Rafters for a 20-Foot Span
A 20-foot span gable roof at 6/12 pitch (40 ft long) needs about 62 rafters roughly 12.3 ft long, plus a 40 ft ridge board. Adjust span, length, and pitch below.
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Want the full guide — tools, step-by-step, common mistakes and FAQ? See the Roof Framing Calculator.