Maximum span by grade
| Grade | Maximum span |
|---|---|
| Select Structural | 20′-9″ |
| No. 1 | 19′-1″ |
| No. 2 | 16′-6″ |
| No. 3 | 12′-10″ |
Span tables · Floor joists · 40 psf
40 psf live · L/360
2x12 Southern Pine floor joist span at 16″ o.c.
At 16″ o.c., a 2x12 Southern Pine #2 floor joist spans up to 16′-6″ under this table's load case. Select Structural and No. 1 reach further; No. 3 less. See the full grade breakdown below.
Southern Pine #2, 40 psf
What this span means
This is the maximum clear span the Table R502.3.1(2) permits for a 2x12 Southern Pine floor joist spaced 16″ o.c., carrying 40 psf of live load plus 10 psf dead load with a L/360 deflection limit. Spans are for repetitive members (three or more). Southern Pine values reflect the SPIB design values referenced by the IRC.
Actual allowable spans depend on your real loads, the lumber's moisture and exact grade stamp, bearing and connection details, and any point loads or openings. Treat this as a starting point, then confirm the member with your local code and a design professional.
Same member, other load case: Floor joists · 30 psf.
Source: International Residential Code (IRC), 2018 — Table R502.3.1(2) — Floor Joist Spans, 40 psf Live Load. Published by International Code Council.
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