I am adding a addition to my home. The ceilings are low only 7'4". I am building the addition the same hight. I want to install a double door one side fixed in place. There is only 5" of header room and the rough opening is 81" wide. Will the header width be enough to support the rafters above? The rafters are 2' on center and there will be three to support. I am going to make the header out of two pieces of 2x6 with a piece of 1/2 plywood between them.