Obviously, there are numerous specifications & instructions when setting rafters/trusses depending on the design of your roof line. Always refer to your house plans for rafter/truss locations & specs. Always have enough qualified installers to set rafters; 3 people up and 3 people down is a good rule of thumb to follow. With larger rafter systems, a crane will be needed.
For the sake of simplicity, this “How To” article outlines procedures for setting a no hip common gable truss/rafter system on a ranch style house.
1) Mark walls for perimeter point with rafter widths on 2’ centers.
2) Nail bracing on the gable ends before setting end gable rafters.
3) Set both gable end rafters flush with walls and in center of the wall; level each gable end; install additional bracing to gable end rafters to gain stability.
4) String a line from one gable to the other.
5) Set rafter/truss and center the top of the rafter with the line.
6) Nail 2’x4’ bracing on the rafters on 2’ centers. Note: marking your brace on 2’ centers will speed installation.
7) Toe nail the rafter to the exterior wall at your 2’ center mark.
Roof trusses are much less labor intensive than stick built rafters and lessen job-site debris. The trusses are made to order and are delivered to the job site ready to install which speeds up the building process with fewer laborers.