Hey guys, now that my heating system is done I am working on my gutted bathroom. I will be filing for a permit this week and be doing the work myself. I never plumbed a bathroom from scratch before so I am working at one step at a time. The sink, toilet and tub are against the exterior wall. Instead of touching the insulation and drilling holes I am building a another 2x4 wall in front of it for plumbing purpuse's. All vent piping will be 2inch's and it will be 3 inchs in the attic coming out of the roof (6 inchs of roof line). The horizontal pvc is above the sink by 8 inchs. Does this design look right? I know it is very vague, just looking at the basics right now.