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Chapter 3 — Wood: Appendix

Table A-3.1: Design values for tension, Ft (psi) for visually graded lumber and glued-laminated timber

A. Dimension lumber (2 in. – 4 in. thick)
SpeciesSelect StructuralNo. 1No. 2No. 3Miscellaneous
Douglas Fir-Larch10006755753251800
Douglas Fir-Larch (North)825n/an/a3002500
Douglas Fir-South900600525300 
Hem-Fir9256255253001725
Hem-Fir (North)775n/an/a3252575
Spruce-Pine-Fir700n/an/a2502450
Spruce-Pine-Fir (South)575400350200 
Southern Pine31000650525300 
B. Beams and stringers4
SpeciesSelect StructuralNo. 1No. 2No. 3Miscellaneous
Douglas Fir-Larch950675425n/a 
Douglas Fir-Larch (North)950675425n/a 
Douglas Fir-South900625425n/a 
Hem-Fir750525350n/a 
Hem-Fir (North)725500325n/a 
Spruce-Pine-Fir650450300n/a 
Spruce-Pine-Fir (South)625450300n/a 
Southern Pine51000900550n/a 
C. Posts and timbers6
SpeciesSelect StructuralNo. 1No. 2No. 3Miscellaneous
Douglas Fir-Larch1000825475n/a 
Douglas Fir-Larch (North)1000825475n/a 
Douglas Fir-South950775450n/a 
Hem-Fir800650375n/a 
Hem-Fir (North)775625375n/a 
Spruce-Pine-Fir700550325n/a 
Spruce-Pine-Fir (South)675550325n/a 
Southern Pine51000900550n/a 
D. Glued-laminated softwood timber
SpeciesGrade (and Identification No.)
Douglas Fir-Larch (DF) L3 (ID#1)
950
L2 (ID#2)
1250
L2D (ID#3)
1450
L1D L1 (ID#5)
1650
Softwood Species (SW)L3 (ID#22) 525
Alaska Cedar (AC) L3 (ID#69)
725
L2 (ID#70)
975
L1D (ID#71)
1250
L1S (ID#72)
1250
Southern Pine (SP) N2M14 N2M12
(ID#47) 1200
N2D14 N2D12
(ID#48) 1400
N1M16 (ID#49)
1350
N1D14 (ID#50)
1550

Notes:

1. No.1 & better

2. No.1/No.2

3. Values for Southern Pine for dimension lumber are approximate: typical published values include the size factor and therefore list different values for each lumber width; whereas the values in this table have been normalized (i.e., do not include the size factor) and have been rounded down to values that may be slightly conservative.

4. Beams and stringers are a subset of the "timbers" size category, 5 in. × 5 in. or larger, where the width is at least 4 in. bigger than the thickness.

5. Southern Pine values for timbers (beams and stringers; and posts and timbers) are for wet service conditions.

6. Posts and timbers are a subset of the "timbers" size category, 5 in. × 5 in. or larger, where the width is equal to, or no more than 2 in. bigger than, the thickness.


Table A-3.2: Adjustments to allowable stress in tension, Ft, for visually-graded lumber and glued-laminated softwood timber

A. Size factor
Size factor, CF = 1.0 for tension stress, except for the following sizes of dimension lumber:
Size
CF
Size
CF
Size
CF
Size
CF
22 × 2
1.5
42 × 8
1.2
1,42 × 14, 4 × 14
0.9
44 × 8
1.2
22 × 4
1.5
42 × 10
1.1
24 × 4
1.5
44 × 10
1.1
32 × 6
1.3
42 × 12
1.0
34 × 6
1.3
44 × 12
1.0
B. Wet service factor
Wet service factor, CM = 1.0, except for glulam with a moisture content of at least 16% (e.g., used outdoors), in which case CM = 0.8. In any dry service condition, CM = 1.0.
C. Load duration factor
Load duration factor, CD, is as follows:
Load type
Duration
CD
Load type
Duration
CD
Dead load, D
Permanent
0.90
Construction load, Lr
1 week
1.25
Live load, L
10 years
1.00
Wind or seismic load, W or E
10 minutes
1.60
Snow load, S
2 months
1.15
Impact load, I
instant
2.00
D. Temperature factor, Ct
Temperature, T, (°F)Ct
T ≤ 100°F1.0
100°F < T ≤ 150°F0.9

Notes:

1. CF = 0.9 for all 2× or 4× dimension lumber having nominal width greater or equal to 14.

2. Exceptions: CF = 1.1 for stud grade 2 × 2, 2 × 4, and 4 × 4 lumber; CF = 1.0 for construction and standard 2 × 2, 2 × 4, and 4 × 4 lumber; and CF = 0.4 for utility grade 2 × 2 lumber

3. Exceptions: CF = 1.0 for stud grade 2 × 6 and 4 × 6 lumber

4. Exceptions: For stud grade lumber with nominal width of 8 or higher, use No.3 grade values for Ft and CF


Table A-3.3: Design values for compression (psi), parallel to grain (Fc) and perpendicular to grain (Fc-per) for visually-graded lumber and glued-laminated softwood timber timber

A. Dimension lumber (2 in. – 4 in. thick)
SpeciesFc
(parallel to grain)
Fc-per
(perpendicular to grain)
Select StructuralNo. 1No. 2No. 3Misc.All grades7
Douglas Fir-Larch17001500135077511550625
Douglas Fir-Larch (North)1900n/an/a82521400625
Douglas Fir-South160014501450775 520
Hem-Fir15001350130072511350405
Hem-Fir (North)1700n/an/a85021450405
Spruce-Pine-Fir1400n/an/a65021150425
Spruce-Pine-Fir (South)120010501000575 335
Southern Pine3180015751425825 565
B. Beams and stringers4
SpeciesFc
(parallel to grain)
Fc-per
(perpendicular to grain)
Select StructuralNo. 1No. 2No. 3Misc.All grades7
Douglas Fir-Larch1100925600n/a 625
Douglas Fir-Larch (North)1100925600n/a 625
Douglas Fir-South1000850550n/a 520
Hem-Fir925750500n/a 405
Hem-Fir (North)900750475n/a 405
Spruce-Pine-Fir775625425n/a 425
Spruce-Pine-Fir (South)675550375n/a 335
Southern Pine5950825525n/a 375
C. Posts and timbers4
SpeciesFc
(parallel to grain)
Fc-per
(perpendicular to grain)
Select StructuralNo. 1No. 2No. 3Misc.All grades7
Douglas Fir-Larch11501000700n/a 625
Douglas Fir-Larch (North)11501000700n/a 625
Douglas Fir-South1050925650n/a 520
Hem-Fir975850575n/a 405
Hem-Fir (North)950850575n/a 405
Spruce-Pine-Fir800700500n/a 425
Spruce-Pine-Fir (South)700625425n/a 335
Southern Pine5950825525n/a 375
D. Glued-laminated softwood timber
SpeciesGrade (and Identification No.)
Fc (parallel to grain)Fc-per (perpendicular to grain)
 
