Maximum span by grade
| Grade | Maximum span |
|---|---|
| Select Structural | 17′-5″ |
| No. 1 | 15′-1″ |
| No. 2 | 15′-1″ |
| No. 3 | — |
Span tables · Rafters · 30 psf snow
30 psf live · L/180
2x8 Spruce-Pine-Fir rafter span at 16″ o.c.
At 16″ o.c., a 2x8 Spruce-Pine-Fir #2 rafter spans up to 15′-1″ 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 R802.4.1(3) permits for a 2x8 Spruce-Pine-Fir rafter spaced 16″ o.c., carrying 30 psf of live load plus 10 psf dead load with a L/180 deflection limit. Rafter spans are the horizontal projection. A blank cell means the span exceeds the maximum shown in the source table for that size.
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.
Source: International Residential Code (IRC), 2018 — Table R802.4.1(3) — Rafter Spans, 30 psf Ground Snow Load (ceiling not attached, L/180). Published by International Code Council.
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