Cantilevered Balcony

[Mark S. Tyson]

I know in the past that Balcony cantilevers has been a hotly debated topic so I'm posting the information below for reference. The information is from the Florida Building Code but is the exact language that is contained in the International Building Code. Hope you find the information useful on your next cantilever deck inspection.

TABLE R502.2.3.3(2) CANTILEVER SPANS FOR FLOOR JOISTS SUPPORTING EXTERIOR BALCONYa, b, e, f

Member Size Spacing Maximum Cantilever Span
(Uplift Force at Backspan Support in lb)c, d 2 × 8 12″ 42″ (139) 2 × 8 16″ 36″ (151) 2 × 10 12″ 61″ (164) 2 × 10 16″ 53″ (180) 2 × 10 24″ 43″ (212) 2 × 12 16″ 72″ (22 2 × 12 24″ 58″ (279)

For SI:1 inch = 25.4 mm, 1 pound per square foot = 0.0479 kPa.

a. Spans are based on No. 2 Grade lumber of Douglas fir-larch, hem-fir, southern pine, and spruce-pine-fir for repetitive (3 or more) members.

b. Ratio of backspan to cantilever span shall be at least 2:1.

c. Connections capable of resisting the indicated uplift force shall be provided at the backspan support.

d. 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).

e. A full-depth rim joist shall be provided at the cantilevered end of the joists. Solid blocking shall be provided at the cantilevered support.

[Mark S. Tyson]

TABLE R502.2.3.3(2) CANTILEVER SPANS FOR FLOOR JOISTS SUPPORTING EXTERIOR BALCONYa, b, e, f

Member Size

Spacing

Maximum Cantilever Span
(Uplift Force at Backspan Support in lb)c, d

2 × 8

12″

42″ (139)

2 × 8

16″

36″ (151)

2 × 10

12″

61″ (164)

2 × 10

16″

53″ (180)

2 × 10

24″

43″ (212)

2 × 12

16″

72″ (22

2 × 12

24″

58″ (279)

For SI:1 inch = 25.4 mm, 1 pound per square foot = 0.0479 kPa.

a. Spans are based on No. 2 Grade lumber of Douglas fir-larch, hem-fir, southern pine, and spruce-pine-fir for repetitive (3 or more) members.

b. Ratio of backspan to cantilever span shall be at least 2:1.

c. Connections capable of resisting the indicated uplift force shall be provided at the backspan support.

d. 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).

e. A full-depth rim joist shall be provided at the cantilevered end of the joists. Solid blocking shall be provided at the cantilevered support.

This should be a bit easier too read