I have a U-shaped covered porch (3 walls existing, 1 open) and am enclosing the 4th wall. A 4 x 12 beam spans this 16-foot opening (with a center post). Floor joists for the floor above sit on this beam. I want to frame in this 4th wall but can't figure out how to manage the framing to "meet" the beam and still keep the floor joists in their existing place on top of the beam. Thanks for any help.