 
Douglas Fir-Larch8 (DF)
(less than 4 laminations)
L3
(ID#1)

1550
1250
L2
(ID#2)

1950
1600
L2D
(ID#3)

2300
1900
L1
(ID#5)

2400
2100
L3
(ID#1)

560
560
L2
(ID#2)

560
560
L2D
(ID#3)

650
650
L1
(ID#5)

650
650
 
Softwood Species8 (SW)
(less than 4 laminations)
L3 (ID#22)
850
525
L3 (ID#22)
315
315
 
 
Alaska Cedar8 (AC)
(less than 4 laminations)
L3
(ID#69)

1150
1100
L2
(ID#70)

1450
1450
L1D
(ID#71)

1900
1900
L1S
(ID#72)

1900
1900
L3
(ID#69)

470
470
L2
(ID#70)

470
470
L1D
(ID#71)

560
560
L1S
(ID#72)

560
560
 
 
Southern Pine8 (SP)
(less than 4 laminations)
N2M12
(ID#47)

1900
1150
N2D12
(ID#48)

2200
1350
N1M16
(ID#49)

2100
1450
N1D14
(ID#50)

2300
1700
N2M12
(ID#47)

650
650
N2D12
(ID#48)

740
740
N1M16
(ID#49)

650
650
N1D14
(ID#50)

740
740

Notes:

1. No.1 & better

2. No.1/No.2

3. Values for Southern Pine for dimension lumber are approximate: typical published values include the size factor and therefore list different values for each lumber width; whereas the values in this table have been normalized (i.e., do not include the size factor) and have been rounded down to values that may be slightly conservative.

4. Beams and stringers are a subset of the "timbers" size category, 5 in. × 5 in. or larger, where the width is at least 4 in. bigger than the thickness.

5. Southern Pine values for timbers (beams and stringers; posts and timbers) are for wet service conditions.

6. Posts and timbers are a subset of the "timbers" size category, 5 in. × 5 in. or larger, where the width is equal to, or no more than 2 in. bigger than, the thickness.

7. Values for compression perpendicular to grain apply to all the size categories listed in this table (i.e., listed under compression parallel to grain). However, "dense" variations of Douglas Fir-Larch and Southern Pine, not listed here, have higher values.

8. These species designations are designed primarily for axially-loaded elements (compression and tension).

9. These combination designations are designed primarily for bending elements, although they can be used in axial compression or tension with the values that appear in this table. Values for Fc-per (compression perpendicular to grain) are based on loading perpendicular to the wide face of the laminations.


Table A-3.4: Adjustments to allowable stress in compression, Fc, for visually-graded lumber and glued-laminated softwood timber

A. Size factor
Size factor, CF = 1.0 for compression stress, except for the following sizes of dimension lumber:
Size
CF
Size
CF
Size
CF
Size
CF
62 × 2
1.15
82 × 8
1.05
1,82 × 14, 4 × 14
0.9
84 × 8
1.05
62 × 4
1.15
82 × 10
1.00
64 × 4
1.15
84 × 10
1.00
72 × 6
1.10
82 × 12
1.00
74 × 6
1.10
84 × 12
1.00
B. Wet service factor
Wet service factor, CM, is as follows: for dimension lumber2, CM = 0.8; for timbers, CM = 0.91; for glulam, CM = 0.73. In any dry service condition, CM = 1.0.
C. Load duration factor
Load duration factor, CD, is as follows:
Load type
Duration
CD
Load type
Duration
CD
Dead load, D
Permanent
0.90
Construction load, Lr
1 week
1.25
Live load, L
10 years
1.00
Wind or seismic load, W or E
10 minutes
1.60
Snow load, S
2 months
1.15
Impact load, I
instant
2.00
D. Column stability factor5
The column stability factor, Cp, is as follows: Cp = Aequation
where:
equation
E'min = EminCM (see Appendix Table A-3.9 for adjustments to E and Emin)
 
  d = cross-sectional dimension (in.) corresponding to the unbraced length, le. Where the unbraced length is the same for both axes of the cross section, d should be taken as the smaller cross-sectional dimension; otherwise, use the larger value of le/d
 
  le = the unbraced length corresponding to the cross-sectional dimension, d
 
  c = 0.8 for sawn lumber, and 0.9 for glulam
E. Temperature factor, Ct
Temperature, T, (°F)Ct (used dry)Ct (used wet)
T ≤ 100°F1.01.0
100°F < T ≤ 125°F0.80.7
125°F < T ≤ 150°F0.70.5

Notes:

1. CF = 0.9 for all 2× or 4× dimension lumber having nominal width greater or equal to 14.

2. CM = 1.0 for dimension lumber when FcCF ≤ 750 psi.

3. Size factor adjustments are not used for compression perpendicular to grain.

4. Load duration adjustments are not used for compression perpendicular to grain.

5. Column stability factor adjustments are not used for compression perpendicular to grain.

6. Exceptions: CF = 1.05 for stud grade 2 × 2, 2 × 4, and 4 × 4 lumber; CF = 1.0 for construction and standard 2 × 2, 2 × 4, and 4 × 4 lumber; and CF = 0.6 for utility grade 2 × 2 lumber

