lagrimas85,
I am having the beams made with 2" x 8" concrete base. Lifting them in place and shoring. I will have 14" of foam between the beams, covered with 2 to 2-1/2 inches of concrete. The beams are made of 1/2" rebar and are 3" x 14" high. I attached a pdf of the beam in a earlier post...