Some different types of floor trusses include hybrid trusses, wood trusses, Pratt trusses and parallel trusses. Hybrid and wood trusses differ in the materials used to make them, whereas Pratt and parallel trusses differ in the manner in which the boards are arranged during trussing.
Hybrid trusses are primarily made of wood, with steel incorporated at the joints to make the structure more stable, strong and flexible. Such trusses are normally used in multi-storey and commercial constructions.
Wood trusses are made entirely of wood. Flooring made of wood trusses is capable of withstanding large weights and stiff flooring materials such as ceramic tiles. Wood trusses are less expensive than hybrid ones and are commonly used in residential constructions.
Both hybrid and wood trusses can incorporate parallel or Pratt trussing styles. In the Pratt trussing style, beams are positioned parallel to one another, and other boards are placed at an angle, or diagonally in one or two directions between them. Sometimes, boards are also laid perpendicular to the parallel ones. Such an arrangement makes the truss strong and stable. The truss is finished by nailing plywood over it.
In the parallel trussing style, straight boards are used to connect the parallel beams in place of diagonal ones. Although the support provided by this trussing style is more than that offered by a beam floor, it is less than that offered by Pratt trussing style. Also, parallel trusses are less stable and less expensive than the Pratt ones.