I am about to tile a bathroom floor. I was dry-fitting some concrete board when I realized I don't know how the toilet will reconnect once the floor is higher.
The old floor was a thin layer of vinyl adhered directly to the subfloor. The new floor will be roughly 1/8" thinset mortar + 1/4" concrete board + 1/8" thinset mortar + 1/4" tile. So almost 3/4" higher than the old floor.
The PVC toilet pipe is 4" interior, 5.25" exterior.
The bad news: it's an offset, something like this.
It had a broken metal flange permanently attached to it. I have already broken away the flange.
It looks like people who are tiling usually do one of two things. Sometimes they leave the old flange on the sub-floor, and use some extension system like Set-Rite to raise the height to a second flange.
Alternatively, they just install a flange on top of the tile, and some sort of gasketed pipe descends into the old, lower 4" PVC pipe.
But what about the offset? Because of it's angled, funnel-like shape, I can't just run another pipe into it, can I?
I feel like I should cut the PVC below the subfloor, and reinstall a new offset valve higher than the old one. But space is cramped beneath the floor, and I'm afraid I'll make things worse.
I saw some videos online about separating PVC with extreme heat, but I'm afraid of igniting my house or sewer gases (I have a septic tank) or both. I have minimal PVC experience.