Box Beam Design

[mai3cissie]

I am building a 28' x 48' loft - metal roofing 5/12 slope, partitioned in the center making two 28' x 24' rooms. I want to span the entire 24' and support the loft floor. I would like to keep the box beam depth at 10". I was thinking 2x6 frame (like a standard wall 16"oc with doubled top and bottom plates) with 1/2 or 3/4" plywood on either side.

Does anyone have experience with this type of design/construction? Can you give me some idea if this is close or what would I need to carry the loft / sleeping rooms (24' x 14')?

Thanks for any 'constructive' feedback.

Mark