Der schräge Anbau auf Kehlbohlen
This task model was challenging. Keeping track of the geometric lines to develop the valley sleeper rafter lines on the roof surface was confusing. However, I just needed to remember to draw perpendicular lines to the valley rafter in ground plan to the valley rafter on the roof surface plane to develop the correct valley sleeper plane lines. The witches cut is develop two different ways in the task model, by using two different elevation line heights.
Basic ground plan for the Valley Sleeper on oblique adjacent roof.
Drawing with the roof surface plane developed and some of the valley lines on the roof surface plane.
Zoomed in view of the valley lines, including the hidden bottom edge of the valley sleeper on the roof surface plane.
Drawing with the valley sleeper bird mouths lines developed.
Witches cut lines for the ground view of the valley sleeper rafters.
Witches cut lines for the valley sleeper rafters on the roof surface plane.
Method #two for developing the witches cut lines and the lines for the valley rafter bevel on the roof surface at the peak of the valley sleeper rafters.
Checking my drawing with the 3D valley sleeper rafters.
The new book on the ancient knowledge Roof Framing by Bernd Küppers