I am putting a storage loft in a shop/garage 30 wide by 36 feet long. The loft will be 12 feet by 30 feet across one end of the shop. I want work space under this loft so I am looking for a clear span, wall to wall of 30 feet. This beam will have to support a live load floor above it. Should the 2X12 floor joists be sit on top of the beam, or can I use hangers and place on the side of the beam? I will be using 1-1/4 inch plywood flooring on top of the floor joists.