Boy am I glad I found this forum.

I have just put up a 50X50 pole barn near Minot ND and I am going to frame in a shop in one corner. I would like to make a free span 25X25 insulated and heated shop. I'm trying to figure out how best to support the ceiling. The loft area above the shop will be a storage area. What I will probably do it put a beam across the center of the room and use 2X12 rafters to span the 12' 6" from the center to the outside walls. My problem is trying to figure out what to use for the center beam and how big it should be. It would be a 25 foot span. Would it be better to go with a steel I beam, Glulam or engineered truss, and how big they should be.
Any suggestions would be appreciated.
Bob

Steel would probably be the simplest, cheapest, and have less depth than the other choices, and would be the lightest, with the possible exception of a truss.

Glulam is possible, but we are talking about the kind of glulam that is made up of 2x6 or 2x8 laminations. It would be quite deep and VERY heavy.

A truss is also a possibility, but again, it would be deep, probably the deepest of all three.

Don't forget that "storage" must be designed for something in the order of 120 lbs. per square foot live load. Also check your local building code for any fireproofing or fire separations required.

I do not think it is ethical or proper to design structural members on this forum. A designer MUST be aware of ALL conditons, and ALL code requirements, before any design can be done. For example. you may need some fairly big footings under the posts at the ends of such a girder. How will this be accomplished inside an existing building?