I need to put up walls for a bathroom in my shop. I can build the 4 walls, but is there a preferred or required layout for butting the walls together at the corners? 2 opposite walls inside the other 2 walls, or overlap each corner differently, or ?? Also, the sewer (stack?) pipe is sticking up from the floor and should be inside one wall. What is the correct method to cut-out the plates for the pipe?