Making roof trusses for your home is a job best left to the professionals. Modern roof trusses are engineered for specific environmental conditions and local building code requirements. Design engineers consider environmental conditions including the type of roofing material to be used, the overall home design, the wind speeds in the specific location, the snow loads (if any), and the additional weight of items like solar panels or HVAC equipment, among other factors. Designing and constructing roof trusses yourself is possible, but it is very difficult, time consuming, and not recommended.
Designing your own truss system requires an intimate knowledge of trigonometry and calculus, and familiarity with all of the variables associated with truss design. Companies specializing in truss design and manufacture have been around since the mid-1960’s.
Truss design companies use sophisticated computer modeling programs to make the necessary calculations. It is possible to obtain pre-designed truss specifications on the Internet, but they are very limited. You will only be able to build a home that will accommodate the truss system you choose online.
Planning departments require that all truss designs be approved by an engineer. This is expensive and drives up the cost for doing-it-yourselfers beyond what you would expect to pay a truss company for pre-fabricated trusses.
Construction grade pine 2 x 4 or 2 x 6 boards are used to manufacture trusses. Cutting the lumber is the most critical aspect of truss making. Truss companies use computer-operated saws to make the precision cuts necessary for identical truss fabrication.
Trusses are assembled on the factory floor. This is done by laying out the individual pieces of lumber, which make one truss, on the floor. The truss layout is double checked by a supervisor before the individual pieces are fastened together.
Fastening truss boards together has evolved over the years. Initially the boards were connected by placing cut pieces of 1/2-inch plywood on both sides of the truss boards at the intended joint. Holes were drilled, nuts and bolts were attached, and the truss joint was created. This method is heavy and time consuming. Nail plates are used today. Nail plates are made of heavy gauge, galvanized sheet steel. Nail plates are pressed into both sides of a truss joint, overlapping both pieces of wood that are being joined.
Completed trusses are very flimsy if they are not standing upright in their design position. Care must be taken when handling trusses. Completed trusses are shipped to the jobsite on a crane truck, and hoisted into position where they are installed.
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