Design Load: - This is the Dead Load (weight of the framing) + Live Load (wind, snow, etc.).To determine the size of the rafters, using span tables, you need to know three things: When you are preparing to build a shed roof, you must first engineer the rafters - that is, know the species of wood you will use for the rafters, the nominal size of the rafters (2圆, 2x8, etc.), and the spacing of the rafters.
