Sunday, October 19, 2014

Fledermausgaube mit gerader Kehle

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

on page 94 , he describes the geometric technique to draw out an eyebrow dormer that rest on two canted valley rafters. I'm posting this drawing hoping that Bernd will comment on the questions I have on this drawing technique.

Bernd's answer

hello Sim
the angle between the hip line and the auxiliary line in the arc, is not necessarily 90 °. The important thing is, that the pitch break holds at least 3 tiles.
the legs of the upper triangle are hip lines and form the transition between curved and straight roof surface.
the third is the valley line in the front view
and the fourth is indeed the inner top edge of the inner valley rafter.

Bernd's suggestion
If you want, you can add the pages of the eyebrow dormer to your blog. This should explain the drawing method of the straight valley line.
I'm helping Bernd translate his book to readable English. Billy or Brad take a look at Bernd's current English translation and see if it make sense.  I think the biggest difference between his method and what I know on eyebrow dormer roof design, is the concept of designing the eyebrow dormer for tiles, instead of composition shingles.

Here's an image of the eyebrow dormer with the straight throat that Bernd Kuppers shared.

Here's a drawing by Bernd Brueck showing the hip and valley rafter of the eyebrow dormer and ribs with a straight throat.
Here's a link to the 3-D PDF file
Bernd Brueck Fledermausgaube


  1. so that makes sense because of the tiles if the pitch break is not at least 3 tiles wide i think they would have to cut tiles and the pitch break would not be "fair"

    1. So, I'm guessing the 3 tiles would equal about 18". I need to see or develop the roof surface of this eyebrow dormer for it to make sense.

  2. I think the 90º line is just to get something "normal " from the curve layout to project in the drawing

  3. having read it all ,it makes a lot of sense and is clear to me . the grammar may need a touch up but thats all the flat at the top which is developed as a 90º is clear as well . It is very clever

    1. Yea, the words plumb and circle needs to be changed.