My main discharge stack in my bathroom is a couple of feet away from the wall and there is a 110mm vent stack going straight up into the loft. Because of this, quite a large part of the corner of the room is boarded up. I would like to create a bit more space and put a shelf in and wondered if i can remove the vent stack, put a couple of 45 degree bends in and relocate it right in the corner. Is that allowed?