My problem is how to fit the branch connector as I cannot see how the bottom of the connector will fit the pipe, there being no push fit connector visible above the cement floor.
Am I likely to find a connector below the floor? If not then what would I need to connect the bottom of the branch into the existing pipe?
The WC I am fitting has its outlet at 180mm above the floor, which is about the same height as the connector it would fit to on the branch, so I would need to connect this close to or below the floor (although I still have some flooring to fit, which would give another 10mm or so to play with).
I still don`t think I`ll have enough drop, so I have cut out some floor around the pipe so I can cut it off further down. Can you see any problems with this (such as having to fill it back in with cement around the connection or having the branch partially buried)?
You will almost certainly have to use one or the other as lifting the stack enough is fraught with problems.
You could bury the connector, but digging the hole and cutting the pipe below ground level is possibly a nightmare. Can't you cut the excess off the branch? It only needs to go in the pan connector about 1" which means the bend will be about 2.5" off the ground. Unless the toilet is going to be 5 or 6 feet from the stack, you should still get the fall.
FYI if you Google "toolstation.com" and then search their site for "Black Soil & Vent"
They even have a flexible equal tee.
Having had another look, measured everything, scribbled a couple of diagrams etc, I now see that the offset joint is going to be in the way (in order to get the branch at the ideal height). So I`ll have to cut off the pipe above that, fit a new offset, bit of pipe from that to the branch, then the branch into a coupling (with the stops filed off as you suggest, thanks for that idea).
Even cutting the branch down, with the coupling it`ll still be too high so I have cut away some of the floor to give me a bit more to play with (took about 20mins with my SDS drill).
I have all the bits I need on the way so I can get stuck in to this job this weekend. Then get on with the partition walls (which, apparently, have to have sound insulation in them, and also have to be inspected by building regs before finishing).
Do you think it would be useful to others if I was to post a photo of the finished pipe (assuming it`s not an embarrassing mess)?
The original offset joint has been retained as it proved to be in good condition, and a very tight fitting push-to-fit type too. It has been moved up to accommodate the branch.
The bottom of the branch is just below floor level, as otherwise there would have been a slight rise from the toilet itself (although I do still have the floor to fit, which will raise the toilet slightly, I just wanted to be sure I had a drop from the toilet to the branch). Of course I therefore had to cut away some more of the floor to get the connector in.