Joist Span Calculator

Look up an approximate allowable floor-joist span by size and spacing for #2 SPF. A rough guide — design from the adopted code span tables.

Floor Joist (#2 SPF)

Joist Size

Spacing

Allowable Span

⚠ Pending verification — allowable spans are safety-critical and are being reconciled against the AWC/NDS span tables (by species, grade, load, and deflection) before publishing a number.

Size joists from the adopted code span tables (AWC / IRC R502.3.1) or an engineer.

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