Roof rafter span tables (2021 IRC)

The two ceiling-not-attached rafter tables this site carries, in full: 2021 IRC Table R802.4.1(1) for roof live load 20 psf and 2021 IRC Table R802.4.1(3) for ground snow load 30 psf, both with the ceiling not attached to the rafters. Every size, every species, every grade, every on-center spacing — each table cited where it sits, with a link down to the page for each size.

30 psf ground snow / 10 psf dead / L/180, ceiling not attached 20 psf roof live / 10 psf dead / L/180, ceiling not attached

30 psf ground snow / 10 psf dead / L/180

14’2”

Per 2021 IRC Table R802.4.1(3) — ground snow load 30 psf, ceiling not attached to rafters, 30 psf ground snow / 10 psf dead / L/180.

A 2×8 Southern pine No. 2 rafter at 16-inch centers spans up to 14’2” where the ground snow load is 30 psf and the ceiling is not attached to the rafters (2021 IRC Table R802.4.1(3)). Under 2021 IRC Table R802.4.1(1) — roof live load 20 psf, ceiling not attached to rafters, 20 psf roof live / 10 psf dead / L/180 — the same rafter is listed at 17’1”.

What these two tables cover, and what they do not

Both tables here are ceiling-not-attached cases: the ceiling is not fastened to the rafters, and the rafter is checked at L/180. 2021 IRC Table R802.4.1(1) is roof live load 20 psf at 20 psf roof live / 10 psf dead / L/180. 2021 IRC Table R802.4.1(3) is ground snow load 30 psf at 30 psf ground snow / 10 psf dead / L/180.

The 2021 IRC R802.4.1 set carries eight rafter span tables. Two are quoted on this site; the other six load variants — the attached-ceiling cases and the heavier ground snow loads — are not covered here, and no number on this page is stretched to stand in for them.

Where the rafter ties are raised above the wall plates, the allowable rafter span is reduced per 2021 IRC Table R802.4.1(9) (table source). The spans on this page do not carry that reduction, and this page does not restate that table's factors. 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.

The common case, size by size

No. 2 grade at 16-inch centers at 30 psf ground snow, ceiling not attached, across the 4 species 2021 IRC Table R802.4.1(3) lists. Each size links to its own page, where the full table for that size sits alongside the 20 psf roof live load table.

Rafter size	Douglas fir-larch	Hem-fir	Southern pine	Spruce-pine-fir
2×4 rafters	8’3”	8’0”	7’6”	8’2”
2×6 rafters	12’1”	11’9”	11’2”	11’11”
2×8 rafters	15’4”	14’11”	14’2”	15’1”
2×10 rafters	18’9”	18’2”	16’10”	18’5”
2×12 rafters	21’8”	21’1”	19’10”	21’5”

2021 IRC Table R802.4.1(3) — ground snow load 30 psf, ceiling not attached to rafters, 30 psf ground snow / 10 psf dead / L/180, No. 2 grade at 16-inch centers. table source

Ground snow load 30 psf, ceiling not attached — the full table

2021 IRC Table R802.4.1(3), every size the table covers. Spacing runs across the top; species and grade run down the side; the blocks are the lumber sizes. Cells that read 26’+ are spans the table lists as exceeding 26 feet.

