pitch and the angle decreases as the pitch increases. The side cut of the hip/valley rafter = (Tangent)(12) = side cut in inches. The side cuts in the rafter table are all in a base 12. The arc tan can be determined from any given pitch. Most power tools and angle measuring devices use 90° as 0° in construction. The complementary angles of the arc tan are used with tools like the speed square. Side cut of jack rafters The side cut is located at the intersection of the side cut of jack rafters row and the pitch column on the Steel square. There is a row for the difference in length of jacks, 16 and 24 inch centers on the blade. The tangents are directly proportional for both centers. The tangent is in a base 12. The tangent x 12 = side cut of jack rafters. This corresponds to the side cut on the Steel square. The complementary angles of the arc tan are used on most angle measuring devices in construction. The tangent of hip, valley, and jack rafters are less than 1.00 in all pitches above 0°. An eighteen pitch has a side cut angle of 29.07° and a two pitch has a side cut angle of 44.56° for jack rafters. This is a variation of 15.5° between pitches. Side cut angles versus pitch This is a reference table for side cuts versus pitch. (only valid for 90 degrees eave angle) : Pitch expressed in rise units / run units Pitch 18/12 ==> 60,86 deg Pitch 17/12 ==> 60,10 deg Pitch 16/12 ==> 59,07 deg Pitch 15/12 ==> 57,99 deg Pitch 14/12 ==> 56,94 deg Pitch 13/12 ==> 55,88 deg Pitch 12/12 ==> 54,69 deg Pitch 11/12 ==> 53,49 deg Pitch 10/12 ==> 52,54 deg Pitch 9/12 ==> 51,25 deg Pitch 8/12 ==> 50,19 deg Pitch 7/12 ==> 49,17 deg Pitch 6/12 ==> 48,15 deg Pitch 5/12 ==> 47,33 deg Pitch 4/12 ==> 46,54 deg Pitch 3/12 ==> 45,90 deg Pitch 2/12 ==> 45,22 deg Pitch 1/12 ==> 45,10 deg Pitch 0/12 ==> 45,00 deg Plumb cut of jack and common rafters The plumb cut for jack and common rafters are the same angles. The level cut or seat cut is the complementary angle of the plumb cut. The notch formed at the intersection of the level and plumb cut Is commonly referred to as the bird's