Hip / Valley / Jack Rafter Schedule
Common-rafter and hip multipliers, jack-rafter shortening per OC, irregular-hip second pitch handling. Framing-square method.
Formula and source
Common-rafter run multiplier m = sqrt(P² + 144) / 12 (P = pitch, rise per 12 in run). Hip / valley multiplier m_hip = sqrt(P² + 288) / 12 (square 12 × 12 diagonal = 16.97). Jack-rafter shortening per OC: dx_oc = oc × m_common; jack length at distance n × dx_oc = (run − n × dx_oc) × m_common.
Carpentry framing-square method by name. Public layout taught in any framing-square reference (Steel Square Pocket Book, Audel's Carpenters and Builders Library) by name.
Audience
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