## Saturday, February 9, 2013

### Dormer Shed Roof Rafter calculator

Rafter Tools

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

 Dormer Shed Roof Rafter Length Dormer Shed Roof Miter Angle (Rake Cut Angle) Dormer Shed Roof Sleeper Bevel Length Dormer Shed Roof Intercept Run ( Intersection of Dormer Roof and Main Roof) Main Roof Intercept Length (Useful for laying out Dormer Sleeper that is not Beveled) ```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``` ``` ``` `An example of the calculated results that you can email yourself in the Rafter Tools app ` Rafter Tools -- Dormer Shed Roof Calculations  Main Rafter Slope Angle  33.69007°  Main Rafter Pitch  8  in\12in  Main Rafter HAP  7 3/4''in  Main Roof Sheathing Material Thickness  1/2''in  Main Roof Rafter Material Depth  9 1/2''in  Main Roof Rafter Plumb Height  11 7/16''in  Main Run  28 1/4''in  Main Intercept Run  32 7/16''in  Dormer Rafter Slope Angle  14.03624°  Dormer Rafter Pitch  3  in\12in  Dormer Rafter HAP  8 7/16''in  Dormer Run  54 ''in  Dormer Roof Rafter Material Depth  9 1/2''in  Dormer Roof Rafter Plumb Height  9 13/16''in  Dormer Sleeper Material Thickness  1 1/2''in  Dormer & Main Roof Plate Line Difference  0  Dormer Rafter Length  84 3/4''in  Dormer Sleeper Bevel Length  4 7/16''in  Dormer Miter Cut Angle  19.65382°  Dormer Rafter Miter Cut Length  28 1/4''in  Dormer Intercept Run  82 1/4''in  Main Roof Slope Intercept Length  29 3/4''in  Dormer Rafter Length To Main Roof Sheathing Without Sleeper  89 1/4''in Main Rafter Slope Angle 33.69007° Main Rafter Pitch 8  in\12in Main Rafter HAP 7 3/4''in Main Roof Sheathing Material Thickness 1/2''in Main Roof Rafter Material Depth 9 1/2''in Main Roof Rafter Plumb Height 11 7/16''in Main Run 28 1/4''in Main Intercept Run 32 7/16''in Dormer Rafter Slope Angle 14.03624° Dormer Rafter Pitch 3  in\12in Dormer Rafter HAP 8 7/16''in Dormer Run 54 ''in Dormer Roof Rafter Material Depth 9 1/2''in Dormer Roof Rafter Plumb Height 9 13/16''in Dormer Sleeper Material Thickness 1 1/2''in Dormer & Main Roof Plate Line Difference 0 Dormer Rafter Length 84 3/4''in Dormer Sleeper Bevel Length 4 7/16''in Dormer Miter Cut Angle 19.65382° Dormer Rafter Miter Cut Length 28 1/4''in Dormer Intercept Run 82 1/4''in Main Roof Slope Intercept Length 29 3/4''in Dormer Rafter Length To Main Roof Sheathing Without Sleeper 89 1/4''in