2×10 floor joist spans (2021 IRC)
Every allowable span the 2021 International Residential Code floor tables list for a 2×10 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 2×10 Southern pine No. 2 floor joist at 16-inch centers spans up to 14’0” 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 11’5”; hold 16-inch centers and switch to Spruce-pine-fir No. 2 and the table lists 15’5”. 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 15’8”.
2×10 floor joists — residential living areas
| 2×10 — species and grade | 12" on center | 16" on center | 19.2" on center | 24" on center |
|---|---|---|---|---|
| Douglas fir-larch Select Structural | 19’1” | 17’4” | 16’4” | 15’2” |
| Douglas fir-larch No. 1 | 18’5” | 16’5” | 15’0” | 13’5” |
| Douglas fir-larch No. 2 | 18’0” | 15’7” | 14’3” | 12’9” |
| Douglas fir-larch No. 3 | 13’9” | 11’11” | 10’11” | 9’9” |
| Hem-fir Select Structural | 18’0” | 16’5” | 15’5” | 14’4” |
| Hem-fir No. 1 | 17’8” | 16’0” | 14’10” | 13’3” |
| Hem-fir No. 2 | 16’10” | 15’2” | 13’10” | 12’5” |
| Hem-fir No. 3 | 13’5” | 11’8” | 10’7” | 9’6” |
| Southern pine Select Structural | 18’9” | 17’0” | 16’0” | 14’11” |
| Southern pine No. 1 | 18’0” | 16’1” | 14’8” | 13’1” |
| Southern pine No. 2 | 16’2” | 14’0” | 12’10” | 11’5” |
| Southern pine No. 3 | 12’6” | 10’10” | 9’10” | 8’10” |
| Spruce-pine-fir Select Structural | 17’8” | 16’0” | 15’1” | 14’0” |
| Spruce-pine-fir No. 1 | 17’3” | 15’5” | 14’1” | 12’7” |
| Spruce-pine-fir No. 2 | 17’3” | 15’5” | 14’1” | 12’7” |
| Spruce-pine-fir No. 3 | 13’5” | 11’8” | 10’7” | 9’6” |
2021 IRC Table R502.3.1(2) — residential living areas, 40 psf live / 10 psf dead / L/360. table source
2×10 floor joists — residential sleeping areas
| 2×10 — species and grade | 12" on center | 16" on center | 19.2" on center | 24" on center |
|---|---|---|---|---|
| Douglas fir-larch Select Structural | 21’0” | 19’1” | 18’0” | 16’8” |
| Douglas fir-larch No. 1 | 20’3” | 18’5” | 16’9” | 15’0” |
| Douglas fir-larch No. 2 | 19’10” | 17’5” | 15’11” | 14’3” |
| Douglas fir-larch No. 3 | 15’5” | 13’4” | 12’2” | 10’11” |
| Hem-fir Select Structural | 19’10” | 18’0” | 17’0” | 15’9” |
| Hem-fir No. 1 | 19’5” | 17’8” | 16’7” | 14’10” |
| Hem-fir No. 2 | 18’6” | 16’10” | 15’6” | 13’10” |
| Hem-fir No. 3 | 15’0” | 13’0” | 11’10” | 10’7” |
| Southern pine Select Structural | 20’8” | 18’9” | 17’8” | 16’5” |
| Southern pine No. 1 | 19’10” | 18’0” | 16’5” | 14’8” |
| Southern pine No. 2 | 18’1” | 15’8” | 14’4” | 12’10” |
| Southern pine No. 3 | 14’0” | 11’1” | 11’0” | 9’10” |
| Spruce-pine-fir Select Structural | 19’5” | 17’8” | 16’7” | 15’5” |
| Spruce-pine-fir No. 1 | 19’0” | 17’2” | 15’8” | 14’1” |
| Spruce-pine-fir No. 2 | 19’0” | 17’2” | 15’8” | 14’1” |
| Spruce-pine-fir No. 3 | 15’0” | 13’0” | 11’10” | 10’7” |
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: 2×6 floor joists · 2×8 floor joists · 2×12 floor joists
The same 2×10 in other assemblies: 2×10 ceiling joists · 2×10 rafters · 2×10 deck joists
Common questions
Can 2×10 floor joists span 17 feet?
At 16-inch centers, 2×10 Southern pine No. 2 is listed at 14’0” in 2021 IRC Table R502.3.1(2) (40 psf live / 10 psf dead / L/360). 12 of the 64 2×10 cells in that table are 17 feet or longer, and the widest spacing among them is 16-inch centers — Southern pine Select Structural at 16 inches is listed at 17’0”.
How far can a 2×10 floor joist span at 24-inch centers?
2021 IRC Table R502.3.1(2) — residential living areas — lists 2×10 No. 2 at 24-inch centers as Douglas fir-larch 12’9”, Hem-fir 12’5”, Southern pine 11’5”, Spruce-pine-fir 12’7”. The same four species in 2021 IRC Table R502.3.1(1) (residential sleeping areas): 14’3”, 13’10”, 12’10”, 14’1”.
What is the difference between the two 2021 IRC floor joist tables for a 2×10?
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 2×10 Southern pine No. 2 at 16-inch centers: 15’8” in the first, 14’0” in the second.