Rafters for a 40-Foot Span

A 40-foot span gable roof at 6/12 pitch (40 ft long) needs about 62 rafters roughly 23.5 ft long, plus a 40 ft ridge board. Adjust span, length, and pitch below.

Rafters

62 rafters

Rafters

6231 per side · 16" o.c.

Rafter length

23.5 ft6/12 pitch · incl. 12" overhang

Cut from

2×8 × 24 ftextra length for plumb & bird’s-mouth cuts

Ridge board

40 ft2×10 along the peak

Material cost (est.)

$2,181rafters + ridge + ties

Planning estimate. Adjust allowances and sample prices for your supplier; tax, delivery, and labor are not included.

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Rafters for a 40-Foot Span

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