hello all pretty new to the forum and was after some advice. I am fitting a new bathroom/wet room in a house I have just bought and wanting to move the waste thus putting a new length in and a boss onto the 4inch soil that is set in the concrete floor. My question is am I ok to run the 1 1/2 pipe from shower to pick up the bath then into the boss a length of about 3 metres concreted int the floor or should I extend the 4inch as far as I can under the bath and shower then just drop down with the smaller pipe into the 4inch.??? Would it make a difference either way? I have taken the concrete up in the room as to get the wastes where I want them.