Species and grade	12" on center	16" on center	19.2" on center	24" on center
2×4 rafters
Douglas fir-larch Select Structural	10’0”	9’1”	8’7”	8’0”
Douglas fir-larch No. 1	9’8”	8’9”	7’11”	7’1”
Douglas fir-larch No. 2	9’6”	8’3”	7’7”	6’9”
Douglas fir-larch No. 3	7’3”	6’4”	5’9”	5’2”
Hem-fir Select Structural	9’6”	8’7”	8’1”	7’6”
Hem-fir No. 1	9’3”	8’5”	7’10”	7’0”
Hem-fir No. 2	8’10”	8’0”	7’4”	6’7”
Hem-fir No. 3	7’1”	6’2”	5’7”	5’0”
Southern pine Select Structural	9’10”	8’11”	8’5”	7’10”
Southern pine No. 1	9’6”	8’7”	8’0”	7’1”
Southern pine No. 2	8’7”	7’6”	6’10”	6’1”
Southern pine No. 3	6’7”	5’9”	5’3”	4’8”
Spruce-pine-fir Select Structural	9’3”	8’5”	7’11”	7’4”
Spruce-pine-fir No. 1	9’1”	8’2”	7’5”	6’8”
Spruce-pine-fir No. 2	9’1”	8’2”	7’5”	6’8”
Spruce-pine-fir No. 3	7’1”	6’2”	5’7”	5’0”
2×6 rafters
Douglas fir-larch Select Structural	15’9”	14’4”	13’6”	12’6”
Douglas fir-larch No. 1	14’9”	12’9”	11’8”	10’5”
Douglas fir-larch No. 2	14’0”	12’1”	11’0”	9’10”
Douglas fir-larch No. 3	10’8”	9’3”	8’5”	7’7”
Hem-fir Select Structural	14’10”	13’6”	12’9”	11’10”
Hem-fir No. 1	14’6”	12’7”	11’6”	10’3”
Hem-fir No. 2	13’7”	11’9”	10’9”	9’7”
Hem-fir No. 3	10’5”	9’0”	8’3”	7’4”
Southern pine Select Structural	15’6”	14’1”	13’3”	12’3”
Southern pine No. 1	14’10”	13’0”	11’10”	10’7”
Southern pine No. 2	12’11”	11’2”	10’2”	9’2”
Southern pine No. 3	9’9”	8’6”	7’9”	6’11”
Spruce-pine-fir Select Structural	14’7”	13’3”	12’5”	11’7”
Spruce-pine-fir No. 1	13’9”	11’11”	10’11”	9’9”
Spruce-pine-fir No. 2	13’9”	11’11”	10’11”	9’9”
Spruce-pine-fir No. 3	10’5”	9’0”	8’3”	7’4”
2×8 rafters
Douglas fir-larch Select Structural	20’9”	18’10”	17’9”	16’2”
Douglas fir-larch No. 1	18’8”	16’2”	14’9”	13’2”
Douglas fir-larch No. 2	17’8”	15’4”	14’0”	12’6”
Douglas fir-larch No. 3	13’6”	11’8”	10’8”	9’7”
Hem-fir Select Structural	19’7”	17’10”	16’9”	15’7”
Hem-fir No. 1	18’5”	15’11”	14’7”	13’0”
Hem-fir No. 2	17’2”	14’11”	13’7”	12’2”
Hem-fir No. 3	13’2”	11’5”	10’5”	9’4”
Southern pine Select Structural	20’5”	18’6”	17’5”	16’2”
Southern pine No. 1	19’0”	16’6”	15’1”	13’5”
Southern pine No. 2	16’4”	14’2”	12’11”	11’7”
Southern pine No. 3	12’4”	10’8”	9’9”	8’9”
Spruce-pine-fir Select Structural	19’2”	17’5”	16’5”	14’9”
Spruce-pine-fir No. 1	17’5”	15’1”	13’9”	12’4”
Spruce-pine-fir No. 2	17’5”	15’1”	13’9”	12’4”
Spruce-pine-fir No. 3	13’2”	11’5”	10’5”	9’4”
2×10 rafters
Douglas fir-larch Select Structural	26’+	24’1”	22’1”	19’9”
Douglas fir-larch No. 1	22’9”	19’9”	18’0”	16’1”
Douglas fir-larch No. 2	21’7”	18’9”	17’1”	15’3”
Douglas fir-larch No. 3	16’6”	14’3”	13’1”	11’8”
Hem-fir Select Structural	25’0”	22’9”	21’4”	19’1”
Hem-fir No. 1	22’6”	19’6”	17’9”	15’11”
Hem-fir No. 2	21’0”	18’2”	16’7”	14’10”
Hem-fir No. 3	16’1”	13’11”	12’9”	11’5”
Southern pine Select Structural	26’+	23’8”	22’3”	20’0”
Southern pine No. 1	22’3”	19’3”	17’7”	15’9”
Southern pine No. 2	19’5”	16’10”	15’4”	13’9”
Southern pine No. 3	15’0”	13’0”	11’10”	10’7”
Spruce-pine-fir Select Structural	24’6”	22’1”	20’2”	18’0”
Spruce-pine-fir No. 1	21’4”	18’5”	16’10”	15’1”
Spruce-pine-fir No. 2	21’4”	18’5”	16’10”	15’1”
Spruce-pine-fir No. 3	16’1”	13’11”	12’9”	11’5”
2×12 rafters
Douglas fir-larch Select Structural	26’+	26’+	25’7”	22’10”
Douglas fir-larch No. 1	26’+	22’10”	20’11”	18’8”
Douglas fir-larch No. 2	25’1”	21’8”	19’10”	17’9”
Douglas fir-larch No. 3	19’2”	16’7”	15’2”	13’6”
Hem-fir Select Structural	26’+	26’+	24’8”	22’1”
Hem-fir No. 1	26’0”	22’7”	20’7”	18’5”
Hem-fir No. 2	24’4”	21’1”	19’3”	17’3”
Hem-fir No. 3	18’8”	16’2”	14’9”	13’2”
Southern pine Select Structural	26’+	26’+	26’+	23’7”
Southern pine No. 1	26’+	22’10”	20’11”	18’8”
Southern pine No. 2	22’10”	19’10”	18’1”	16’2”
Southern pine No. 3	17’9”	15’4”	14’0”	12’6”
Spruce-pine-fir Select Structural	26’+	25’7”	23’4”	20’11”
Spruce-pine-fir No. 1	24’8”	21’5”	19’6”	17’6”
Spruce-pine-fir No. 2	24’8”	21’5”	19’6”	17’6”
Spruce-pine-fir No. 3	18’8”	16’2”	14’9”	13’2”

