SBE Builders

Strong Built Establishments Builders

SBE Builders is a commercial and residential framing contractor located in Discovery Bay California. Dedicated to the art of Carpentery & Roof Framing. We are the professionals for the future of the craft of carpentry.

This Dormer Shed Roof calculator will return roof framing trigonometry & geometry details for:

  1. Dormer Shed Roof Rafter Length
  2. Dormer Shed Roof Miter Angle (Rake Cut Angle)
  3. Dormer Shed Roof Sleeper Bevel Length
  4. Dormer Shed Roof Intercept Run ( Intersection of Dormer Roof and Main Roof)
  5. Main Roof Intercept Length (Usefull for laying out Dormer Sleeper that is not Beveled)

Dormer Shed Roof Rafter Calculator

Dormer Shed Roof Details
    Main Roof Pitch
    Dormer Roof Pitch
    Main Roof Rafter HAP
    Dormer Roof Rafter HAP
    Main Roof Rafter Material Depth
    Dormer Roof Rafter Material Depth
    Dormer Sleeper Material Thickness
    Main Roof Sheathing Material Thickness
    Plate Line Height Difference entered in Inches
Enter a negitive number if the Dormer PL is below the Main Pl
    Dormer Run
Entered in Inches

show results in feet & inches


results are show below in the IFrame window

  
Using the Law of Sines 
c = ( a × sin( C ) ) ÷ sin( A)

c = Dormer Roof Rafter Length
C1 = 90° - Dormer Roof Pitch Angle
C2 = 90° - (Main Roof Pitch Angle - Dormer Roof Pitch Angle)
C = 90° - Dormer Roof Pitch Angle + (90° - (Main Roof Pitch Angle - Dormer Roof Pitch Angle))
C = C1 + C2
A = Main Roof Pitch Angle - Dormer Roof Pitch Angle  
a = Dormer Roof Run

Dormer Roof Rafter Length = (Dormer Roof Run × sin(90° - Dormer Roof Pitch Angle + (90° - (Main Roof Pitch Angle - Dormer Roof Pitch Angle)))) ÷ sin(Main Roof Pitch Angle - Dormer Roof Pitch Angle )
or
Dormer Roof Rafter Length = (Dormer Roof Run × sin(C)) ÷ sin(A)
or
 
Dormer Altitude = sin(Dormer Roof Pitch Angle) ×  Dormer Run
Dormer Altitude Run = Dormer Altitude ÷ tan(Dormer Roof Pitch Angle)
Dormer Miter Cut Angle =  Main Roof Pitch Angle - Dormer Roof  Pitch Angle
Main Altitude Run = Dormer Altitude ÷ tan(Dormer Miter Cut Angle)
Dormer Rafter Length = Dormer Altitude Run + Main Altitude Run
Main Intercept Run = (Dormer Rafter Length  × cos( Dormer Roof Pitch Angle)) - Dormer Run
  
   
  

  
  
SBE Builders
SBE Builders


Holy Grail of Roof Framing Geometry & Trigonometry

Book I & Book II. These roof framing books were written to make complex roof framing simple..

The Art of the Line for Carpentry

The book includes step by step instructions on developing stereotomic drawings on Art du Trait de Charpente, Trestles, Tréteau à devers, Canted Trestles, Louis Mozerolles' Joiners Table, Sawhorses, and the Saint Andrews' Cross, twisted crosses. You'll also find theories on hip rafter shift-offset, standard roof framing kernel trait drawings, German Schiften DP-Shadow Line techniques, folding net roof surface and net plane geometric development, when hip rafters collide, the Warlock Cut, and developing upper and lower claws on rafters using Axioms.

HG IV Circular Work in Carpentry

The book includes step-by-step instructions on developing stereotomic double curvature drawings for circular work in carpentry. Some of the techniques presented in this book are thousands of years in the making. As carpenters, we shouldn't have to re-invent the wheel each time we are faced with new challenges. There is a likely hood that someone, that came before us, has already refined a technique that we can use today. The tools might have changed, but the piece of wood that it is twisting and turning remains the same piece of wood.

Rafter Tools+ for iPhone

Rafter Tools+ is a rafter calculator for complex roof framing angles that other roof framing calculators don't offer.

RafterTools+

Stair Tangent for iPhone

This iPhone app is for rough frame carpenters that don't build stairs everyday, but could use an stair app calculator to check their stair building calculations.
Build a set of stairs that you are gonna be proud of.
With Stair Tangent you can elimenate cumulative math errors when building - constructing stairs.

Stair Tangent
stairtangent.com

Crown Molding Tools
crownmoldingtools.com

Crown Molding Tools  

Roof Framing Geometry Blog

Website Usage Legal Policy