Design Value Tables
Table 1: Dimension Lumber
Table 2: Timbers
Table 3: Mechanically Graded Lumber
Table 4: Scaffold Plank
Adjustment Factors

Using Southern Pine

Design Values

Adjustment Factors

Reference design values are based on normal load duration and dry service conditions. Because the strength of wood varies with conditions under which it is used, these design values should only be applied in conjunction with appropriate design and service recommendations from the National Design Specification® (NDS®) for Wood Construction published by the American Forest & Paper Association. The latest connection design information is also provided in the NDS.

Reference design values (Fb  Ft  Fv  Fc⊥ Fc   E  Emin ) in Tables 1 thru 3 shall be multiplied by all applicable adjustment factors to determine adjusted design values (Fb´  Ft´  Fv´  Fc⊥´  Fc ´  E´  Emin´).

Table A-1 is excerpted from the NDS and summarizes the applicability of adjustment factors for solid-sawn lumber.

Table A-1 Applicability of Adjustment Factors for Sawn Lumber

Table A-1 Applicability of Adjustment Factors for Sawn Lumber
Click image to enlarge

Tables A-2 thru A-4 highlight the most common adjustment factors as they apply to Southern Pine. In addition, Table 1 and 2 footnotes provide information about the Size Factor, CF, while Tables 1 and 3 include the Repetitive Member Factor, Cr, in the tabulated Repetitive Member Use bending design values. For complete information on adjustment factors, see the NDS.

Table A-2 Wet Service Factor, CM

  • For lumber 2" to 4" thick
    Applies to all values

    When dimension lumber is used under conditions where the moisture content of the wood in service will exceed 19% for an extended time period, reference design values shall be multiplied by the appropriate wet service factors below.

Table A-2 Wet Service Factor

Table A-3 Load Duration Factor, CD

  • For all solid wood products - Allowable Stress Design
    Only Applies to Fb , Ft , Fv , and Fc values
    Does not apply to Fc⊥, E, and Emin values

  • Wood has the property of carrying substantially greater maximum loads for short durations than for long durations of loading. Reference design values apply to normal load duration, meaning a load that fully stresses a member to its allowable design value by the application of the full design load for a cumulative duration of approximately ten years. When the cumulative duration of the full maximum load does not exceed the specified time period, all reference design values (except Fc⊥, E, and Emin ) shall be multiplied by the appropriate load duration factor. Frequently used load duration factors are provided in the following table:

Load Duration
(Typical Design Loads)		 CD   Load Duration
(Typical Design Loads)		 CD
 
Permanent (dead load)
Ten years (occupancy live load)
Two months (snow load)		 0.9
1.0
1.15		   Seven days (construction load)
Ten minutes (wind/earthquake load)
Impact1 (impact load)		 1.25
1.6
2.0
  • (1) Load duration factors greater than 1.6 shall not apply to structural members pressure treated with waterborne preservatives, or fire-retardant chemicals. The impact load duration factor shall not apply to connections.

Table A-4 Flat Use Factor, Cfu

  • For lumber 2" to 4" thick
    Applies to Fb values only

    Reference bending design values, Fb, are based on edgewise use (load applied to narrow face). When dimension lumber is used flatwise (load applied to wide face), Fb shall also be multiplied by the following flat use factors:

Flat Use Factor, Cfu
Width Thickness
2" & 3" 4"
 
2" & 3"
4"
5"
6"
8"
10" and wider		 1.0
1.1
1.1
1.15
1.15
1.2		 --
1.0
1.05
1.05
1.05
1.1
Disclaimer:

Reference design values are based on normal load duration and dry service conditions. Because the strength of wood varies with conditions under which it is used, these design values should only be applied in conjunction with appropriate design and service recommendations from the National Design Specification® (NDS®) for Wood Construction published by the American Wood Council.

Southern Pine design values are published by the Southern Pine Inspection Bureau after approval by the Board of Review of the American Lumber Standard Committee. The Southern Forest Products Association does not test lumber or establish design values. Neither the Southern Forest Products Association, nor its members, warrant that the data or design values on which the recommended uses of Southern Pine lumber contained herein are based is correct, and disclaim responsibility for injury or damage resulting from the use of such design values.

The conditions under which lumber is used in construction may vary widely, as does the quality of workmanship and construction methods. Neither the Southern Forest Products Association, nor its members, have knowledge of the quality of the workmanship or construction methods used on any construction project, and, accordingly, do not warrant the design or performance of the lumber in completed structures.

About Us
Design Value Tables
Table 1: Dimension Lumber
Table 2: Timbers
Table 3: Mechanically Graded Lumber
Table 4: Scaffold Plank
Adjustment Factors

Using Southern Pine

Design Values

Adjustment Factors

Reference design values are based on normal load duration and dry service conditions. Because the strength of wood varies with conditions under which it is used, these design values should only be applied in conjunction with appropriate design and service recommendations from the National Design Specification® (NDS®) for Wood Construction published by the American Forest & Paper Association. The latest connection design information is also provided in the NDS.

Reference design values (Fb  Ft  Fv  Fc⊥ Fc   E  Emin ) in Tables 1 thru 3 shall be multiplied by all applicable adjustment factors to determine adjusted design values (Fb´  Ft´  Fv´  Fc⊥´  Fc ´  E´  Emin´).

Table A-1 is excerpted from the NDS and summarizes the applicability of adjustment factors for solid-sawn lumber.

Table A-1 Applicability of Adjustment Factors for Sawn Lumber

Table A-1 Applicability of Adjustment Factors for Sawn Lumber
Click image to enlarge

Tables A-2 thru A-4 highlight the most common adjustment factors as they apply to Southern Pine. In addition, Table 1 and 2 footnotes provide information about the Size Factor, CF, while Tables 1 and 3 include the Repetitive Member Factor, Cr, in the tabulated Repetitive Member Use bending design values. For complete information on adjustment factors, see the NDS.

Table A-2 Wet Service Factor, CM

Table A-2 Wet Service Factor

Table A-3 Load Duration Factor, CD

Load Duration
(Typical Design Loads)		 CD   Load Duration
(Typical Design Loads)		 CD
 
Permanent (dead load)
Ten years (occupancy live load)
Two months (snow load)		 0.9
1.0
1.15		   Seven days (construction load)
Ten minutes (wind/earthquake load)
Impact1 (impact load)		 1.25
1.6
2.0

Table A-4 Flat Use Factor, Cfu

Flat Use Factor, Cfu
Width Thickness
2" & 3" 4"
 
2" & 3"
4"
5"
6"
8"
10" and wider		 1.0
1.1
1.1
1.15
1.15
1.2		 --
1.0
1.05
1.05
1.05
1.1
Disclaimer:

Reference design values are based on normal load duration and dry service conditions. Because the strength of wood varies with conditions under which it is used, these design values should only be applied in conjunction with appropriate design and service recommendations from the National Design Specification® (NDS®) for Wood Construction published by the American Wood Council.

Southern Pine design values are published by the Southern Pine Inspection Bureau after approval by the Board of Review of the American Lumber Standard Committee. The Southern Forest Products Association does not test lumber or establish design values. Neither the Southern Forest Products Association, nor its members, warrant that the data or design values on which the recommended uses of Southern Pine lumber contained herein are based is correct, and disclaim responsibility for injury or damage resulting from the use of such design values.

The conditions under which lumber is used in construction may vary widely, as does the quality of workmanship and construction methods. Neither the Southern Forest Products Association, nor its members, have knowledge of the quality of the workmanship or construction methods used on any construction project, and, accordingly, do not warrant the design or performance of the lumber in completed structures.