2021 IRC Table R802.4.1(3) — ground snow load 30 psf, ceiling not attached to rafters, 30 psf ground snow / 10 psf dead / L/180. table source

Roof live load 20 psf, ceiling not attached — the full table

2021 IRC Table R802.4.1(1), on the 20 psf roof live / 10 psf dead / L/180, ceiling not attached basis, every size the table covers. Across the 320 cells the two tables share, 2021 IRC Table R802.4.1(1) lists a longer span than 2021 IRC Table R802.4.1(3) in 307 of them and the same span in 13 — never a shorter one.

Species and grade	12" on center	16" on center	19.2" on center	24" on center
2×4 rafters
Douglas fir-larch Select Structural	11’6”	10’5”	9’10”	9’1”
Douglas fir-larch No. 1	11’1”	10’0”	9’5”	8’7”
Douglas fir-larch No. 2	10’10”	9’10”	9’1”	8’2”
Douglas fir-larch No. 3	8’9”	7’7”	6’11”	6’2”
Hem-fir Select Structural	10’10”	9’10”	9’3”	8’7”
Hem-fir No. 1	10’7”	9’8”	9’1”	8’5”
Hem-fir No. 2	10’1”	9’2”	8’8”	7’11”
Hem-fir No. 3	8’7”	7’5”	6’9”	6’1”
Southern pine Select Structural	11’3”	10’3”	9’8”	8’11”
Southern pine No. 1	10’10”	9’10”	9’3”	8’7”
Southern pine No. 2	10’4”	9’0”	8’2”	7’4”
Southern pine No. 3	8’0”	6’11”	6’4”	5’8”
Spruce-pine-fir Select Structural	10’7”	9’8”	9’1”	8’5”
Spruce-pine-fir No. 1	10’4”	9’5”	8’10”	8’0”
Spruce-pine-fir No. 2	10’4”	9’5”	8’10”	8’0”
Spruce-pine-fir No. 3	8’7”	7’5”	6’9”	6’1”
2×6 rafters
Douglas fir-larch Select Structural	18’0”	16’4”	15’5”	14’4”
Douglas fir-larch No. 1	17’4”	15’4”	14’0”	12’6”
Douglas fir-larch No. 2	16’10”	14’7”	13’3”	11’11”
Douglas fir-larch No. 3	12’10”	11’1”	10’2”	9’1”
Hem-fir Select Structural	17’0”	15’6”	14’7”	13’6”
Hem-fir No. 1	16’8”	15’2”	13’10”	12’4”
Hem-fir No. 2	15’11”	14’2”	12’11”	11’7”
Hem-fir No. 3	12’6”	10’10”	9’11”	8’10”
Southern pine Select Structural	17’8”	16’1”	15’2”	14’1”
Southern pine No. 1	17’0”	15’6”	14’3”	12’9”
Southern pine No. 2	15’7”	13’6”	12’3”	11’0”
Southern pine No. 3	11’9”	10’2”	9’4”	8’4”
Spruce-pine-fir Select Structural	16’8”	15’2”	14’3”	13’3”
Spruce-pine-fir No. 1	16’3”	14’4”	13’1”	11’9”
Spruce-pine-fir No. 2	16’3”	14’4”	13’1”	11’9”
Spruce-pine-fir No. 3	12’6”	10’10”	9’11”	8’10”
2×8 rafters
Douglas fir-larch Select Structural	23’9”	21’7”	20’4”	18’10”
