Major Roof Pitch 


Minor Roof Pitch 
 

Major Plan Angle atan(minor/major)
angle in plan on the steeper side.   working with the example of the 8/12, 10/12
8/10 =.8 , arc tan .8= 38.659 degrees = plan angle of 10/12 side

Minor Plan Angle atan(major/minor) angle in plan
of the shallowerpitched roof. 
 51.34 degrees = plan angle of 8/12 side 
Hip Run per Foot   8x10 divide 12= 6.666 =rise
8 divide 10 =.8 , arc tan .8 =38.65 degrees cos 1x 38.659 = 1.2806 1.2806 x
10 =12.806 = hip run for 810 runs 
Angle of Hip   6.666 divide 12.806 =.5205 arc tan .5205 =27.498 degrees
= angle of hip

Backing Angle Shallow Side of Hip   sine 27.498 = .4617= rise of backing angles
tan 51.34 degrees = 1.2499 .4617 divide 1.2499 = .369 arc tan .369 =20.27
degrees = saw backing bevel for 8/12 side of hip

Backing Angle Steep side of Hip   tan 38.659 = .799 , .4617 divide .799= .577
arc tan .577 =29.99 degrees = saw backing bevel of 10/12 side of hip. 