Strap on boss entry through cavity wall

[mike42]

Due to previous owners doing stuff to the house (joining original house with garage and room above), we have an internal cavity wall with an existing soil stack on the original inside. I would like to be able to connect a 40mm or 50mm waste pipe into it from the other side of that wall.

I'm thinking the neatest would be if I could connect directly through the wall and into the stack but that seems like it might be very hard and would need a hole the size of the boss itself to be drilled (no big deal I suppose but then the rest of the fitting might be hard?).

The other option I can see would be to fit a boss as normal pointing parallel to the wall and then fitting a 90 degree elbow to accept the pipe from outside.

Which of those two would be better or is there something I haven't thought of yet? I've never fitted a boss before so I'm trying to imagine how it would be based on reading lots of stuff here plus youtube etc.

Any thoughts much appreciated and if its not clear I'd be happy to take a picture or draw something.

 

[Hugh Jaleak]

A picture tells a thousand words. All depends what room you have though, you need a 54mm hole in the soil pipe to accept the boss, so you have to be able to get a hole cutter of that size into the correct position. If fitting sideways is easier, (particularly for a first attempt), then do so. Last thing you want is a boss you cant get to, leaking.

 

[Nige F]

Do it on the side but put a T with an access plug instead of the 90. then you can clean all the way back down the waste

 

[mike42]

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