Soil Pipe conundrum

[justin1970]

Right, the Mrs wanted the bathroom a certain way. It meant turning the toilet through 90 degrees. I've tried an s type configuration for the waste from the toilet but its ugly and takes up a lot of space, making the area look cramped, even if I boxed it in.
The soil stack outside is cast iron and about 30-40ft in height so its a massive job to cut it down for a new section....
What I am thinking is sealing up the existing cast iron at the bathroom wall end, leaving the old stack and building a new plastic stack where I want it - but I'm not sure how I go about fitting it to the bottom end.
Would I be safe in cutting the last 50cm of the cast iron off and joining the new plastic one in there? Or is there a simple way of joining a plastic pipe to the old one?
Please be gentle this is my first project and has all come about cos the Mrs wants a 10 grand bathroom on a 2 grand budget and, well.... its just not worth arguing.

 

[noseall]

if you are to leave the existing c.i. stack in place, (heaven forbid) then you are best dealing with the alterations below ground and bringing the drain in-line with the new drop.

bear in mind, that any 90 degree bends may require an inspection chamber.

or you could really bodge it and angle grind the c.i. fit a cast iron -plastic connector to the stub and have a series of bends above ground linking you to the new plastic stack.

ugly.
you may require an access connection at the bottom

 

[chrishutt]

Interesting problem. In practice I think a connection near the bottom of the existing stack might be OK if it was well swept (e.g. 45° angle) and the branch in the CI stack was above the drain bend by the required minimum (which I can't remember off hand, but it's in the Building Regs H1). The new parallel vertical stack would need venting, either by continuing it above the eaves like the existing CI or fitting an AAV (Durgo valve) internally. However your local Building Inspector might not like it.

 

[JohnD]

Right, the Mrs wanted the bathroom a certain way. ............the Mrs wants a 10 grand bathroom on a 2 grand budget and, well.... its just not worth arguing.

Get a new one.