7. Exceptions: CF = 1.0 for stud grade 2 × 6 and 4 × 6 lumber

8. Exceptions: For stud grade lumber with nominal width of 8 or higher, use No.3 grade values for Fc and CF


Table A-3.5: Design values for bending, Fb (psi) for visually-graded lumber and glued-laminated softwood timber timber

A. Dimension lumber (2 in. – 4 in. thick)
SpeciesSelect StructuralNo. 1No. 2No. 3Miscellaneous
Douglas Fir-Larch1500100090052511200
Douglas Fir-Larch (North)1350n/an/a4752850
Douglas Fir-South1350925850500 
Hem-Fir140097585050011100
Hem-Fir (North)1300n/an/a57521000
Spruce-Pine-Fir1250n/an/a5002875
Spruce-Pine-Fir (South)1300875775450 
Southern Pine318501175950550 
B. Beams and stringers4
SpeciesSelect StructuralNo. 1No. 2No. 3Miscellaneous
Douglas Fir-Larch16001350875n/a 
Douglas Fir-Larch (North)16001300875n/a 
Douglas Fir-South15501300825n/a 
Hem-Fir13001050765n/a 
Hem-Fir (North)12501000675n/a 
Spruce-Pine-Fir1100900600n/a 
Spruce-Pine-Fir (South)1050900575n/a 
Southern Pine515001350850n/a 
C. Posts and timbers6
SpeciesSelect StructuralNo. 1No. 2No. 3Miscellaneous
Douglas Fir-Larch15001200750n/a 
Douglas Fir-Larch (North)15001200725n/a 
Douglas Fir-South14501150675n/a 
Hem-Fir1200975575n/a 
Hem-Fir (North)1150925550n/a 
Spruce-Pine-Fir1050850500n/a 
Spruce-Pine-Fir (South)1000800475n/a 
Southern Pine515001350850n/a 
D. Glued-laminated softwood timber
SpeciesGrade (and Identification No.)
Fb (for beams with d > 15 in.)Fb (for beams with d ≤ 15 in.)
 
 
Douglas Fir-Larch7 (DF)
L3
(ID#1)

1100
L2
(ID#2)

1496
L2D
(ID#3)

1760
L1
(ID#5)

1936
L3
(ID#1)

1250
L2
(ID#2)

1700
L2D
(ID#3)

2000
L1
(ID#5)

2200
 
Softwood Species7 (SW)
L3 (ID#22)
638
L3 (ID#22)
725
 
 
Alaska Cedar7 (AC)
L3
(ID#69)

880
L2
(ID#70)

1188
L1D
(ID#71)

1540
L1S
(ID#72)

1672
L3
(ID#69)

1000
L2
(ID#70)

1350
L1D
(ID#71)

1750
L1S
(ID#72)

1900
 
 
Southern Pine7 (SP)
N2M12
(ID#47)

1232
N2D12
(ID#48)

1408
N1M16
(ID#49)

1584
N1D14
(ID#50)

1848
N2M12
(ID#47)

1400
N2D12
(ID#48)

1600
N1M16
(ID#49)

1800
N1D14
(ID#50)

2100
Various species8 (SP) Combination Symbols for Stress Classes
Fb (for positive bending9) Fb (for negative bending9)
16F-1.3E
1600
20F-1.5E
2000
24F-1.7E
2400
24F-1.8E
2400
16F-1.3E
925
20F-1.5E
1100
24F-1.7E
1450
24F-1.8E
1450
E. Glued-laminated softwood timber bent about y-axis (loaded parallel to wide face of laminations)
SpeciesGrade (and Identification No.)
Fb (for 4 or more laminations)Fb (for 3 laminations)
 
 
Douglas Fir-Larch7 (DF)
L3
(ID#1)

1450
L2
(ID#2)

1800
L2D
(ID#3)

2100
L1
(ID#5)

2400
L3
(ID#1)

1250
L2
(ID#2)

1600
L2D
(ID#3)

1850
L1
(ID#5)

2100
 
Softwood Species7 (SW)
L3 (ID#22)
800
L3 (ID#22)
700
 
 
Alaska Cedar7 (AC)
L3
(ID#69)

1100
L2
(ID#70)

1400
L1D
(ID#71)

1850
L1S
(ID#72)

1850
L3
(ID#69)

975
L2
(ID#70)

1250
L1D
(ID#71)

1650
L1S
(ID#72)

1650
 
 
Southern Pine7 (SP)
N2M12
(ID#47)

1750
N2D12
(ID#48)

2000
N1M16
(ID#49)

1950
N1D14
(ID#50)

2300
N2M12
(ID#47)

1550
N2D12
(ID#48)

1800
N1M16
(ID#49)

1750
N1D14
(ID#50)

2100
Various species8 (SP) Combination Symbols for Stress Classes
Fb (all cases)
16F-1.3E
800
20F-1.5E
800
24F-1.7E
1050
24F-1.8E
1450

Notes:

1. No.1 & better

2. No.1/No.2

3. Values for Southern Pine for dimension lumber are approximate: typical published values include the size factor and therefore list different values for each lumber width; whereas the values in this table have been normalized (i.e., do not include the size factor) and have been rounded down to values that may be slightly conservative.

4. Beams and stringers are a subset of the "timbers" size category, 5 in. × 5 in. or larger, where the width is at least 4 in. bigger than the thickness.

5. Southern Pine values for timbers (beams and stringers; posts and timbers) are for wet service conditions.

6. Posts and timbers are a subset of the "timbers" size category, 5 in. × 5 in. or larger, where the width is equal to, or no more than 2 in. bigger than, the thickness.

7. These species designations are designed primarily for axially-loaded elements (compression and tension), although they can be used for bending with the values that appear in this table. For bending about the x-axis only, these elements are assumed to have no special tension laminations; such special tension laminations would increase the bending design values (for all cross-section sizes bent about the x-axis) to the values shown for d ≤ 15 in. multiplied by a factor of 1.18.

8. These combination designations are designed primarily for simply-supported bending elements (i.e., for beams with only positive bending moments), and are manufactured with higher strength grades of wood used in the extreme fibers (for bending about the x-axis) where bending stresses are greatest.

