Dachfläche --roof surface
Ausmittlung -- averaging -- design
Basiswissen Dachfläche Ausmittlung
Base Knowledge of Roof Surface Design/Geometry
The folding roof surface is needed for a basic understanding of the Shiftungen technique and the German book Basiswissen Dachausmittlung has some good examples of unfolding the roof surface.
Here are some drawings of the basic roof framing kernel unfolded.
Here are some drawings of the basic gable roof unfolded.
Drawing of unequal pitched hip roof with unequal overhang unfolded.