Residential trusses are professionally designed with state of the art computer programs. The components are precision cut and assembled in a factory controlled environment. Each truss bears the Truss Plate Institute (TPI) stamp for quality assurance. Truss capacity is listed by pounds per square foot based on the following load rating criteria: Top chord live load (snow and other temporary loads), top chord dead load (roofing materials, weight of the truss itself & other permanent items attached to the roof), bottom chord live load (storage) and bottom chord dead load (insulation, ceiling materials, ceiling fans, etc.). Trusses save time and materials compared to conventional hand framing.