9. The combination symbols in this table refer to cross sections that are "unbalanced"; i.e., they are manufactured to optimize the behavior of simply-supported beams with only positive curvature. Where such unbalanced combinations are used for beams subjected to negative bending moments — i.e., for continuous or cantilevered beams — lower values for Fb must be used at those cross sections with negative moment. For beams subjected to reversals of curvature (and therefore both positive and negative bending), "balanced" (symmetrical) combinations can be specified where Fb is the same for both positive and negative bending, for example: combination symbols 16F-V6 with Fb = 1600 psi; 20F-V7 with Fb = 2000 psi; and 24F-V8 with Fb = 2400 psi.


Table A-3.6: Adjustments to allowable stress in bending, Fb, for visually-graded lumber and glued-laminated softwood timber

A. Size factor3
Size factor, CF. (1) For glulam, size factor does not apply (use smaller of CV and CL — see Table A-3.6 Parts C and F below). (2) For timbers (beams and stringers; posts and timbers): when d > 12 in., CF = (12/d)1/9 ≤ 1; when loaded on the wide face, CF = 0.86 (select structural), 0.74 (No.1), or 1.00 (No.2); otherwise, CF = 1.00. (3) For dimension lumber, CF is as shown here:
Size
CF
Size
CF
Size
CF
Size
CF
32 × 2
1.5
52 × 8
1.2
1,52 × 14
0.9
54 × 8
1.3
32 × 4
1.5
52 × 10
1.1
34 × 4
1.5
54 × 10
1.2
42 × 6
1.3
1,52 × 12, 4 × 14
1.0
44 × 6
1.3
1,54 × 12
1.1
B. Flat use factor
Flat use factor, Cfu, is used only when dimension lumber (or glulam) is oriented about its weak axis:
(1) For dimension lumber:
Size
Cfu
Size
Cfu
Size
Cfu
Size
Cfu
2 × 4
1.10
2 × 10
1.20
4 × 6
1.05
4 × 12
1.10
2 × 6
1.15
2 × 12
1.20
4 × 8
1.05
4 × 14
1.10
2 × 8
1.15
2 × 14
1.20
4 × 10
1.10
4 × 16
1.10
(2) For glulam:
For glulam beams bent about their weak (y) axis, and where the depth, d < 12 in.:
 
Cfu = (12/d)1/9
 

 
The approximate values shown below can be used as an alternative:
glulam used flat
Depth, d (in.)
Cfu
Depth, d (in.)
Cfu
2-1/2
1.19
6-3/4
1.07
3 or 3-1/8
1.16
8-1/2 or 8-3/4
1.04
5 or 5-1/8
1.10
10-1/2 or 10-3/4
1.01
C. Volume factor
The volume factor, CV, is used only for glulam beams loaded about their strong axes, and only if smaller than CL (see below). For these conditions:
 
equation
 
where
  L = the length of the simply-supported beam, or, for other beam types the distance between points of zero moment (ft)
  d = beam depth (in.)
  b = beam width (in.)
  x = 10 (except x = 20 for Southern Pine only)
D. Wet service factor
Wet service factor, CM, is as follows: for 2dimension lumber, CM = 0.85; for timbers, CM = 1.0; for glulam, CM = 0.8. In any dry service condition, CM = 1.0.
E. Repetitive member factor
Repetitive member factor, Cr = 1.15, is used only for dimension lumber spaced 24 in. on center or less (typically the case with joists and rafters).
F. Beam stability factor
The beam stability factor, CL, may apply to glulam and timber beams, but not ordinarily to dimension lumber, and only when the compression edge of the beam is unbraced by a roof or floor deck. For continuously braced beams, i.e., when le = 0, CL = 0. For glulam, use only the smaller value of CL or CV. For timbers, combine CL with the size factor, CF. Use only when the beam depth is greater than its width. For these conditions, the beam stability factor, CL, is as follows: CL = Aequation
where:
 
equation
 
E'min = EminCM (see Appendix Table A-3.9 for adjustments to E and Emin)
d = beam depth (in.) and b = beam width (in.)
lu = the unsupported (unbraced) length (in.), i.e., the greatest distance between lateral braces, including bridging or blocking, along the length of the beam
le = the effective unsupported length (in.) where continuous lateral support is not provided as shown in these selected loading patterns:
Load arrangement
Effective length, le
Load arrangement
Effective length, le
equation
Uniform load: no lateral
support except at ends.
le = 1.63lu + 3d for lu/d ≥ 7
 
 
le = 2.06lu for lu/d < 7
equation
Concentrated loads at third points:
lateral support under loads and ends only.
 
 
 
le = 1.68lu
equation
Single concentrated load at midspan:
no lateral support except at ends.
le = 1.80lu for lu/d < 7
 
 
le = 1.37lu + 3d for lu/d ≥ 7
 
 
 
equation
Concentrated loads at quarter points:
lateral support under loads and ends only.
 
 
 
 
 
 
le = 1.54lu
equation
Single concentrated load at midspan:
lateral support under load and ends only.
 
 
 
le
= 1.11lu
G. Load duration factor
Load duration factor, CD, is as follows:
Load type
Duration
CD
Load type
Duration
CD
Dead load, D
Permanent
0.90
Construction load, Lr
1 week
1.25
Live load, L
10 years
1.00
Wind or seismic load, W or E
10 minutes
1.60
Snow load, S
2 months
1.15
Impact load, I
instant
2.00
H. Temperature factor, Ct
Temperature, T, (°F)Ct (used dry)Ct (used wet)
T ≤ 100°F1.01.0
100°F < T ≤ 125°F0.80.7
125°F < T ≤ 150°F0.70.5

Notes:

1. CF = 0.9 for all 2× dimension lumber having nominal width greater or equal to 14. CF = 1.0 for all 4× dimension lumber having nominal width greater or equal to 14.

