I would appreciate some help in understanding roof design. The object, to correctly dimension principal or common rafters.

Can the equations for horizontal beam loading be used, working with the sloping loads projected onto the horizontal plane? I find no examples for this in Benson's books nor in the TFG Workbooks.

Further than this, I would like to go into the whole snow/wind loading formulae. I have looked at the American Wood Council's material but this uses span tables for 2" timbers only. Can someone reccomend tutorial material for this subject?

Thanks