what is the difference between beam and joist?
 Joists can be metal, steel or wood (Most cases are wood) and can be used for floor joists while Beam foundation  requires wood joists to span an area and provide something to fasten the sub-flooring, Head Beams are called Headers and they are used to support the overhead weight or load of an opening such as a window or door and Ceiling joists tie the outside walls together, support the ceiling materials for the room below, and secure the bottom ends of the rafters. 