This document provides instructions and formulas for constructing an octagonal roof. It explains that the angle between crown ends and hips is always 22.5 degrees, regardless of the roof size. It then provides formulas to calculate the length of the octagonal ends based on this constant angle: half the end equals half the span multiplied by 0.414, and the full end equals half the span multiplied by 0.828. The document also addresses calculating lengths for the major and minor crown end rafters, noting they are calculated similarly to a normal hip roof.