Steel Joist
Steel is 100% non-combustible, easy to handle, mold resistant, strong and easily fabricated
Pre-engineered and pre-fabricated by truss professionals
Wood Truss
The wood truss roof is built with the beams in an A shape overlapping the bottom beam. Beams running from the top to the bottom add support. The trusses are shaped like a big A and a little A, and are secured with braces, usually metal, for added strength. Each truss is made until there are enough to build the roof.
Rafter
normally leaves the center of the roof void fairly open, whereas the standard design of roof trusses obstructs the space.