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Some interesting and funny comments from the magazine Carpentry & Building  published in 1890. Fig. 5 shows  this  method  of  getting  the hip rafter backing on  both  sides  of  an  irregular  hip rafter.   It has been already explained, by getting the distance in plan. This letter would have been unnecessary and not deprived me of my afternoon nap, if the reader would have followed the laws of geometry. Fig 5 Irregular Hip Roof Fig 6 Equal Pitched Hip Roof This is funny. The drawing is correct and is the most simple to follow and the best for general use to determine the hip rafter backing angles. ______________________________________________________________ Which Rule for Backing Hip Rafters is the Best? From HAH Avoca Wis  Will you please inform me which of the various rules you have published for backing hip rafters you consider the most simple to follow and the best for general use.  I have examined the correspondence containing these rules and find that one writer pronounc

English translation for Witches Cut 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 Does this make sense? ______________________________________________ Witches cut: Hexenschnitt: Example 3: The true witches cut using the basic method On unequal pitched roofs the hip- or valley rafter is inclined less than the rafters or jack rafters and it gets the so-called witches cut eave cut (tail cut). This witches cut only occurs on tail cuts that are not plumb cuts at the eave line. If the unequal sloped main and adjacent roof rafters have a right angle rafter tail cut (square tail fascia) and this cut direction is transmitted to the hip rafters, one speaks of a true witches cut. To illustrate a cross-sectional direction it requires two points at different heights. The eave line as height 0 (zero) offers itself

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. Dachausmittlung Roof Design from Intersecting Roof Surfaces Optional Roof Design: Here's the roof surface design for the PIA equal overh

We need an German to English translation for the folding roof surface. From Bernd Kuppers book: German Erweiterung Einführung ins Flächenklappung English Extension Introduction to Surface Folding Plane Joinery? Maybe the "Joinery Plane"? Yes, it's the plane where you develop the geometrical lines for the rafter joinery. Roof Surface Plane Dachfläche Dach = Roof fläche = Surface Ebene = Plane ??? flächenklappung flächen = Surface klappung = Folding

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 t

Das neue Buch vom alten Wissen der Schiftung The new book on the ancient knowledge Schiftung The new book on the ancient knowledge Compound Joinery The new book on the ancient knowledge Roof Framing The new book on the ancient knowledge Roof Framing Geometry by  Bernd Küppers More images and information on the book can be found at this link. Shiftung Image from Bernd's Facebook page on Shiftung. Verkanteter Kehlsparren in German = Tilted-Canted- Rotated Valley Rafter Looking at page 52 in his book I decided it was time to study the valley rafters rotated into the roof surface plane. The same geometric techniques used for hip rafters rotated into the roof surface plane   can also be used for the valley rafters rotated into the roof surface plane.  Some of the geometry used for valley rafters rotated into the roof surface plane is  empirical-type knowledge.  Information gained by means of observation, experience, or experiment.  From this empirical knowledge we know the valley jack r

Bernd Brück   sent me a couple more drawings. These represent the   Obhölzer, rafter seat calculations. Lotrechtes Obholz = HAP = Height Above Plate Rechtwinkliges Obholz = What we would call the structural engineering D4 calculation.  Sparrenhöhe = depth of rafter Lotrechte Kerventiefe = Height Below Plate Lotrechte Sparrenhöhe = Rafter Plumb Height Dachneigung =  Rafter slope Angle The standard American rafter seat calculations starts with the length of the seat cut or HAP of the rafter. The Germans and Europeans use the  Rechtwinkliges Obholz    method. A dimension parallel to the top of the rafter.

Dachneigung (Grad): = Roof Slope Angle Gratsparrenneigung (Grad)= Hip Rafter Slope Angle (R1) Gebäudegrundwinkel innen (Grad): = Eave Angle Gratsparrengrundwinkel (Grad)=  Plan Angle Abgratungswinkel (Grad)= Hip Rafter Backing Angle Anreißwinkel (Grad)= Hip Rafter Side Cut Angle Schifter Anreißwinkel (Grad)= Jack Rafter Side Cut Angle Hexenschnitt (Grad)= Witches Cut = ( 90° - R2) Backenschmiege = Back Bevel Dachausmittlung = Roof Design Hauptdach = Main Roof = HD Kerve = Birds Mouth = Seat Cut Pfetten = Purlin Traufe = Eave Stirnbrett = Fascia Traufabschnittswinkel (Grad)=  For Hip Rafter Angle Q3 = Projected Fascia Pitch Angle + Hip Pitch Angle or 90° - (R1+R2) = 90° - ( Hip Rafter Slope Angle + Hip Rafter Purlin Housing Angle) Hip Rafter Miter Angle = 90° - (Projected Fascia Pitch Angle + Hip Pitch Angle) Hip Rafter Miter Angle = 90° - (46.69° + 25.24°) = 18.07° Verstichmass =  Hip Rafter Plumb Line Shift dimension Abgratung = hip rafter backing Auskehlung = valley rafter backing Be

Math for equal pitched roofs for  Hip Rafter Plumb Line Shift  (1/2 of hip rafter width) * tan( 90° - plan angle) =  Hip Rafter Plumb Line Shift  dimension (0.75) * tan( 90° - 45) = 0.75 Hip Rafter Shift Dimension in Decimal Inches  Hip Rafter Width 1.5 1.75 2.5 3 3.125 3.5 5.125 5.5 Rectangle - 90° 0.75 0.875 1.25 1.5 1.5625 1.75 2.5625 2.75 Pentagon - 108° 0.54491 0.63572 0.90818 1.08981 1.13522 1.27145 1.86177 1.99799 Hexagon - 120° 0.43301 0.50518 0.72169 0.86603 0.90211 1.01036 1.47946 1.58771 Octagon - 135° 0.31066 0.36244 0.51777 0.62132 0.64721 0.72487 1.06142 1.13909 Hip Rafter Shift Dimension in Fractions of Inches Hip Rafter Width 1 1/2 1 3/4 2 1/2 3 3 1/8 3 1/2 5 1/8 5 1/2 Rectangle - 90° 3/4 7/8 1 1/4 1 1/2 1 9/16 1 3/4 2 9/16 2 3/4 Pentagon - 108° 9/16 5/8 15/16 1 1/16 1 1/8 1 1/4 1 7/8 2 Hexagon - 120° 7/16 1/2 3/4 7/8 7/8 1 1 1/2 1 9/16 Octagon - 135° 5/16 3/8 1/2 5/8 5/8 3/4 1 1/16 1 1/8 Hip Rafter Shift Dimension in Millimeters (mm) Hip Rafter Wi

In complex roof framing there are 7 main roof framing angles. Hip Rafter Backing Angle Valley Sleeper Bevel Angle Plain Titl (DP) Main Plan Angle Adjacent Plan Angle  Main Profile Rafter Slope Angle Adjacent Profile Rafter Slope Angle In this article I will discuss the hip rafter backing angle and the valley sleeper bevel angle. These two angles determine the miter angle and and saw blade bevel angles for jack rafters and purlin rafters that are plumb to the earth and for jack rafters and purlin rafters that are skewed from the eave line. A thorough knowledge of these two angles is critical in complex roof framing using geometry or trigonometry. The hip rafter edge bevel was avoided in the 12th century on some roof structures by rotating the hip rafter into the roof surface plane. However, by avoiding the hip rafter edge bevel, the carpenters-builders had to have a knowledge of the Valley Sleeper Bevel Angle. They didn't call it the Valley Sleeper Bevel Angle, but it's the same