What size beam do I need to span 24' across a garage? This beam will support 2x6 by 16' roof rafters, 16" on center. The roof will be metal and 3/4" plywood. Home located in Florida, no snow load issues. This house is block wall construction and the existing beam is a 3' tall box truss with plywood on both sides. I want to replace it with something shorter height wise. The garage is set about 3' lower than the house and the rafters are an extension of the roof beyond the house truss system. This beam will be perpendicular to and btwn the house truss and garage roof. I would like to use double 2x12 by 24' pine with plywood sandwiched btwn, but am concerned about sag. Do I need to use a microlam beam? If so what size?

Thank you
SP