Unequal Pitched Gable Rafters with Unequal Plate Heights

The Unequal Pitched Gable Rafters is a very useful tool in roof framing. You can use it as a simple equal pitched gable rafter calculator or use it to calculate unequal pitched gable roofs with unequal plate heights. The Unequal Pitched Gable Rafters calculator for equal or unequal pitched gable roofs will print out the dimensions / lengths for the gable rafters.


Input variables

  1. Main Roof Pitch or Angle
  2. Adjacent Roof Pitch or Angle
  3. Input Length
    1. Building Span
    2. Main Pitch Rafter Run
    3. Adjacent Pitch Rafter Run
  4. Overhang Run
  5. Ridge Width
  6. Main Rafter Material Depth
  7. Adjacent Rafter Material Depth
  8. Main Rafter Seatcut Length
  9. Adjacent Rafter Seatcut Length

Main Roof Pitch or Angle
Select the input type from the input menu, Imperial/English Inch base 12 —— default, enter roof pitches from 1—24 like 8 for an 8:12 pitched roof, Metric 300mm base, enter millimeters like 200 for a 33.69007° roof pitch angle, Decimal Inch base 10 —— enter base 10 decimal numbers like 5.7735 for a 30° roof pitch angle, Degrees input —— use any roof angle in degrees like 33.69007°

Adjacent Roof Pitch or Angle
Select the input type from the input menu, Imperial/English Inch base 12 —— default, enter roof pitches from 1—24 like 8 for an 8:12 pitched roof, Metric 300mm base, enter millimeters like 200 for a 33.69007° roof pitch angle, Decimal Inch base 10 —— enter base 10 decimal numbers like 5.7735 for a 30° roof pitch angle, Degrees input —— use any roof angle in degrees like 33.69007°

    Input Menu Mode
  1. Imperial/English Inch base 12 —— default.. use American standard pitches over 12.
  2. Metric 300mm base —— 300mm is 11.81102 inches, similar usage to the American framing squares printed in inches.
  3. Decimal Inch base 10 —— use this option when working with tangents or using the Chappell Master Framing Square multiply the tangent of the angle by 10
  4. Degrees

Input Length Type
This menu option allows you to select different parts of the gable roof for calculating the dimensions of the roof.

    Input Length .. Select one of the following
  1. Building Span
  2. Main Pitch Rafter Run
  3. Adjacent Pitch Rafter Run

Overhang Run
This menu option allows you to set the main pitch rafter overhang run. The adjacent pitch rafter overhang run will use the same overhang run to calculate the rafter overhang length.

Main Rafter Material Depth , Adjacent Material Depth
This menu option allows you to set the depth of the rafters that is used to calculate:

Seat Cut Level Cut Length
This menu option allows you to set the length of the seatcuts of the main and adjacent rafter pitches that is used to calculate:

Ridge Width
This menu option allows you to set the width of the roof ridge. It is used to calculate:

Calculated Results for the Unequal Pitched Gable Rafters. 

  1. Main Roof Slope Angle
  2. Adjacent Roof Slope Angle
  3. Main Pitch
  4. Adjacent Pitch
  5. Main Rafter Run
  6. Main Rafter Theoretical Length
  7. Main Rafter Ridge Reduction Run
  8. Main Rafter Length To Ridge
  9. Main Rafter Seatcut Length
  10. Main Rafter Overhang Length
  11. Adjacent Rafter Run
  12. Adjacent Rafter Theoretical Length
  13. Adjacent Rafter Ridge Reduction Run
  14. Adjacent Rafter Length To Ridge
  15. Adjacent Rafter Seatcut Length
  16. Adjacent Rafter Overhang Length
  17. Adjacent PL Height Above Main PL
  18. Main Rafter Theoretical Rise
  19. Rise To Top Of Ridge From Main Plate Line
  20. Plate Height Adjusted
  21. Building Span
  22. Building Span Adjusted
  23. Main Rafter HAP
  24. Main Rafter Plumb Height
  25. Adjacent Rafter HAP
  26. Adjacent Rafter Plumb Height