floor assembly is about 4" tall (2*4 sleepers resting on concrete with a 5/8" plywood floor on top and so the flange is sitting about 4" off of the concrete. FWIW, it feels very solid. It doesn't wiggle around at all.

I think I have three options:
1) Ignore it. Just add the spacers and move on.

2) Cut out the wood around the existing flange. Then put some 2*4s and any required shims directly underneath it (that would be attached to the concrete floor) and screw the existing flange into those 2*4s so that it is properly supported/restrained. Then use an extender kit to get to the height of the new floor.

3) Cut off the existing flange which would leave just a little nub of 4" diameter pipe above the concrete. I would install the new plywood underlayment with a smaller diameter hole, and then install something like this which would sit on top of the new layer of plywood and would be attached to that layer. I'll have to measure carefully to make sure it is long enough with this option. I'm worried the push-tight adapters won't have enough reach.
https://www.homedepot.ca/product/si...oset-flange-by-for-4-inch-dwv-pipe/1001201162

Any thoughts on the best course of action?

 

[Jeff H Young]

2x4 blocks under floor for backing whatever you can get to get minimum 3 good screws in but 3 is cheesy work get at least 4 the more the better. with plenty of penetration

 

[Sponsor]

 

[Tuttles Revenge]

You definately want the flange screwed down to the floor.

 

[Reach4]

The existing ABS 4" drain pipe comes up through a concrete floor and the toilet flange is attached to that with solvent.

You could cut off the toilet flange, and extend the pipe.

Is that an outside closet flange that is glued on? There is another fairly-easy alternative in that case.

 

[Mr tee]

There are several types of long closet flanges that fit inside 4" ABS. You could just leave what you have and use one one of those and fasten it to your new floor.

 

[Jeff H Young]

Whatever you do get good backing in there before your new plywood. Drywall screws in the plywood aren't stout enough and not good workmanship. That's why you get real wood underneath first.

 

[Canada_DIY_Plumber]

Thanks all. It sounds like the best option is to:
- Cut out the existing set-up about 2" off the floor.
- Glue on a 4" coupling
- Glue in a short section of 4" pipe
- Glue in a male 4" toilet flange that will sit on top of the new tile floor
- Screw that flange securely through the tile/sub floor