2. CM = 1.0 for dimension lumber when FbCF ≤ 1150 psi.

3. Exceptions: CF = 1.1 for stud grade 2 × 2, 2 × 4, and 4 × 4 lumber; CF = 1.0 for construction and standard 2 × 2, 2 × 4, and 4 × 4 lumber; and CF = 0.4 for utility grade 2 × 2 lumber

4. Exceptions: CF = 1.0 for stud grade 2 × 6 and 4 × 6 lumber

5. Exceptions: For stud grade lumber with nominal width of 8 in. or higher, use No.3 grade values for Fb and CF


Table A-3.7: Design values for shear, Fv (psi) for visually-graded lumber and glued-laminated softwood timber timber

A. Dimension lumber (2 in. – 4 in. thick)
SpeciesSelect StructuralNo. 1No. 2No. 3Miscellaneous
Douglas Fir-Larch1801801801801180
Douglas Fir-Larch (North)180n/an/a1802180
Douglas Fir-South180180180180 
Hem-Fir1501501501501150
Hem-Fir (North)145n/an/a1452145
Spruce-Pine-Fir135n/an/a1352135
Spruce-Pine-Fir (South)135135135135 
Southern Pine3175175175175 
B. Timbers3
SpeciesSelect StructuralNo. 1No. 2No. 3Miscellaneous
Douglas Fir-Larch170170170n/a 
Douglas Fir-Larch (North)170170170n/a 
Douglas Fir-South165165165n/a 
Hem-Fir140140140n/a 
Hem-Fir (North)135135135n/a 
Spruce-Pine-Fir125125125n/a 
Spruce-Pine-Fir (South)125125125n/a 
Southern Pine5165165165n/a 
C. Glued-laminated softwood timber bent about x-axis (loaded perpendicular to wide face of laminations)
SpeciesGrade (and Identification No.)
Fv (for bending about x-axis7)
 
 
Douglas Fir-Larch5 (DF)
L3
(ID#1)

265
L2
(ID#2)

265
L2D
(ID#3)

265
L1D L1
(ID#5)

265
 
Softwood Species5,8 (SW)
L3 (ID#22)
195
 
 
Alaska Cedar5 (AC)
L3
(ID#69)

265
L2
(ID#70)

265
L1D
(ID#71)

265
L1S
(ID#72)

265
 
 
Southern Pine5 (SP)
N2M14 N2M12
(ID#47)

300
N2D14 N2D12
(ID#48)

300
N1M16
(ID#49)

300
N1D14
(ID#50)

300
Species Combination Symbols for Stress Classes
Fv (for bending about x-axis7)
 
Various species6
16F-1.3E
195
20F-1.5E
195
24F-1.7E
210
24F-1.8E
265
D. Glued-laminated softwood timber bent about y-axis (loaded parallel to wide face of laminations)
SpeciesGrade (and Identification No.)
Fv (for bending about x-axis7)
 
 
Douglas Fir-Larch5 (DF)
L3
(ID#1)

230
L2
(ID#2)

230
L2D
(ID#3)

230
L1D L1
(ID#5)

230
 
Softwood Species5,8 (SW)
L3 (ID#22)
170
 
 
Alaska Cedar5 (AC)
L3
(ID#69)

230
L2
(ID#70)

230
L1D
(ID#71)

230
L1S
(ID#72)

230
 
 
Southern Pine5 (SP)
N2M14 N2M12
(ID#47)

260
N2D14 N2D12
(ID#48)

260
N1M16
(ID#49)

260
N1D14
(ID#50)

260
Species Combination Symbols for Stress Classes
Fv (for bending about x-axis7)
 
Various species6
16F-1.3E
170
20F-1.5E
170
24F-1.7E
185
24F-1.8E
230

Notes:

1. No.1 & better

2. No.1/No.2

3. Timbers include "beams and stringers" and "posts and timbers," i.e., all cross sections 5 in. × 5 in. or larger.

4. Southern Pine values for timbers (beams and stringers; and posts and timbers) are for wet service conditions.

5. These species designations are designed primarily for axially-loaded elements (compression and tension), although they can be used for bending with the shear values that appear in this table.

6. These combination designations are designed primarily for bending elements, and are manufactured with higher strength grades of wood used in the extreme fibers where bending stresses are greatest when bent about the x-axis.

7. These values for horizontal shear must be reduced by a factor of 0.72 when used in the design of mechanical connections.

8. The design values for Fv shown for "softwood species" must be reduced by 10 psi (before adjustments are considered) when the following species are used in combination: Coast Sitka Spruce, Coast Species, Western White Pine, and Eastern White Pine.


Table A-3.8: Adjustments to allowable stress in shear, Fv, for visually-graded lumber and glued-laminated softwood timber

A. Wet service factor
Wet service factor, CM is as follows: for dimension lumber, CM = 0.97; for timbers, CM = 1.0; for glulam, CM = 0.875. In any dry service condition, CM = 1.0.
B. Load duration factor
Load duration factor, CD, is as follows:
Load type
Duration
CD
Load type
Duration
CD
Dead load, D
Permanent
0.90
Construction load, Lr
1 week
1.25
Live load, L
10 years
1.00
Wind or seismic load, W or E
10 minutes
1.60
Snow load, S
2 months
1.15
Impact load, I
instant
2.00
C. Temperature factor, Ct
Temperature, T, (°F)Ct (used dry)Ct (used wet)
T ≤ 100°F1.01.0
100°F < T ≤ 125°F0.80.7
125°F < T ≤ 150°F0.70.5


Table A-3.9: Design values for modulus of elasticity, E and Emin (psi) for visually graded lumber and glued-laminated timber (values and adjustments)

A. Modulus of elasticity, E (psi)5
Dimension lumber
(2 in. – 4 in. thick)
Select StructuralNo. 1No. 2No. 3Miscellaneous
Douglas Fir-Larch1,900,0001,700,0001,600,0001,400,00011,800,000
Douglas Fir-Larch (North)1,900,000n/an/a1,400,00021,600,000
Douglas Fir-South1,400,0001,300,0001,200,0001,100,000 
Hem-Fir1,600,0001,500,0001,300,0001,200,00011,500,000
Hem-Fir (North)1,700,000n/an/a1,400,00021,600,000
Spruce-Pine-Fir1,500,000n/an/a1,200,00021,400,000
Spruce-Pine-Fir (South)1,300,0001,200,0001,100,0001,000,000 
Southern Pine1,800,0001,700,0001,600,0001,400,000 
Timbers3Select StructuralNo. 1No. 2No. 3Miscellaneous
Douglas Fir-Larch1,600,0001,600,0001,300,000n/a 
Douglas Fir-Larch (North)1,600,0001,600,0001,300,000n/a 
Douglas Fir-South1,200,0001,200,0001,100,000n/a 
Hem-Fir1,300,0001,300,0001,100,000n/a 
Hem-Fir (North)1,300,0001,300,0001,100,000n/a 
Spruce-Pine-Fir1,300,0001,300,0001,100,000n/a 
Spruce-Pine-Fir (South)1,200,0001,200,0001,000,000n/a 
Southern Pine1,500,0001,500,0001,200,000n/a 
Glued-Laminated
Software Timber
Grade (and Identification No.)
 
