Span lookup
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Maximum allowable span
12′-9″
A 2x8 Douglas Fir-Larch no. 2 floor joist at 16″ o.c. may span up to 12′-9″ under this table's load case (40 psf live, 10 psf dead, L/360).
Source: International Residential Code (IRC), 2018 — Table R502.3.1(2) — Floor Joist Spans, 40 psf Live Load (International Code Council).