Floor cantilever spans shall not exceed the nominal depth of the wood floor joist. Floor cantilevers constructed in accordance with Table R502.3.3(1) shall be permitted where supporting a light-frame bearing wall and roof only. Floor cantilevers supporting an exterior balcony are permitted to be constructed in accordance with Table R502.3.3(2).
TABLE R502.3.3(1)
CANTILEVER SPANS FOR FLOOR JOISTS SUPPORTING LIGHT-FRAME EXTERIOR BEARING WALL AND ROOF ONLYa, b, c, f, g, h
(Floor live load ≤ 40 psf, roof live load ≤ 20 psf)
MEMBER & SPACING
MAXIMUM CANTILEVER SPAN (uplift force at backspan support in lb)d, e
Ground Snow Load
≤ 20 psf
30 psf
50 psf
70 psf
Roof Width
Roof Width
Roof Width
Roof Width
24 ft
32 ft
40 ft
24 ft
32 ft
40 ft
24 ft
32 ft
40 ft
24 ft
32 ft
40 ft
2 × 8 @ 12"
20" (177)
15" (227)
—
18" (209)
—
—
—
—
—
—
—
—
2 × 10 @ 16"
29" (228)
21" (297)
16" (364)
26" (271)
18" (354)
—
20" (375)
—
—
—
—
—
2 × 10 @ 12"
36" (166)
26" (219)
20" (270)
34" (198)
22" (263)
16" (324)
26" (277)
—
—
19" (356)
—
—
2 × 12 @ 16"
—
32" (287)
25" (356)
36" (263)
29" (345)
21" (428)
29" (367)
20" (484)
—
23" (471)
—
—
2 × 12 @ 12"
—
42" (209)
31" (263)
—
37" (253)
27" (317)
36" (271)
27" (358)
17" (447)
31" (348)
19" (462)
—
2 × 12 @ 8"
—
48" (136)
45" (169)
—
48" (164)
38" (206)
—
40" (233)
26" (294)
36" (230)
29" (304)
18" (379)
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
- Tabulated values are for clear-span roof supported solely by exterior bearing walls.
- Spans are based on No. 2 Grade lumber of Douglas fir-larch, Southern pine, hem-fir and spruce-pine-fir for repetitive (three or more) members.
- Ratio of backspan to cantilever span shall be not less than 3:1.
- Connections capable of resisting the indicated uplift force shall be provided at the backspan support.
- Uplift force is for a backspan to cantilever span ratio of 3:1. Tabulated uplift values are permitted to be reduced by multiplying by a factor equal to 3 divided by the actual backspan ratio provided (3/backspan ratio).
- See Section R301.2.2.6, Item 1, for additional limitations on cantilevered floor joists for detached one- and two-family dwellings in Seismic Design Category D0, D1 or D2 and townhouses in Seismic Design Category C, D0, D1 or D2.
- A full-depth rim joist shall be provided at the unsupported end of the cantilever joists. Solid blocking shall be provided at the supported end. Where the cantilever length is 24 inches or less and the building is assigned to Seismic Design Category A, B or C, solid blocking at the support for the cantilever shall not be required.
- Linear interpolation shall be permitted for building widths and ground snow loads other than shown.
TABLE R502.3.3(2)a, b, e, f
MEMBER SIZE
SPACING
MAXIMUM CANTILEVER SPAN (uplift force at backspan support in lb)c, d
Ground Snow Load
≤ 30 psf
50 psf
70 psf
2 × 8
12"
42" (139)
39" (156)
34" (165)
2 × 8
16"
36" (151)
34" (171)
29" (180)
2 × 10
12"
61" (164)
57" (189)
49" (201)
2 × 10
16"
53" (180)
49" (208)
42" (220)
2 × 10
24"
43" (212)
40" (241)
34" (255)
2 × 12
16"
72" (228)
67" (260)
57" (268)
2 × 12
24"
58" (279)
54" (319)
47" (330)
For SI: 1 inch = 25.4 mm, 1 pound per square foot = 0.0479 kPa.
- Spans are based on No. 2 Grade lumber of Douglas fir-larch, Southern pine, hem-fir, and spruce-pine-fir for repetitive (three or more) members.
- Ratio of backspan to cantilever span shall be not less than 2:1.
- Connections capable of resisting the indicated uplift force shall be provided at the backspan support.
- Uplift force is for a backspan to cantilever span ratio of 2:1. Tabulated uplift values are permitted to be reduced by multiplying by a factor equal to 2 divided by the actual backspan ratio provided (2/backspan ratio).
- A full-depth rim joist shall be provided at the unsupported end of the cantilever joists. Solid blocking shall be provided at the supported end. Where the cantilever length is 24 inches or less and the building is assigned to Seismic Design Category A, B or C, solid blocking at the support for the cantilever shall not be required.
- Linear interpolation shall be permitted for ground snow loads other than shown.