My way in doing these elements is using Roof by Extrusion and walls as helpers for beams and purlins :
Constantin Stroescu
pasterski.k
The method Constantin shows is the best way, here is a screencast i done last month for the same issue.
https://screencast.autodesk.com/Main/Details/f253c591-bc63-4e6b-a2d4-da20667fc7b5
And as Constantin said, use a "Roof by Extrusion" for the curved roof, drawn in an Elevation/section
Hope this helsp