 
Douglas Fir-Larch7 (DF)
L3
(ID#1)

1,500,000
L2
(ID#2)

1,600,000
L2D
(ID#3)

1,900,000
L1
(ID#5)

2,000,000
 
Softwood Species7,9 (SW)
L3 (ID#22)
1,000,000
 
 
Alaska Cedar7 (AC)
L3
(ID#69)

1,400,000
L2
(ID#70)

1,700,000
L1D
(ID#71)

1,700,000
L1S
(ID#72)

1,900,000
 
 
Southern Pine7 (SP)
N2M12
(ID#47)

1,400,000
N2D12
(ID#48)

1,700,000
N1M16
(ID#49)

1,700,000
N1D14
(ID#50)

1,900,000
  Combination Symbols for Stress Classes
Various species (bending about x-axis)8 16F-1.3E
1,300,000
20F-1.5E
1,500,000
24F-1.7E
1,700,000
24F-1.8E
1,800,000
Various species (bending about y-axis)8 16F-1.3E
1,100,000
20F-1.5E
1,200,000
24F-1.7E
1,300,000
24F-1.8E
1,600,000
B. Modulus of elasticity, Emin (psi)6
Dimension lumber
(2 in. – 4 in. thick)
Select StructuralNo. 1No. 2No. 3Miscellaneous
Douglas Fir-Larch690,000620,000580,000510,0001660,000
Douglas Fir-Larch (North)690,000n/an/a510,0002580,000
Douglas Fir-South510,000470,000440,000400,000 
Hem-Fir580,000550,000470,000440,0001550,000
Hem-Fir (North)620,000n/an/a510,0002580,000
Spruce-Pine-Fir550,000n/an/a440,0002510,000
Spruce-Pine-Fir (South)470,000440,000400,000370,000 
Southern Pine660,000620,000580,000510,000 
Timbers3Select StructuralNo. 1No. 2No. 3Miscellaneous
Douglas Fir-Larch580,000580,000470,000n/a 
Douglas Fir-Larch (North)580,000580,000470,000n/a 
Douglas Fir-South440,000440,000370,000n/a 
Hem-Fir470,000470,000400,000n/a 
Hem-Fir (North)470,000470,000400,000n/a 
Spruce-Pine-Fir470,000470,000370,000n/a 
Spruce-Pine-Fir (South)440,000440,000370,000n/a 
Southern Pine550,000550,000440,000n/a 
Glued-Laminated
Software Timber
Grade (and Identification No.)
 
 
Douglas Fir-Larch7 (DF)
L3
(ID#1)

790,000
L2
(ID#2)

850,000
L2D
(ID#3)

1,000,000
L1
(ID#5)

1,060,000
 
Softwood Species7,9 (SW)
L3 (ID#22)
530,000
 
 
Alaska Cedar7 (AC)
L3
(ID#69)

630,000
L2
(ID#70)

690,000
L1D
(ID#71)

850,000
L1S
(ID#72)

850,000
 
 
Southern Pine7 (SP)
N2M12
(ID#47)

740,000
N2D12
(ID#48)

900,000
N1M16
(ID#49)

900,000
N1D14
(ID#50)

1,000,000
  Combination Symbols for Stress Classes
Various species (bending about x-axis)8 16F-1.3E
690,000
20F-1.5E
790,000
24F-1.7E
900,000
24F-1.8E
1,000,000
Various species (bending about y-axis)8 16F-1.3E
580,000
20F-1.5E
630,000
24F-1.7E
690,000
24F-1.8E
850,000
C. Wet service adjustment (CM) to E and Emin
Wet service factor, where applicable, is as follows: for dimension lumber, CM = 0.9; for glulam, CM = 0.833; for any other condition, CM = 1.0. In any dry service condition, CM = 1.0.
D. Temperature factor adjustment (Ct) to E and Emin
Temperature, T, (°F)Ct
T ≤ 100°F1.0
100°F < T ≤ 150°F0.9

Notes:

1. No.1 & better

2. No.1/No.2

3. Timbers include "beams and stringers" and "posts and timbers," i.e., all cross sections 5 in. × 5 in. or larger.

4. Southern Pine values for timbers (beams and stringers; and posts and timbers) are for wet service conditions.

5. The modulus of elasticity, E, is an average value, used in the calculation of beam deflections, but not for column or beam stability calculations.

6. The minimum modulus of elasticity, Emin, is a conservative (low) value, based on statistical analyses of moduli for tested samples, and is used in calculations of column buckling (CP) and beam stability (CL).

7. These species designations are designed primarily for axially-loaded elements (compression and tension), although they can be used in any context with the values that appear in this table.

8. These combination designations are designed primarily for bending elements, although they can be used in any context with the values that appear in this table.

9. The design values for E shown for "softwood species" must be reduced from 1,000,000 psi to 900,000 psi when the following species are used in combination: Western Cedars, Western Cedars (North), Western Woods, and Redwood (open grain).

10. The design values for Emin shown for "softwood species" must be reduced from 530,000 psi to 477,200 psi when the following species are used in combination: Western Cedars, Western Cedars (North), Western Woods, and Redwood (open grain).


Table A-3.10: Use of load duration factor, CD, for wood elements

Where more than one load type acts on a wood structural element, CD corresponds to the load of shortest duration. Values of CD for tension, compression, bending, and shear can be found in Appendix Tables A-3.2, A-3.4, A-3.6, and A-3.8 respectively. It is sometimes necessary to check various combinations of loads (where the corresponding value of CD changes) to determine the critical loading condition. Since the strength of lumber depends on the duration of loading, it is possible that a smaller load, with a longer duration, will be more critical than a larger load that acts on the element for less time.
 
