Strength - Live Load of 30 psf plus
Dead Load of 20 psf determines the required bending design value
Deflection - For 30 psf live load.
Limited to span in inches divided by 240.
Size Spacing
(in) (in) Rafter Bending Design Value, Fb, (psi)
300 400 500 600 700 800 900 1000 1100 1200
1300 1400 1500 1600 1700 1800 1900 2000
2100 2200 2300 2400 2500 2600 2700
12.0 5- 6 6- 4 7- 1 7- 9 8- 5 9- 0 9- 6 10- 0 10- 6 11- 0 11- 5 11-11 12- 4 12- 8 13- 1 13- 6 13-10 14- 2 14- 7 14-11 15- 3 15- 7 15-11
16.0 4- 9 5- 6 6- 2 6- 9 7- 3 7- 9 8- 3 8- 8 9- 1 9- 6 9-11 10- 3 10- 8 11- 0 11- 4 11- 8 12- 0 12- 4 12- 7 12-11 13- 2 13- 6 13- 9 14- 0 14- 3
2x 6 19.2 4- 4 5- 0 5- 7 6- 2 6- 8 7- 1 7- 6 7-11 8- 4 8- 8 9- 1 9- 5 9- 9 10- 0 10- 4 10- 8 10-11 11- 3 11- 6 11- 9 12- 0 12- 4 12- 7 12-10 13- 1
24.0 3-11 4- 6 5- 0 5- 6 5-11 6- 4 6- 9 7- 1 7- 5 7- 9 8- 1 8- 5 8- 8 9- 0 9- 3 9- 6 9- 9 10- 0 10- 3 10- 6 10- 9 11- 0 11- 3 11- 5 11- 8
12.0 7- 3 8- 4 9- 4 10- 3 11- 1 11-10 12- 7 13- 3 13-11 14- 6 15- 1 15- 8 16- 3 16- 9 17- 3 17- 9 18- 3 18- 9 19- 2 19- 8 20- 1 20- 6 20-11
16.0 6- 3 7- 3 8- 1 8-11 9- 7 10- 3 10-10 11- 6 12- 0 12- 7 13- 1 13- 7 14- 0 14- 6 14-11 15- 5 15-10 16- 3 16- 7 17- 0 17- 5 17- 9 18- 1 18- 6 18-10
2x 8 19.2 5- 9 6- 7 7- 5 8- 1 8- 9 9- 4 9-11 10- 6 11- 0 11- 6 11-11 12- 5 12-10
13- 3 13- 8 14- 0 14- 5 14-10 15- 2 15- 6 15-10
16- 3 16- 7 16-10 17- 2
24.0 5- 2 5-11 6- 7 7- 3 7-10 8- 4 8-11 9- 4 9-10 10- 3 10- 8 11- 1 11- 6 11-10 12- 2 12- 7 12-11 13- 3 13- 7 13-11 14- 2 14- 6 14-10 15- 1 15- 5
12.0 9- 3 10- 8 11-11 13- 1 14- 2 15- 1 16- 0 16-11 17- 9 18- 6 19- 3 20- 0 20- 8 21- 4 22- 0 22- 8 23- 3 23-11 24- 6 25- 1 25- 7
16.0 8- 0 9- 3 10- 4 11- 4 12- 3 13- 1 13-10 14- 8 15- 4 16- 0 16- 8 17- 4 17-11 18- 6 19- 1 19- 7 20- 2 20- 8 21- 2 21- 8 22- 2 22- 8 23- 1 23- 7 24- 0
2x10 19.2 7- 4 8- 5 9- 5 10- 4 11- 2 11-11 12- 8 13- 4 14- 0 14- 8 15- 3 15-10 16- 4 16-11
17- 5 17-11 18- 5 18-11 19- 4 19-10 20- 3 20- 8 21- 1 21- 6 21-11
24.0 6- 6 7- 7 8- 5 9- 3 10- 0 10- 8 11- 4 11-11 12- 6 13- 1 13- 7 14- 2 14- 8 15- 1 15- 7 16- 0 16- 6 16-11 17- 4 17- 9 18- 1 18- 6 18-11 19- 3 19- 7
12.0 11- 3 13- 0 14- 6 15-11 17- 2 18- 4 19- 6 20- 6 21- 7 22- 6 23- 5 24- 4 25- 2 26- 0
16.0 9- 9 11- 3 12- 7 13- 9 14-11 15-11 16-10
17- 9 18- 8 19- 6 20- 3 21- 1 21- 9 22- 6 23- 2 23-10 24- 6 25- 2 25- 9
2x12 19.2 8-11 10- 3 11- 6 12- 7 13- 7 14- 6 15- 5 16- 3 17- 0 17- 9 18- 6 19- 3 19-11 20- 6 21- 2 21- 9 22- 5 23- 0 23- 6 24- 1 24- 8 25- 2 25- 8
24.0 7-11 9- 2 10- 3 11- 3 12- 2 13- 0 13- 9 14- 6 15- 3 15-11 16- 7 17- 2 17- 9 18- 4 18-11 19- 6 20- 0 20- 6 21- 1 21- 7 22- 0 22- 6 23- 0 23- 5 23-10
E 12.0 0.11 0.17 0.23 0.31 0.38 0.47 0.56 0.66 0.76 0.86 0.97 1.09 1.21 1.33 1.46 1.59
1.72 1.86 2.00 2.14 2.29 2.44 2.60
E 16.0 0.09 0.14 0.20 0.26 0.33 0.41 0.49 0.57 0.66 0.75 0.84 0.94 1.05 1.15 1.26 1.37
1.49 1.61 1.73 1.86 1.99 2.12 2.25 2.39 2.53
E 19.2 0.09 0.13 0.18 0.24 0.30 0.37 0.44 0.52 0.60 0.68 0.77 0.86 0.95 1.05 1.15 1.25
1.36 1.47 1.58 1.70 1.81 1.93 2.05 2.18 2.31
E 24.0 0.08 0.12 0.16 0.22 0.27 0.33 0.40 0.46 0.54 0.61 0.69 0.77 0.85 0.94 1.03 1.12
1.22 1.31 1.41 1.52 1.62 1.73 1.84 1.95 2.06
Note: The required modulus of elasticity, E, in 1,000,000 pounds per square inch is shown at the bottom of each table, is limited to 2.6 million psi and less, and is applicable to all lumber sizes shown. Spans are shown in feet-inches and are limited to 26‵ and less. Check sources of supply for availability of lumber in lengths greater than 20‵.
