As most know we are building and I am getting a new shop. This is a metal building, not the kind with large I-beams. I will be adding stud walls inside only around the perimeter . I plan to put 1 x 3 around the building to attach stud wall and of coarse attach bottom plate to concrete. My question is should I attach wall to just one 1 x 3 or have a upper and lower 1 x 3?