Douglas fir-larch No. 1	22’5”	19’5”	17’9”	15’10”
Douglas fir-larch No. 2	21’4”	18’5”	16’10”	15’1”
Douglas fir-larch No. 3	16’3”	14’1”	12’10”	11’6”
Hem-fir Select Structural	22’5”	20’5”	19’2”	17’10”
Hem-fir No. 1	22’0”	19’2”	17’6”	15’8”
Hem-fir No. 2	20’8”	17’11”	16’4”	14’8”
Hem-fir No. 3	15’10”	13’9”	12’7”	11’3”
Southern pine Select Structural	23’4”	21’2”	19’11”	18’6”
Southern pine No. 1	22’5”	19’10”	18’1”	16’2”
Southern pine No. 2	19’8”	17’1”	15’7”	13’11”
Southern pine No. 3	14’10”	12’10”	11’9”	10’6”
Spruce-pine-fir Select Structural	21’11”	19’11”	18’9”	17’5”
Spruce-pine-fir No. 1	21’0”	18’2”	16’7”	14’10”
Spruce-pine-fir No. 2	21’0”	18’2”	16’7”	14’10”
Spruce-pine-fir No. 3	15’10”	13’9”	12’7”	11’3”
2×10 rafters
Douglas fir-larch Select Structural	26’+	26’+	25’11”	23’9”
Douglas fir-larch No. 1	26’+	23’9”	21’8”	19’5”
Douglas fir-larch No. 2	26’0”	22’6”	20’7”	18’5”
Douglas fir-larch No. 3	19’10”	17’2”	15’8”	14’1”
Hem-fir Select Structural	26’+	26’+	24’6”	22’9”
Hem-fir No. 1	26’+	23’5”	21’5”	19’2”
Hem-fir No. 2	25’3”	21’11”	20’0”	17’10”
Hem-fir No. 3	19’5”	16’9”	15’4”	13’8”
Southern pine Select Structural	26’+	26’+	25’5”	23’8”
Southern pine No. 1	26’+	23’2”	21’2”	18’11”
Southern pine No. 2	23’5”	20’3”	18’6”	16’6”
Southern pine No. 3	18’0”	15’7”	14’3”	12’9”
Spruce-pine-fir Select Structural	26’+	25’5”	23’11”	21’8”
Spruce-pine-fir No. 1	25’8”	22’3”	20’3”	18’2”
Spruce-pine-fir No. 2	25’8”	22’3”	20’3”	18’2”
Spruce-pine-fir No. 3	19’5”	16’9”	15’4”	13’8”
2×12 rafters
Douglas fir-larch Select Structural	26’+	26’+	26’+	26’+
Douglas fir-larch No. 1	26’+	26’+	25’2”	22’6”
Douglas fir-larch No. 2	26’+	26’0”	23’10”	21’4”
Douglas fir-larch No. 3	23’0”	19’11”	18’3”	16’3”
Hem-fir Select Structural	26’+	26’+	26’+	26’+
Hem-fir No. 1	26’+	26’+	24’10”	22’2”
Hem-fir No. 2	26’+	25’5”	23’2”	20’9”
Hem-fir No. 3	22’6”	19’6”	17’9”	15’11”
Southern pine Select Structural	26’+	26’+	26’+	26’+
Southern pine No. 1	26’+	26’+	25’2”	22’6”
Southern pine No. 2	26’+	23’10”	21’9”	19’6”
Southern pine No. 3	21’4”	18’6”	16’10”	15’1”
Spruce-pine-fir Select Structural	26’+	26’+	26’+	25’2”
Spruce-pine-fir No. 1	26’+	25’9”	23’6”	21’0”
Spruce-pine-fir No. 2	26’+	25’9”	23’6”	21’0”
Spruce-pine-fir No. 3	22’6”	19’6”	17’9”	15’11”

