Maximum span by grade
| Grade | Maximum span |
|---|---|
| Select Structural | 13′-10″ |
| No. 1 | 13′-6″ |
| No. 2 | 13′-6″ |
| No. 3 | 10′-8″ |
Span tables · Floor joists · 30 psf
30 psf live · L/360
2x8 Spruce-Pine-Fir floor joist span at 16″ o.c.
At 16″ o.c., a 2x8 Spruce-Pine-Fir #2 floor joist spans up to 13′-6″ under this table's load case. Select Structural and No. 1 reach further; No. 3 less. See the full grade breakdown below.
Spruce-Pine-Fir #2, 30 psf
What this span means
This is the maximum clear span the Table R502.3.1(1) permits for a 2x8 Spruce-Pine-Fir floor joist spaced 16″ o.c., carrying 30 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 · 40 psf.
Source: International Residential Code (IRC), 2018 — Table R502.3.1(1) — Floor Joist Spans, 30 psf Live Load. Published by International Code Council.
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