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
  
   
  

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SBE Builders
SBE Builders
5305 Laguna Ct.
Discovery Bay, California 94505
(925) 634-6022 • Fax: (925) 634-6022
Commercial & Residential Framing Contractor
American Carpenter and Builder
California Licensed General Building Contractor
CA LIC.#  546126


Roof Framing Geometry

  • Roof framing geometry is empirical-type knowledge.
  • Information gained by means of observation, experience, or experiment.
  • From ground Line 0: Z1, Z2, Z3 etc...
  • To Roof Axis 0: A1, A2, A3 etc...
  • To the bring back line 0 for scribing: B1, B2, B3 etc...

Roof Framing Geometry Blog

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We're a member of the Timber Framers Guild

Timber Framers Guild

American College of the Building Arts, carpentry and timber framing programs.

American College of the Building Arts

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