I used 2x6 for the walls so I could have R19 insulation. 2x6 walls are not all that common in Alabama for construction. It adds a little cost but I would just rather have a lot of insulation. Typical OSB sheets and house wrap. 9'-0 ceiling height. I will say a 24' long wall with OSB on it is heavy - I had some help standing those up.
http://s173.photobucket.com/user/Ste.../library/Walls
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