Making a girder from 2X12 lumber
I am planning to build a 24 X 26, gable entry, 2 car (double door) garage with a 12/12 roof pitch so I can use the loft area for a studio. My idea was to run a 26 foot girder down the center to support the ceiling joists. My question is, if I make a girder by sandwiching 2 X 12 lumber, "what is the maximum span without using intermediate posts for support?" I know it will depend on the anticipated load in the loft area so I would like to be on the safe side. Can I do this with 2X12 stock? Or would I be better off purchasing an engineered or prefabricated girder?
Thanks for your help!