Neighbour wants to use vent stack for new bathroom

[Guynextdoor]

Hello,
Hoping I can get some advice please.

I live in a terraced house and my next door neighbour has begun a loft conversion using the same company who completed mine 8 years ago. (Apologies for the google streetmap pic as I'm away at the moment, I can take more pics when I'm home.)
In the pic, my house is on the left with my neighbour's on the right. They have started a dormer loft conversion and were originally planning to incorporate a wc in the loft with a macerator toilet and sink existing waste through their house to join their downstairs bathroom at the back. Their current bathroom joins a shared underground drain on my side via a man hole in my garden.
They have now decided to incorporate a full bathroom in the loft and have informed me that they would like the waste pipe to join to the vent stack at the back of the house. This is a steel pipe that runs the height of my house and has nothing connected to it apart from the small guage waste pipe from my loft wc macerator and sink and is what I considered just a vent pipe (its the black pipe on the right). I also take their roof water to a drain which is the plastic pipe on the left)

I'm thinking of doing a full width kitchen extension and this may result in reconfiguration of the drains. If I do, I also don't want their loft waste to drain into the vent pipe within my new kitchen if it remains, when they could make use of their existing underground connection to a shared drain via manhole.

My question is, can the neighbour insist on connecting to my vent pipe as it is on my side of the boundary and they are currently not using it at all.
(They are suggesting it is shared and on the boundary.)
If they have access to shared drains for their existing downstairs bathroom via a manhole, should they not use that and handle their loft waste internally to their house ?
What are your thoughts on where I stand please?

Thanks in advance.

 

[Mike13]

It looks to me as if it is on your side of the party wall, but only just. It might be shared, who installed it? was there some of the pipe there before you started your roof extension?

 

[Guynextdoor]

Yes it's on my side of the party wall as the neighbours ground floor kitchen extension marks the boundary and the vent pipe in question runs to ground level to the left of their extension when looking at the pic.
The right hand vent pipe was probably done in the 70s or 80s when the ground floor bathrooms were put in to replace the outside loos ! Originally it went to the roof eves level as a vent and then a plastic extension was added when my loft dormer was done 8 years ago (left hand side of pic)
If the pipe is on my side of the party wall and only used by me, does that mean they can't insist on using it ?

 

[jj4091]

It looks to me as if it is on your side of the party wall, but only just. It might be shared, who installed it? was there some of the pipe there before you started your roof extension?

That is strange as I thought it appeared to come down from the exact middle of the party wall visible on the roof. Perhaps it is the angle the pic was taken from. Not that that is much help. The only thing I could suggest if you think there is going to be conflict is to build up to the side of it rather than on the boundary, but you still will not know which direction the drains run once it gets underground until you dig out the footings for your extension. Is there an inspection chamber and if so whose land is that on

 

[pcaouolte]

Have you explained to your neighbour that you are planning to move the stack in preparation for your kitchen extension?

 

[mattylad]

It's a no from me.
When it gets blocked who pays to unblock it?
who pays to maintain it?
who pays to replace it when it rusts away?

Neighbors are often mentioned in that they do not want to pay for shared services.

Given that you have plans that will mean a total change to the stack in the future (and plans only need to be plans and do not have to actually happen) then that will complicate things further at your cost so get them to sort their own stack out now.

 

[Hugh Jaleak]

If it's on your property, they have no rights to use it, assuming it was purely installed as a vent stack when the houses were built, and doesn't look like they've ever had any connection into it. Even if they connect into the drain below the stack, I don't think that would give them any claim on using it.

Note, it'll be cast iron, not steel, and if you're planning on removing it for your extension, some form of replacement will be needed, it was fitted for a reason. Secondly, I would want to ascertain its condition before making any further connections, integrity of the pipe, and condition of connection to the drain at the bottom.