How to Frame a Roof Truss
A roof truss is a triangular shaped piece of wood framing that is designed to bear the weight of the roof, stabilize walls, and provide overall reinforcement for the structure. There are a variety of ways to frame a roof, but using roof trusses will shorten the framing time, save on materials (i.e. lumbar) used in framing a roof, and generally provides superior support to the roof structure. While roof trusses can be pre-fabricated and ordered to the specifications needed for you structure or addition, building your own roof trusses will save money on the job, and are not difficult or time consuming to build. You will need a few specific tools, and good measuring equipments such as angles and squares.
Step 1 - Measure for Trusses
Start by measuring the pitch, needed, width and height needed for the trusses. This will determine both the style as well as the size of the truss that is needed. Cut all lumber to the needed lengths. Trusses are basically a triangle, and there are generally four pieces of lumbar to each truss: the two sides that are joined together at angles, a brace beam that creates the bottom of the triangle, and a support piece that bisects the triangle from the peak to the support beam. If the truss is large, or if it will be bearing a significant amount of weight, two additional support beams are generally added at forty-five degree angles to the support beam and the bisecting support.
Step 2 - Cut Lumber
Cut all of your lumber to the appropriate lengths and angles. Remember the golden rule of carpentry: measure twice and cut once. You will assemble each truss laying down on the ground, generally outside, then lift it into place. Mark all of your cuts before you take the saw to them. This will help you to visualize the truss as it comes together, and help you to identify any pieces that have been inaccurately measured.
Step 3 - Attach Gussets
Attach gussets at the top angle, and on each side of the support beam at the bottom of the triangle. Attach gussets also to each joint for the support beam or beams. Secure each gusset with the nails. Gussets should be placed on either side of the truss, so you will have to, once all the gussets are done on one side, flip the truss over and attach them in the same places on the other side.
Step 4 - Place Frame
You will place each truss on the wall framing at intervals of every two feet. Any time you are working on a roof, you need to be extra careful. Have a couple of extra people to lift and hold the truss in place and hold it while it is secured. You will want to secure each of the trusses, but check for plumb before you secure them.