How to Attach a Roof Truss to an Existing Structure

Lift the roof truss up to the roof by carrying it upside down by the main beam. Set the edge of the main beam onto the roof so that the beam is centered between the two opposite wall plates of the existing structure. Push the truss up from the side until it sits upright on the wall plates.

Stand on the ground beneath the peak of the truss where it sits on the roof edge while at least two people support the truss on the roof. Measure out from where you are standing roughly 3 feet in both directions. At each of these spots, measure 6 feet out from the wall and drive a wood stake into the ground so the bottom half is submerged.

Measure from each of these stakes up to the top of the roof truss. Cut wood boards down to this length. Secure the wood boards to the top of the roof truss with screws and to the wood stakes in the ground with screws to brace the roof truss in its spot.

Secure one end of the roof truss to the top wall plate on one side of the structure with bolts or metal framing anchors, depending upon the recommendation of the truss manufacturer. Move to the other side of the roof and secure the roof truss to the wall plate.

Move the second roof truss up to the roof in the same manner as the first. Place it on the top wall plates at the distance from the first truss that the manufacturer recommends. Cut four boards down to the distance between the first and second trusses and nail them to each truss to keep the second truss in place, while you secure the ends of the truss with bolts or anchors.

Install all of the roof trusses on the roof in this fashion, securing them together with wood boards to keep all the trusses in place. As you lay plywood or another type of roofing panel over the trusses to create the roof deck, remove the boards that hold the trusses together.