I am using X1, and am trying to add a third floor to an existing 2 story structure. The original 1 1/2" low pitch shed roof needs to stay in place. The new 3rd floor floor will be framed up with 14" I-joists, with a 4x12 beam under the I-joists but on top of the existing roof. I am at a loss. There does not seem to be much info about remodeling projects. Could someone point me in the right direction.