The Octagon Roof Framing 4 Butt Hip Rafter Method with Purlin Structural Ring calculator will calculate the rafter lengths for the Octagon 4 Butt Hip Rafter Method.
- #1 Main 2 Butt Hip Rafter Length
Cut 2 hip rafters at this length. These hip rafters will be installed first. The hip rafter head cut will have the Octagon Hip Rafter Slope Angle for the plumb cut angle and will not be beveled. - #2 Side 2 Butt Hip Rafter Length
Cut 2 hip rafters at this length. These hip rafters will be installed second, against the first two hip rafters. The hip rafter head cut will have the Octagon Hip Rafter Slope Angle for the plumb cut angle and will not be beveled. - #3 Mitered Hip Rafter Length
Cut 4 hip rafters at this length. Set the saw Blade Bevel Angle at 45.00°. The hip rafter head cut will have the Octagon Hip Rafter Slope Angle for the plumb cut angle and be beveled. - Mitered Hip Rafter Plumb Cut Mark Dimension
Measure along the side of the mitered hip rafter and use this dimension to layout the plumb cut line on the side of the hip rafter for the compound miter angle with the saw Blade Bevel Angle at 45.00°. - Compound Miter Angle for Hip Rafter Plumb Cut
This is the hip rafter side cut angle that is produced from the compound cut along the side of the hip rafter. You can use this angle to layout the top of the hip rafter when the saw blade is not long enough to cut the compound miter angle on the hip rafter. - #4 King Common Rafter Length To Purlin Structural Ring
Cut 8 king common rafters at this length. These king common rafters will have a square cut that butts into the purlin structural block. - Purlin Structural Ring Radius
The Purlin Structural Ring Radius is measured from the center point of the Octagon along the hip rafter run line. - Purlin King Common Rafter Run
The Purlin King Common Rafter Run is measured from the center point of the Octagon along the king common rafter run line. - Purlin Structural Ring Length
The Purlin Structural Ring Length is measured from the edge of Octagon hip rafters. - Purlin Structural Ring Miter Angle
The Purlin Structural Ring Miter Angle is marked on the side of the purlin block. - Purlin Structural Ring Bevel Angle
The Purlin Structural Ring Bevel Angle is the saw blade bevel angle used to cut the compound cut along the purlin block miter line. - Jack Rafter Lengths
The jack rafter lengths are calculated from the O.C. spacing from the king common rafter. The jack rafter lengths are to the long point of the jack rafter side cut.
Pages from the book Holy Grail of Roof Framing Trigonometry and Geometry
Online-- Equal Sided Octagon Geometric & Trigonometric Roof Framing Development
Online-- UnEqual Sided Octagon Geometric & Trigonometric Roof Framing Development
