Check with the National Design Specification for Wood Construction and your local building code to determine the pitch of the roof and the timber size needed to comply with the code in your area.
Measure and cut the timber for the top chords and bottom chord for the triangle truss. The top chord is the two pieces of the truss that form the point of the roof and the bottom chord is the ceiling piece of the truss. The measurements and angles will vary depending on your particular roof design.
Lay the pieces together on a flat surface with the joints together. Tap the galvanized metal plates into the wood holding the joints together. Use 1 1/2-inch screws o reinforce the metal plates.
Measure to determine the length and angles needed for the web studs. The web studs strengthen the trusses acting a bracing within the structure. Two of the studs will meet at the peak of the truss and extend to the bottom chord forming an A-like shape in the center of the truss and two will extend from the center web studs back to the top chord. Cut the web studs and lay the web studs in place. The web studs should form a "W" shape within the truss.
Fasten the web studs to the top and bottom chords, using the metal plates and screws. Use the first rafter as a template for the rest of the trusses needed to complete the roof structure.