Saturday, February 9, 2013

Pitch Break Shed Roof Rafter Calculator

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


  1.  Pitch Break Shed Roof Rafter Length 
  2. Pitch Break Shed Roof Miter Angle (Rake Cut Angle) 
  3. Total Pitch Break Run ( Intersection of Shed Roof and Main Roof) 
  4. Main Roof Intercept Length 
  5. Main Roof Run To Intersection of Main Roof And Shed Roof


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

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

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




3 comments:

  1. First time I commented in a blog! I really enjoy it. You have an awesome post. Please do more articles like this. I'm gonna come back surely. God bless.

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  2. I'm building my house and I have run into a problem with the roof. The house is a rectangle with a gable(6:12), I have a perp. gable(8:12) in the middle of the house and on the back I have a shed roof that covers the back porch. What would be the best way to frame this up? Thank you!!

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