2021 IRC Table R802.4.1(1) — roof live load 20 psf, ceiling not attached to rafters, 20 psf roof live / 10 psf dead / L/180. table source

Common questions

Which rafter tables are on this page?

Two of the eight rafter span tables in the 2021 IRC R802.4.1 set: 2021 IRC Table R802.4.1(1) (20 psf roof live / 10 psf dead / L/180) and 2021 IRC Table R802.4.1(3) (30 psf ground snow / 10 psf dead / L/180). Both are ceiling-not-attached cases — the ceiling is not fastened to the rafters. The other six load variants in that set are not covered on this site; for those, read the code or ask an engineer.

How far can a rafter span?

For Southern pine No. 2 at 16-inch centers where the ground snow load is 30 psf and the ceiling is not attached to the rafters (2021 IRC Table R802.4.1(3)), the table lists 2×4 7’6”, 2×6 11’2”, 2×8 14’2”, 2×10 16’10”, 2×12 19’10”. Under the 20 psf roof live load case (2021 IRC Table R802.4.1(1)) the same rafters are listed at 2×4 9’0”, 2×6 13’6”, 2×8 17’1”, 2×10 20’3”, 2×12 23’10”.

Is there a separate roof rafter span chart?

No. A "rafter span chart" is not a document apart from the code — 2021 IRC Table R802.4.1(1) and 2021 IRC Table R802.4.1(3) are it, and both are printed in full on this page, every size, species, grade and on-center spacing. Every cell is a maximum allowable span under the load case stamped above the table it sits in, which is the one thing that changes between the charts published elsewhere. Each size also has its own page, linked from the table below.

How far apart are roof trusses?

The truss designer sets it, and the number is on the truss design drawings — not in a span table. A roof truss is not a rafter, and neither table on this page covers one. Under 2021 IRC R802.10.2: A wood truss is designed in accordance with accepted engineering practice — a metal-plate-connected truss to ANSI/TPI 1 — with the drawings prepared by a registered design professional wherever the jurisdiction's statutes require one. Under R802.10.1: Wood roof trusses go up only after their truss design drawings have been approved by the building official, the drawings ship to the site with the trusses, and the first thing they must state is the truss's slope or depth, span and spacing. So the spacing is read off the approved drawings that arrive with the trusses. The rafter tables here list rafters at 12, 16, 19.2 or 24-inch centers; those spacings do not carry over to trusses.

What changes if the rafter ties are raised above the wall plates?

The allowable rafter span is reduced, per 2021 IRC Table R802.4.1(9). The spans on this page do not carry that reduction, and this site does not restate that table's factors — read them in the code. 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.

Why are rafter spans checked at a different deflection limit than joists?

Each table states its own limit. Both rafter tables here hold deflection to L/180; the ceiling joist tables hold L/240; the floor joist tables hold L/360. That is one reason the same stick of lumber lists a different span in each assembly's table, and why a rafter span cannot be read off a floor table.

The rest of the framing

Rafter sizes: 2×4 rafters · 2×6 rafters · 2×8 rafters · 2×10 rafters · 2×12 rafters

Other assemblies: floor joist span tables · ceiling joist span tables · deck joist span tables · deck beam spans · header and girder spans

Local codes amend these tables and your inspector has the final word — confirm with your building department.