Occassionally buyers of my shed plans complain that when they are making shed trusses and they don't fit the way they should, they complain that the angles and cut lengths shown on their plans are wrong. here's just a recent complaint i received not to long ago for the truss construction contained in my 12x16 gale shed plans:. How to build a shed: building & installing roof rafters. how to build a shed roof step by step. sorry now that we've built all the walls are not gonna take a step back for a 0:07build the walls i. The fourth step in the how to build a shed series this tutorial teaches you the necessary steps to building roof rafters. from cutting the rafter parts out to building a jig and assembling the rafters! a rafter is one side of the rafter assembly. the rafter assembly is made by using an o.s.b. gusset.