Saturday, October 25, 2014

Layover Valley Rafter Hexenschnitt #1

While studying the: The Layover Valley Sleeper with Witch Cut
Die Kehlbohle mit Hexenschnitt

In the book
Das neue Buch vom alten Wissen der Schiftung
The new book on the ancient knowledge Schiftung
The new book on the ancient knowledge Roof Framing
The new book on the ancient knowledge Roof Framing Geometry
by Bernd Küppers

I realized I need to backtrack and draw out the roof surface averaging lines used to determine the ground plan roof framing geometry, the intersection of lines of the individual roof surfaces. I could have cheated and used my RafterTools Calculator app for the plan angles of the three different roof slopes on the task model, but then it would have defeated the purpose of studying the Shiftung geometric method for the witches cut of the layover valley sleeper. Just a refresher in developing the plan angles using geometry only.

Roof Design
Intersecting Roof Surfaces

Optional Roof Design:
Here's the roof surface design for the PIA equal overhang. 

Here's the plate heights for the PIA equal overhang.


  1. why not make the eave line equal from the plate ? this is what would happen in real life and what MANY "carpenters " fail to understand . I also think where you show the 30º slope could be confusing as that is where the roof surface should be drawn and folded

    1. I made the overhang unequal for equal height plate lines for the task model. Just easier to draw in 3D with unequal height plates. It would probably only be equal on the East coast. We always make or overhang unequal here on the west coast, because we don't have soffits and this is square tail fascia. The bird blocks would look better on unequal overhang.

      Yeah, the 30° profile should have been drawn on the other side for clarity.
      Added a new drawing for the 30° profile on the other side.

    2. I don't mean to be a PIA
      Yes we have to make equal overhangs with different pitches all the time and some time even the soffits are following the slopes and cathederal ceilings as well . So best to understand how to do it all

    3. Added a drawing of the PIA equal overhang roof surface design. But you'll have to frame it.:)

  2. Sim I could give you the contact of a young German who has good english and he could help you with some of the translation