Issue link: http://alpine.uberflip.com/i/684939
From the framing sections, shown above, we can see that the dormer Attic Girders carry a combination of both conventional framing and prefabricated trusses. The walls and trusses on each side of the girders have been omitted in these figures for clarity. The dormer width is 8'0" and there is a standard attic truss 2'0" from each girder on the opposite side of the dormer. Each girder attic truss supports one half of the dormer width, 4'0" of load to one face and one half of the distance to the adjacent truss, 1'0" of load to the opposite face. Adjusting the loads can be done in 5 steps: 1) Adjust the On Center spacing of the girder to increase the standard loads. 2) Extend the bottom chord room load to account for the additional accessible dormer floor. 3) Calculate and add the dead load from the supported knee walls. 4) Calculate and add the load resulting from the ceiling and overhangs of the trusses above the dormer. 5) Copy and modify Full Load case to create Unballanced Load Cases. Step 1 There are 2 methods to adjust On Center Spacing. Each method is acceptable and it is up to the designer determine which they prefer. Method One 1. Select the word Truss from the Main Menu at the top of the screen in iDesign.