Roof Load Distribution

For dead loads you are correct.

Roof load distribution. You will be designing with two sets of loads. However in my practice i typically use the horizontal run of the roof for both types of load. Technically you should use the actual rafter length when adding up the weight of roofing materials. The dead load of a typical asphalt shingled wood framed roof is about 15 pounds per square foot.

Roof uniform load distribution these examples use an assumed load of 40 psf. To do this i use conservative too heavy dead loads and full snow loads regardless of pitch. The live load appropriate to your locale is specified by your building official. Live loads and total loads which are dead load live load.

A clay tiled roof may have a dead load. Remember these loads are distributed uniformly over the entire surface of the roof. Here each square foot of roof system delivers 50 pounds of live load and 15 pounds of dead load 65 psf total to the structural support system. A fixed node will provide support in both directions down the length of the roof truss members often called the x and y directions.

In order for a roof truss load to be stable you need to assign two of your nodes on each truss to be support nodes.