i am planning a conseratory and my soil stack sits smack bang in the middle of the rear wall where i want to put it. it is a single stack house (everything branches into it). my idea is move the stack 1.5 metres to the left close to the corner of the house. smaller bore pipes branching into it from bathroom and kitchen sinks would just be extended, upstairs toilet would be better as stack would now sit directly outside the toilet wall and the toilet wouldnt branch into the stack like it presently does. but my question is can the stack run vertically down to just above ground level then across under the back door and into the existing opening to the drain?