TABLE R-11
RAFTERS WITH L/240 DEFLECTION LIMITATION
DESIGN CRITERIA:
Strength - Live Load of 40 psf plus
Dead Load of 20 psf determines the required bending design value.
Deflection - For 40 psf live load.
Note: The required modulus of elasticity, E, in 1,000,000 pounds per square inch is shown at the bottom of each table, is limited to 2.6 million psi and less, and is applicable to all lumber sizes shown. Spans are shown in feet-inches and are limited to 26‵ and less. Check sources of supply for availability of lumber in lengths greater than 20‵.
TABLE R-14
RAFTERS WITH L/180 DEFLECTION LIMITATION
DESIGN CRITERIA:
Strength - Live Load of 30 psf plus
Dead Load of 10 psf determines the required bending design value.
Deflection - For 30 psf live load.
Note: The required modulus of elasticity, E, in 1,000,000 pounds per square inch is shown at the bottom of each table, is limited to 2.6 million psi and less, and is applicable to all lumber sizes shown. Spans are shown in feet-inches and are limited to 26‵ and less. Check sources of supply for availability of lumber in lengths greater than 20‵.
TABLE R-15
RAFTERS WITH L/180 DEFLECTION LIMITATION
DESIGN CRITERIA:
Strength - Live Load of 40 psf plus
Dead Load of 10 psf determines the required bending design value.
Deflection - For 40 psf live load.
Note: The required modulus of elasticity, E, in 1,000,000 pounds per square inch is shown at the bottom of each table, is limited to 2.6 million psi and less, and is applicable to all lumber sizes shown. Spans are shown in feet-inches and are limited to 26‵ and less. Check sources of supply for availability of lumber in lengths greater than 20‵.
TABLE R-22
RAFTERS WITH L/180 DEFLECTION LIMITATION
DESIGN CRITERIA:
Strength - Live Load of 30 psf plus
Dead Load of 20 psf determines the required bending design value.
Deflection - For 30 psf live load.
Note: The required modulus of elasticity, E, in 1,000,000 pounds per square inch is shown at the bottom of each table, is limited to 2.6 million psi and less, and is applicable to all lumber sizes shown. Spans are shown in feet-inches and are limited to 26‵ and less. Check sources of supply for availability of lumber in lengths greater than 20‵.
TABLE R-23
RAFTERS WITH L/180 DEFLECTION LIMITATION
DESIGN CRITERIA:
Strength - Live Load of 40 psf plus
Dead Load of 20 psf determines the required bending design value.
Deflection - For 40 psf live load.
Note: The required modulus of elasticity, E, in 1,000,000 pounds per square inch is shown at the bottom of each table, is limited to 2.6 million psi and less, and is applicable to all lumber sizes shown. Spans are shown in feet-inches and are limited to 26‵ and less. Check sources of supply for availability of lumber in lengths greater than 20‵.
Design Values for Joists and Rafters
These “Fb" values are for use where repetitive members are spaced not more than 24 inches. Values for surfaced dry or surfaced green lumber apply at 19% maximum moisture content in use.
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See PDF for table 
321.125 (3) CONTROL STANDARDS
The following are designs acceptable by the department to achieve compliance with the control standards of acceptable soil loss or percent reduction of sediment load in runoff from a site.
Less than one acre disturbance (regardless of the lot or property size).
