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).
A. Mandated practices:
1. A method to prevent or reduce soil from leaving a site via entries or roads. This may include a tracking pad or tire washing stand designed and installed to meet DNR Standard 1057. Other means of compliance include a gravel mulch, frozen soil, bedrock or some other physical means to prevent soil from leaving the site on vehicle tires which is equivalent to the tracking pad or tire washing stand.
2. Storm water inlet protection. Inlet protection may be accomplished by using DNR Technical Standard, number 1050, “Storm Drain Inlet Protection for Construction Sites". The protection of stormwater inlets in the code is specific to “on-site" inlets; however an off-site inlet may create a direct conduit to a water of the state, which links any inlet that leads to a water of the state to the #3 mandated practice. In that case, special care should be taken to protect both types of inlets from sediment in runoff from a construction site.
3. Protection of adjoining waters of the state. The installation of practices is necessary if runoff from the disturbance could impact a water of the state. Practices may include channel erosion mats, silt fences, vegetative buffers or any other practices applicable to the specific site.
4. Drainage way protection. Any ditches or drainage ways that flow off-site must be protected with appropriate best management practices (BMPs). This may include but is not limited to ditch checks, channel erosion control mats or riprap.
