Toilet trouble

hampshirebabe

So this is what I think the layout is, my neighbours toilet is directly above mine, there an airing cupboard next to the toilet with a removable back, behind that is a big grey pipe running from the floor to the top, it's this side of the wall. The vent pipe is directly about this on the outside of the building, so it must be the vent pipe and the waste pipe. So I'm thinking there must be a vent pipe from my toilet waste pipe to that one, and that's blocked. Does that sound feasible, how can I solve that?

hampshirebabe

Both toilets empty into the manhole from the same pipe and my neighbours has no problems. 

Homer_home

What vent pipe?

The soil stack is open at the top this is the vent which allows air into the system

It's entirely possible for your neighbour not to seemingly experience issues even when you do

Like I've already said you need your drain(s) checking , there's nothing stopping you lifting manholes and having a look yourself 

hampshirebabe

I've done that, thats how I know they both drain into the manhole from the same pipe and there is no problem there.
I mean the top of the vent pipe is in the wall (not the roof) directly above this. A few people said in the first picture that wasn't the vent pipe (or soil stack).