For example, consider a wooden column supporting the following loads:
  • a "construction" or roof live load, Lr = 6000 lb.
  • a live load, L = 20,000 lb.
  • a dead load, D = 15,000 lb.
  • a snow load, S = 16,000 lb.

Lr and S are not considered simultaneously since it is unlikely that roof maintenance or construction will occur during a major snow storm.
 
Several load combinations should be analyzed, per Chapter 2 Appendix Table A-2.7 (using Allowable Stress Design for wood):
 
1. D + L with CD = 1.0 (corresponding to the live load).
 
2. D + S with CD = 1.15 (corresponding to the snow load).
 
3. D + 0.75L + 0.75S with CD = 1.15 (corresponding to the snow load).
 
It is usually unnecessary to go through the entire design procedure for each load combination; instead, divide the loads in each case by the corresponding load duration factor to get a measure of the relative "load effects;" that is:
 
1. (15,000 + 20,000)/1.00 = 35,000/1.0 = 35,000 lb;
 
2. (15,000 + 8,000)/1.15 = 23,000/1.15 = 20,000 lb;
 
3. (15,000 + 0.75 × 20,000 + 0.75 × 16,000)/1.15 = 42,000/1.15 = 36,522 lb.
 
The third load combination is the critical one in this case, based on the underlined value being largest of the three choices. However, the structural element should be designed for the bold-faced value of 42,000 lb, and not the underlined value of 36,522 lb which is used only to determine the governing load value. The governing duration of load factor, CD = 1.15, will then be applied, not to the loads, but to the allowable stress.
 
Where only "occupancy" live loads and dead loads are present, CD can almost always be taken as 1.0 (corresponding to the load duration factor for live loads). The case of dead load acting alone, with CD = 0.9, is critical only when more than 90% of the total load is dead load.

 

Table A-3.11: Specific gravity for selected wood species ((based on oven-dry weight and volume)

Species or Species Combination
Specific Gravity
Species or Species Combination
Specific Gravity
Douglas Fir-Larch
0.50
Hem-Fir (North)
0.46
Douglas Fir-Larch (North)
0.49
Spruce-Pine-Fir
0.42
Douglas Fir-South
0.46
Spruce-Pine-Fir (South)
0.36
Hem-Fir
0.43
Southern Pine
0.55


Table A-3.12: Dimensions and properties of lumber1

 
wood cross section
 
Properties of rectangular cross sections:
Cross-sectional area, A = bd
Section modulus, Sx = bd2/6
Moment of inertia, Ix = bd3/12
Moment of inertia, Iy = db3/12
A. Dimension lumber
Dimension lumber nominal sizeActual size, b × d (in.)Area (in2)Sx (in3)Ix (in4)Iy (in4)
2 × 3
2 × 4
2 × 6
2 × 8
2 × 10
2 × 12
2 × 14
1.5 × 2.5
1.5 × 3.5
1.5 × 5.5
1.5 × 7.25
1.5 × 9.25
1.5 × 11.25
1.5 × 13.25
3.75
5.25
8.25
10.88
13.88
16.88
19.88
1.563
3.063
7.563
13.14
21.39
31.64
43.89
1.953
5.359
20.80
47.63
98.93
178.0
290.8
0.703
0.984
1.547
2.039
2.602
3.164
3.727
4 × 4
4 × 6
4 × 8
4 × 10
4 × 12
4 × 14
4 × 16
3.5 × 3.5
3.5 × 5.5
3.5 × 7.25
3.5 × 9.25
3.5 × 11.25
3.5 ×13.25
3.5 × 15.25
12.25
19.25
25.38
32.38
39.38
46.38
53.38
7.146
17.65
30.66
49.91
73.83
102.4
135.7
12.51
48.53
111.1
230.8
415.3
678.5
1034.4
12.51
19.65
25.90
33.05
40.20
47.34
54.49
B. Beams and stringers
Beams + Stringers nominal sizeActual size1, b × d (in.)Area (in2)Sx (in3)Ix (in4)Iy (in4)
6 × 10
6 × 12
6 × 14
6 × 16
6 × 18
6 × 20
6 × 22
5.5 × 9.5
5.5 × 11.5
5.5 × 13.5
5.5 × 15.5
5.5 × 17.5
5.5 × 19.5
5.5 × 21.5
52.25
63.25
74.25
85.25
96.25
107.3
118.3
82.73
121.2
187.1
220.2
280.7
348.6
423.7
393.0
697.1
1128
1707
2456
3398
4555
131.7
159.4
187.2
214.9
242.6
270.4
298.1
8 × 12
8 × 14
8 × 16
8 × 18
8 × 20
8 × 22
8 × 24
7.5 × 11.5
7.5 × 13.5
7.5 × 15.5
7.5 × 17.5
7.5 × 19.5
7.5 × 21.5
7.5 × 23.5
86.3
101.3
116.3
131.3
146.3
161.3
176.3
165.3
227.8
300.3
382.8
475.3
577.8
690.3
950.5
1538
2327
3350
4634
6211
8111
404.3
474.6
544.9
615.2
685.5
755.9
826.2
10 × 14
10 × 16
10 × 18
10 × 20
10 × 22
10 × 24
9.5 × 13.5
9.5 × 15.5
9.5 × 17.5
9.5 × 19.5
9.5 × 21.5
9.5 × 23.5
128.3
147.3
166.3
185.3
204.3
270.3
288.6
380.4
484.9
728.8
731.9
874.4
1948
2948
4243
5870
7868
10274
964.5
1107
1250
1393
1536
1679
12 × 16
12 × 18
12 × 20
12 × 22
12 × 24
11.5 × 15.5
11.5 × 17.5
11.5 × 19.5
11.5 × 21.5
11.5 × 23.5
178.3
201.3
224.3
247.3
270.3
460.5
587.0
728.8
886.0
1058
3569
5136
7106
9524
12437
1964
2218
2471
2725
2978
14 × 18
14 × 20
14 × 22
14 × 24
13.5 × 17.5
13.5 × 19.5
13.5 × 21.5
13.5 × 23.5
236.3
263.3
290.3
317.3
689.1
855.6
1040
1243
6029
8342
11181
14600
3588
3998
4408
4818
16 × 20
16 × 22
16 × 24
15.5 × 19.5
15.5 × 21.5
15.5 × 23.5
302.3
333.3
364.3
982.3
1194
1427
9578
12837
16763
6051
6872
7293
C. Posts and timbers
Posts + Timbers nominal sizeActual size1, b × d (in.)Area (in2)Sx (in3)Ix (in4)Iy (in4)
6 × 6
6 × 8
5.5 × 5.5
5.5 × 7.5
30.25
41.25
27.73
51.56
76.26
193.4
76.26
104.0
8 × 8
8 × 10
7.5 × 7.5
7.5 × 9.5
56.25
71.25
70.31
112.8
263.7
535.9
263.7
334.0
10 × 10
10 × 12
9.5 × 9.5
9.5 × 11.5
90.25
109.3
142.9
209.4
678.8
1204
678.8
821.7
12 × 12
12 × 14
11.5 × 11.5
11.5 × 13.5
132.3
155.3
253.5
349.3
1458
2358
1458
1711
14 × 14
14 × 16
13.5 × 13.5
13.5 × 15.5
182.3
209.3
410.1
540.6
2768
4189
2768
3178
16 × 16
16 × 18
15.5 × 15.5
15.5 × 17.5
240.3
271.3
620.6
791.1
4810
6923
4810
5431
18 × 18
18 × 20
17.5 × 17.5
17.5 × 19.5
306.3
341.3
893.2
1109
7816
10813
7816
8709

