Ceiling Joists - 20 psf Live Load (Limited Attic Storage)
Ceiling joists for attics with limited storage. Covers Douglas Fir-Larch and Hem-Fir per the published source table. A blank cell means the span exceeds the maximum shown in the source table for that size.
Source: International Residential Code (IRC), 2018 - Table R802.5.1(2) - Ceiling Joist Spans, 20 psf Live Load (limited attic storage). Published by International Code Council.
Edition: These values are transcribed from the IRC 2018 tables. The ICC has since published IRC 2021 and IRC 2024, and the edition in force varies by jurisdiction - confirm the table and edition adopted by your local building department before relying on a span.
Two guides build on this table: rafter vs joist sets it against the floor and rafter tables, and attic storage vs an attic floor explains where limited storage ends and the floor table takes over.
Spacing
Species & grade
2x4
2x6
2x8
2x10
12″ o.c.
Douglas Fir-Larch · SS
10′-5″
16′-4″
21′-7″
-
12″ o.c.
Douglas Fir-Larch · #1
10′-0″
15′-9″
20′-1″
24′-6″
12″ o.c.
Douglas Fir-Larch · #2
9′-10″
15′-0″
19′-1″
23′-3″
12″ o.c.
Douglas Fir-Larch · #3
7′-10″
11′-6″
14′-7″
17′-9″
12″ o.c.
Hem-Fir · SS
9′-10″
15′-6″
20′-5″
-
12″ o.c.
Hem-Fir · #1
9′-8″
15′-2″
19′-10″
24′-3″
12″ o.c.
Hem-Fir · #2
9′-2″
14′-5″
18′-6″
22′-7″
12″ o.c.
Hem-Fir · #3
7′-8″
11′-2″
14′-2″
17′-4″
16″ o.c.
Douglas Fir-Larch · SS
9′-6″
14′-11″
19′-7″
25′-0″
16″ o.c.
Douglas Fir-Larch · #1
9′-1″
13′-9″
17′-5″
21′-3″
16″ o.c.
Douglas Fir-Larch · #2
8′-11″
13′-0″
16′-6″
20′-2″
16″ o.c.
Douglas Fir-Larch · #3
6′-10″
9′-11″
12′-7″
15′-5″
16″ o.c.
Hem-Fir · SS
8′-11″
14′-1″
18′-6″
23′-8″
16″ o.c.
Hem-Fir · #1
8′-9″
13′-7″
17′-2″
21′-0″
16″ o.c.
Hem-Fir · #2
8′-4″
12′-8″
16′-0″
19′-7″
16″ o.c.
Hem-Fir · #3
6′-8″
9′-8″
12′-4″
15′-0″
19.2″ o.c.
Douglas Fir-Larch · SS
8′-11″
14′-0″
18′-5″
23′-7″
19.2″ o.c.
Douglas Fir-Larch · #1
8′-7″
12′-6″
15′-10″
19′-5″
19.2″ o.c.
Douglas Fir-Larch · #2
8′-2″
11′-11″
15′-1″
18′-5″
19.2″ o.c.
Douglas Fir-Larch · #3
6′-2″
9′-1″
11′-6″
14′-1″
19.2″ o.c.
Hem-Fir · SS
8′-5″
13′-3″
17′-5″
22′-3″
19.2″ o.c.
Hem-Fir · #1
8′-3″
12′-4″
15′-8″
19′-2″
19.2″ o.c.
Hem-Fir · #2
7′-10″
11′-7″
14′-8″
17′-10″
19.2″ o.c.
Hem-Fir · #3
6′-1″
8′-10″
11′-3″
13′-8″
24″ o.c.
Douglas Fir-Larch · SS
8′-3″
13′-0″
17′-2″
21′-3″
24″ o.c.
Douglas Fir-Larch · #1
7′-8″
11′-2″
14′-2″
17′-4″
24″ o.c.
Douglas Fir-Larch · #2
7′-3″
10′-8″
13′-6″
16′-5″
24″ o.c.
Douglas Fir-Larch · #3
5′-7″
8′-1″
10′-3″
12′-7″
24″ o.c.
Hem-Fir · SS
7′-10″
12′-3″
16′-2″
20′-6″
24″ o.c.
Hem-Fir · #1
7′-7″
11′-1″
14′-0″
17′-1″
24″ o.c.
Hem-Fir · #2
7′-1″
10′-4″
13′-1″
16′-0″
24″ o.c.
Hem-Fir · #3
5′-5″
7′-11″
10′-0″
12′-3″
Ceiling Joists - 20 psf Live Load (Limited Attic Storage). Live load 20 psf, dead load 10 psf, deflection limit L/240. Spans in feet-inches; “-” means the source leaves that cell blank.
L/240. The L is the span itself and the number underneath is the fraction of that span the member is allowed to bend under the table's design load, so two tables can cover the same lumber and the same load and still publish different spans purely because one allows more bend than the other.
What loading does this table use?
20 psf live load plus 10 psf dead load. That load case is what the table was published for: Ceiling joists for attics with limited storage. Covers Douglas Fir-Larch and Hem-Fir per the published source table.
Can I interpolate between joist spacings?
No. The source table (International Residential Code (IRC), 2018 - Table R802.5.1(2) - Ceiling Joist Spans, 20 psf Live Load (limited attic storage) (International Code Council).) publishes a separate span only at the listed on-center spacings, and every figure on this site is a verbatim cell from that table - nothing is computed or interpolated. If your layout falls between two published spacings, the wider spacing's shorter span is the one the table supports.