2×6 floor joist spans (2021 IRC)
Every allowable span the 2021 International Residential Code floor tables list for a 2×6 joist — four species, four grades, four spacings, both load cases — each table cited where it sits.
2021 IRC Table R502.3.1(2) covers residential living areas; 2021 IRC Table R502.3.1(1) covers residential sleeping areas. Both tables are below, in that order.
A 2×6 Southern pine No. 2 floor joist at 16-inch centers spans up to 9’4” under standard residential living-area loads (2021 IRC Table R502.3.1(2)). Widen the spacing to 24-inch centers and the same joist is listed at 7’7”; hold 16-inch centers and switch to Spruce-pine-fir No. 2 and the table lists the same 9’4”. Under 2021 IRC Table R502.3.1(1) — residential sleeping areas, 30 psf live / 10 psf dead / L/360 — that same Southern pine No. 2 at 16 inches is listed at 10’3”.
2×6 floor joists — residential living areas
| 2×6 — species and grade | 12" on center | 16" on center | 19.2" on center | 24" on center |
|---|---|---|---|---|
| Douglas fir-larch Select Structural | 11’4” | 10’4” | 9’8” | 9’0” |
| Douglas fir-larch No. 1 | 10’11” | 9’11” | 9’4” | 8’8” |
| Douglas fir-larch No. 2 | 10’9” | 9’9” | 9’2” | 8’3” |
| Douglas fir-larch No. 3 | 8’11” | 7’8” | 7’0” | 6’3” |
| Hem-fir Select Structural | 10’9” | 9’9” | 9’2” | 8’6” |
| Hem-fir No. 1 | 10’6” | 9’6” | 9’0” | 8’4” |
| Hem-fir No. 2 | 10’0” | 9’1” | 8’7” | 7’11” |
| Hem-fir No. 3 | 8’8” | 7’6” | 6’10” | 6’2” |
| Southern pine Select Structural | 11’2” | 10’2” | 9’6” | 8’10” |
| Southern pine No. 1 | 10’9” | 9’9” | 9’2” | 8’6” |
| Southern pine No. 2 | 10’3” | 9’4” | 8’6” | 7’7” |
| Southern pine No. 3 | 8’2” | 7’1” | 6’5” | 5’9” |
| Spruce-pine-fir Select Structural | 10’6” | 9’6” | 9’0” | 8’4” |
| Spruce-pine-fir No. 1 | 10’3” | 9’4” | 8’9” | 8’1” |
| Spruce-pine-fir No. 2 | 10’3” | 9’4” | 8’9” | 8’1” |
| Spruce-pine-fir No. 3 | 8’8” | 7’6” | 6’10” | 6’2” |
2021 IRC Table R502.3.1(2) — residential living areas, 40 psf live / 10 psf dead / L/360. table source
2×6 floor joists — residential sleeping areas
| 2×6 — species and grade | 12" on center | 16" on center | 19.2" on center | 24" on center |
|---|---|---|---|---|
| Douglas fir-larch Select Structural | 12’6” | 11’4” | 10’8” | 9’11” |
| Douglas fir-larch No. 1 | 12’0” | 10’11” | 10’4” | 9’7” |
| Douglas fir-larch No. 2 | 11’10” | 10’9” | 10’1” | 9’3” |
| Douglas fir-larch No. 3 | 9’11” | 8’7” | 7’10” | 7’0” |
| Hem-fir Select Structural | 11’10” | 10’9” | 10’1” | 9’4” |
| Hem-fir No. 1 | 11’7” | 10’6” | 9’10” | 9’2” |
| Hem-fir No. 2 | 11’0” | 10’0” | 9’5” | 8’9” |
| Hem-fir No. 3 | 9’8” | 8’5” | 7’8” | 6’10” |
| Southern pine Select Structural | 12’3” | 11’2” | 10’6” | 9’9” |
| Southern pine No. 1 | 11’10” | 10’9” | 10’1” | 9’4” |
| Southern pine No. 2 | 11’3” | 10’3” | 9’6” | 8’6” |
| Southern pine No. 3 | 9’2” | 7’11” | 7’3” | 6’5” |
| Spruce-pine-fir Select Structural | 11’7” | 10’6” | 9’10” | 9’2” |
| Spruce-pine-fir No. 1 | 11’3” | 10’3” | 9’8” | 8’11” |
| Spruce-pine-fir No. 2 | 11’3” | 10’3” | 9’8” | 8’11” |
| Spruce-pine-fir No. 3 | 9’8” | 8’5” | 7’8” | 6’10” |
2021 IRC Table R502.3.1(1) — residential sleeping areas, 30 psf live / 10 psf dead / L/360. table source
What these tables state
Each number is the span the code table lists for that species, grade, and on-center spacing at the load case stamped at the top of this page: 40 psf live / 10 psf dead / L/360 for residential living areas, 30 psf live / 10 psf dead / L/360 for residential sleeping areas. Change the spacing, the grade, or the species and you are reading a different cell of the same table.
Point loads, cantilevers beyond the table footnotes, unusual snow loads, or anything else outside the table's stated conditions — that's an engineer's question.
Other sizes and assemblies
Other floor joist sizes: 2×8 floor joists · 2×10 floor joists · 2×12 floor joists
The same 2×6 in other assemblies: 2×6 ceiling joists · 2×6 rafters · 2×6 deck joists
Common questions
Can 2×6 floor joists span 12 feet?
At 16-inch centers, 2×6 Southern pine No. 2 is listed at 9’4” in 2021 IRC Table R502.3.1(2) (40 psf live / 10 psf dead / L/360). No 2×6 cell in that table reaches 12 feet — the longest listed is 11’4”, Douglas fir-larch Select Structural at 12-inch centers.
How far can a 2×6 floor joist span at 24-inch centers?
2021 IRC Table R502.3.1(2) — residential living areas — lists 2×6 No. 2 at 24-inch centers as Douglas fir-larch 8’3”, Hem-fir 7’11”, Southern pine 7’7”, Spruce-pine-fir 8’1”. The same four species in 2021 IRC Table R502.3.1(1) (residential sleeping areas): 9’3”, 8’9”, 8’6”, 8’11”.
What is the difference between the two 2021 IRC floor joist tables for a 2×6?
2021 IRC Table R502.3.1(1) covers residential sleeping areas at 30 psf live / 10 psf dead / L/360; 2021 IRC Table R502.3.1(2) covers residential living areas at 40 psf live / 10 psf dead / L/360. Same 2×6 Southern pine No. 2 at 16-inch centers: 10’3” in the first, 9’4” in the second.