2×6 ceiling joist spans (2021 IRC)
Every allowable span the 2021 International Residential Code ceiling tables list for a 2×6 joist — four species, four grades, four spacings, both attic load cases — each table cited where it sits.
2021 IRC Table R802.5.1(2) covers uninhabitable attics with limited storage; 2021 IRC Table R802.5.1(1) covers uninhabitable attics without storage. Both tables are below, in that order.
A 2×6 Southern pine No. 2 ceiling joist at 16-inch centers spans up to 12’0” in an uninhabitable attic with limited storage (2021 IRC Table R802.5.1(2)). Widen the spacing to 24-inch centers and the same joist is listed at 9’10”; hold 16-inch centers and switch to Spruce-pine-fir No. 2 and the table lists 12’10”. Under 2021 IRC Table R802.5.1(1) — uninhabitable attics without storage, 10 psf live / 5 psf dead / L/240 — that same Southern pine No. 2 at 16 inches is listed at 16’11”.
2×6 ceiling joists — uninhabitable attics with limited storage
| 2×6 — species and grade | 12" on center | 16" on center | 19.2" on center | 24" on center |
|---|---|---|---|---|
| Douglas fir-larch Select Structural | 16’4” | 14’11” | 14’0” | 13’0” |
| Douglas fir-larch No. 1 | 15’9” | 13’9” | 12’6” | 11’2” |
| Douglas fir-larch No. 2 | 15’0” | 13’0” | 11’11” | 10’8” |
| Douglas fir-larch No. 3 | 11’6” | 9’11” | 9’1” | 8’1” |
| Hem-fir Select Structural | 15’6” | 14’1” | 13’3” | 12’3” |
| Hem-fir No. 1 | 15’2” | 13’7” | 12’4” | 11’1” |
| Hem-fir No. 2 | 14’5” | 12’8” | 11’7” | 10’4” |
| Hem-fir No. 3 | 11’2” | 9’8” | 8’10” | 7’11” |
| Southern pine Select Structural | 16’1” | 14’7” | 13’9” | 12’9” |
| Southern pine No. 1 | 15’6” | 14’0” | 12’9” | 11’5” |
| Southern pine No. 2 | 13’11” | 12’0” | 11’0” | 9’10” |
| Southern pine No. 3 | 10’6” | 9’2” | 8’4” | 7’5” |
| Spruce-pine-fir Select Structural | 15’2” | 13’9” | 12’11” | 12’0” |
| Spruce-pine-fir No. 1 | 14’9” | 12’10” | 11’9” | 10’6” |
| Spruce-pine-fir No. 2 | 14’9” | 12’10” | 11’9” | 10’6” |
| Spruce-pine-fir No. 3 | 11’2” | 9’8” | 8’10” | 7’11” |
2021 IRC Table R802.5.1(2) — uninhabitable attics with limited storage, 20 psf live / 10 psf dead / L/240. table source
2×6 ceiling joists — uninhabitable attics without storage
| 2×6 — species and grade | 12" on center | 16" on center | 19.2" on center | 24" on center |
|---|---|---|---|---|
| Douglas fir-larch Select Structural | 20’8” | 18’9” | 17’8” | 16’4” |
| Douglas fir-larch No. 1 | 19’11” | 18’1” | 17’0” | 15’9” |
| Douglas fir-larch No. 2 | 19’6” | 17’8” | 16’8” | 15’0” |
| Douglas fir-larch No. 3 | 16’3” | 14’1” | 12’10” | 11’6” |
| Hem-fir Select Structural | 19’6” | 17’8” | 16’8” | 15’6” |
| Hem-fir No. 1 | 19’1” | 17’4” | 16’4” | 15’2” |
| Hem-fir No. 2 | 18’2” | 16’6” | 15’7” | 14’5” |
| Hem-fir No. 3 | 15’10” | 13’9” | 12’6” | 11’2” |
| Southern pine Select Structural | 20’3” | 18’5” | 17’4” | 16’1” |
| Southern pine No. 1 | 19’6” | 17’8” | 16’8” | 15’6” |
| Southern pine No. 2 | 18’8” | 16’11” | 15’7” | 13’11” |
| Southern pine No. 3 | 14’11” | 12’11” | 11’9” | 10’6” |
| Spruce-pine-fir Select Structural | 19’1” | 17’4” | 16’4” | 15’2” |
| Spruce-pine-fir No. 1 | 18’8” | 16’11” | 15’11” | 14’9” |
| Spruce-pine-fir No. 2 | 18’8” | 16’11” | 15’11” | 14’9” |
| Spruce-pine-fir No. 3 | 15’10” | 13’9” | 12’6” | 11’2” |
2021 IRC Table R802.5.1(1) — uninhabitable attics without storage, 10 psf live / 5 psf dead / L/240. table source
The two attic cases
2021 IRC Table R802.5.1(1) is the uninhabitable attics without storage case: 10 psf live over 5 psf dead, L/240. 2021 IRC Table R802.5.1(2) is the uninhabitable attics with limited storage case: 20 psf live over 10 psf dead, L/240. The dead load is the part that gets skipped — 5 psf where the attic holds no storage, 10 psf where the table allows limited storage — and it is why the same 2×6 carries two different spans on this page.
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. 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 ceiling joist sizes: 2×4 ceiling joists · 2×8 ceiling joists · 2×10 ceiling joists
The same 2×6 in other assemblies: 2×6 floor joists · 2×6 rafters · 2×6 deck joists
Common questions
Can 2×6 ceiling joists span 15 feet?
At 16-inch centers, 2×6 Southern pine No. 2 is listed at 12’0” in 2021 IRC Table R802.5.1(2) (20 psf live / 10 psf dead / L/240). 8 of the 64 2×6 cells in that table are 15 feet or longer, and the widest spacing among them is 12-inch centers — Douglas fir-larch No. 2 at 12 inches is listed at 15’0”.
Do these 2×6 ceiling joist spans allow attic storage?
Two cases, two tables. 2021 IRC Table R802.5.1(1) is the uninhabitable attics without storage case — 10 psf live over 5 psf dead at L/240 — and lists 2×6 Southern pine No. 2 at 16-inch centers at 16’11”. 2021 IRC Table R802.5.1(2) is the uninhabitable attics with limited storage case — 20 psf live over 10 psf dead at L/240 — and lists the same joist at 12’0”.
How far can a 2×6 ceiling joist span at 24-inch centers?
2021 IRC Table R802.5.1(2) — uninhabitable attics with limited storage — lists 2×6 No. 2 at 24-inch centers as Douglas fir-larch 10’8”, Hem-fir 10’4”, Southern pine 9’10”, Spruce-pine-fir 10’6”. The same four in 2021 IRC Table R802.5.1(1) (uninhabitable attics without storage): 15’0”, 14’5”, 13’11”, 14’9”.