A list of the basic specification required when requesting roof trusses includes:

• Truss Span – specifies how long the bottom chord needs to be.
• Overhang Length – specifies the horizontal distance between the end of the bottom chord and the bottom edge of the top chord.
• Number of Trusses – specifies how many trusses are required. The uniform spacing of roof trusses (usually either 24 inches or 48 inches on center) makes this relatively easy to calculate.
• Design Load – specifies both the live and dead loads of the top and bottom chords, as well as wind and any other loads to which the trusses will be subjected.
• End Cut – specifies the plumb or square cut and any custom specifications
• Heel Height – specifies the vertical distance between the bottom of the bottom chord and the top of the top chord.
• Roof Slope – specifies the vertical rise in inches per each 12 inch horizontal run.
• Bearing Width – specifies the requirements for the truss bearing.
• Type of Truss – specifies the type of truss required.
• Overall Height – specifies the total vertical distance from highest point of top chord or peak to the bottom edge of the lowest bottom chord, not including the overhang.