So....initially i was hoping to catch the stack but its on a different wall. So, now, we have decided to not box anything in and trench and bury the drain and supply lines using PEX So, I am wondering if there is anything I should be looking out for when my contractor does this? P traps, vents, etc. Going to have washer box inside back wall. Supply lines come up from along the inside because the back wall is an outside wall. Close up drain in center of room and move it back where the doors will be in front of the washer and dryer as well as cut and cap old washer tub drain (left). Anything out of the ordinary I should keep an eye out for? My guy seems capable but I always like to be in the know.