I have a 1972 built home that has cast iron drain pipes. there is already a rough in for a toilet. it is a cast iron hub on a 4" pipe. The hub measures around 5" across on the inside. the top edge of the hub is actually 1 1/2 inches below the concrete floor. I tried to use a Fernco multi-tite gasket (donut) and a piece of 4" schedule 40 PVC to give myself a pipe to put a flange onto. The gasket fit into the hub fine, and the gasket would fit onto the 4" pvc fine, but when the gasket was in the hub I could not get the pipe to go into the gasket. I beveled the edge of the pipe and used half a bottle of dishsoap to no avail. I then tried to put pipe in hub first and then drive the gasket into space between hub and pipe, but it only went down a short ways and stopped. I thought it would work so I glued flange to pipe and glued flange to concrete floor with some polyurethane construction adhesive (more on that later) Waited 24 hours and pried on toilet flange to see how tight it was and I pulled flange up along with the pipe. So, gluing flange down and the way the fernco was half-assed installed didn't work. So, first question is what should I do?
The other problem is that this hub which has a 5 1/2 outside diameter is surrounded by a another pipe. It looks like when they were pouring the concrete for the floor they put a steel pipe over top of the flange to keep concrete off of it. So the problem this creates is there is no way to screw the toilet flange down. There's only a part of the very outside of flange ring that rests on concrete. So, second question is how should I fasten the flange down when I have nothing to screw it too?
The other problem is that this hub which has a 5 1/2 outside diameter is surrounded by a another pipe. It looks like when they were pouring the concrete for the floor they put a steel pipe over top of the flange to keep concrete off of it. So the problem this creates is there is no way to screw the toilet flange down. There's only a part of the very outside of flange ring that rests on concrete. So, second question is how should I fasten the flange down when I have nothing to screw it too?