text:  A designer cannot take into account every single detail of trying to tie into an existing house because they don't have the x-ray vision. You're not going to know what's going on maybe up in the roof areas until you start stripping it down and you see what others have done before you there. The builder may not even know either or the person building this, but they will figure it out as it crosses their path. That's what builders do. They've got the plans which give them the