I don't have an answer to your question, but see you said you are going by "NJ code (national standard plumbing code)". I'm a DIYer in NJ and did some work years ago (2002-2003) and my town told me to go by UPC. Now I'm starting work again (new bathroom)... I assume I'm still under the UPC. Of course I think each town could supersede the states requirements. Since you brought this up, I'm going to double check with my town and see which code they will be inspecting me on this time.