I am working on planning some plumbing for a timber framed home in NJ. I will be owner/builder and have done a good bit of plumbing but I am no expert on code. We have a couple desired fixture locations that create some venting issues and I am hoping you can help me to understand something in the NSP code book. My question is regarding 12.8.1 exception 3, what does it mean? All of the exterior walls will be foam cored sip panels that plumbing cannot run inside of. Further more, the entire exterior of the house will have large, exposed timber beams supporting the second floor structure. So, any fixture on an exterior wall is essentially impossible to vent from above without building an undesirable plumbing chase. Please see the bathroom drawing and the code excerpts below. I am sorry the drawing is not very good at this stage.. I am just working with general ideas at this point then I will refine the specifics.