What would the plumbers do here? I need to get the waste up the back of the wall rather than up through the floor. Access at back of wall is easy, lots of room in the solum. Problem is I have a double 5x2 joist underneath the wall between waste pipe connection in main soil pipe and where I want to run it to. Is it acceptable to cut a 35mm hole in a joist that sits across a 1.6m spanView media item 106106