Roof trusses are generated in the space between the roof planes and the ceiling planes below. When a vaulted ceiling is created scissor trusses are used.
Certain conditions must be met before an attic truss can be built. These include: the structure should be sufficiently wide to allow for a loft and attic spaces, the loft area must be on a living floor and have Attic rooms on both sides separated by Knee Walls, a flat ceiling in the loft area and a floor below, steep enough roof pitch to provide appropriate ceiling height for the loft area. In addition, the roof should bear on the walls of the floor below the loft area and form continuous planes from ridge to baselines. Once all of these conditions are met, a roof truss is ready to be designated as an attic truss.
To create an energy heel, in the Build Roof dialog check Trusses (no Birdsmouth), uncheck Automatic Birdsmouth Cut, specify the desired energy heel height as a positive Raise Off Plate value, automatically generate or manually draw the roof planes, then draw and position the first truss. Open this truss’s specification dialog, check Energy Heel and Force Truss Rebuild, then click OK and use the Multiple Copy edit tool to replicate the truss as needed.
Home Designer Pro gives you the ability to place roof trusses manually.