Note:

1. Actual sizes shown for "beams and stringers" and "posts and timbers" are minimum green dimensions — used for calculating the section properties listed in this table. For minimum dry sizes of these timbers, subtract 1/2 inch for 6-inch nominal dimensions, 3/4 inch for nominal dimensions greater than 6 and less than 16, and 1 inch for nominal dimensions 16 inches or greater.


Table A-3.13: Dimensions of typical glulam posts and beams1 (in.)

Southern Pine (1-3/8 in. laminations) Western Species2 (1-1/2 in. laminations)
Width (in.)
Depth (in.)
Width (in.)
Depth (in.)
2-1/8
5-1/2 to 24-3/4
2-1/8
6 to 27
3 or 3-1/8
5-1/2 to 24-3/4
3-1/8
6 to 27
5 or 5-1/8
5-1/2 to 35-3/4
5-1/8
6 to 36
6-3/4
6-7/8 to 48-1/8
6-3/4
7-1/2 to 48
8-1/2
8-1/4 to 63-1/4
8-3/4
9 to 63
10-1/2
9-5/8 to 77
10-3/4
10-1/2 to 81
12
11 to 86-5/8
12-1/4
12 to 88-1/2
14
13-3/4 to 100-3/8
14-1/4
13-1/2 to 102

Notes:

1. Values are for premium, architectural, and industrial appearance grades; framing appearance grades are generally surfaced less so that they match standard lumber widths, e.g., 2-1/2 in., 3-1/2 in., 5-1/2 in., and 7-1/4 in.

2. Western Species (WS) consists of numerous species groups, not all of which are produced in the western US, including: Alaska Cedar (AC); Douglas Fir-Larch (DF) and Douglas Fir South (DFS); Eastern Spruce (ES), Hem-Fir (HF); Softwood Species (SW); andSpruce Pine Fir (SPF).


Table A-3.14: Allowable force (lb) based on row and group tear-out1,2

Row tear-outGroup tear-out
Z'RT = rnn1(Fv')scrit(t) Z'GRT = n1(Fv')scrit(t) + Ft'At

Notes:

1. The terms in the equations for Z'RT and Z'GRT are defined as follows:

Z'RT = the maximum force that can be safely resisted by all fasteners subjected to row tear-out (lb)

Z'GRT = the maximum force that can be safely resisted by all fasteners subjected to group tear-out (lb)

rn = the number of rows of fasteners

n1 = the number of fasteners in a typical row

Fv' = the adjusted allowable shear stress for the wood element (psi)

Ft' = the adjusted allowable tension stress for the wood element (psi)

At = the area subjected to tension stress between the top and bottom rows of fasteners (in2)

scrit = the minimum spacing between fasteners, or the distance of the first fastener to the end of the member, if smaller (inches)

t = the member thickness (inches)

2. Row and group tear-out apply to wood tension members when the following conditions are met: (a) the direction of the tension force is parallel to the grain of the tension element; (b) the fasteners consist of bolts or lag screws; and (c) the connection consists of multiple fasteners in a row for row tear-out; and multiple rows of fasteners for group tear-out.


Table A-3.15: Maximum (actual) deflection in a beam1,2,3

Deflection coefficient, C, for maximum (actual) deflection, Δ (in.), where Δ =
equation
 equationequationequationequation
equation22.469.334.49216
equation35.9416.078.99n/a
equation61.3426.2713.31n/a
equation85.5436.1217.97n/a
equationn/an/an/a576

Notes:

1. Beam diagram symbols in top row of tables represent the following conditions (from left to right): simply-supported; one end pinned and one end continuous; both ends continuous; and cantilever.

2. Units for the maximum (actual) deflection equation are as follows:

  Δ = maximum (actual) deflection (in.)

  C = deflection coefficient

  L = span (in.): The quantity (L/12) that appears in the deflection equation is therefore the span in feet

  E = modulus of elasticity (psi when load is in lb; or ksi when load is in kips)

  Ix = moment of inertia about axis of bending (in4)

  P = concentrated load or resultant of uniformly-distributed load (lb or kips)

  w = uniformly-distributed load (lb/ft or kips/ft)

3. Allowable deflections (from Appendix Table A-1.3) are as follows:

  For live load only (or snow or wind only), the typical basic floor beam limit is L/360 while typical roof beam limits are L/180, L/240, or L/360 (for no ceiling, nonplaster ceiling, or plaster ceiling respectively).

  For total loads (combined live and dead), the typical basic floor beam limit is L/240 while typical roof beam limits are L/120, L/180, or L/240 (for no ceiling, nonplaster ceiling, or plaster ceiling respectively).


Table A-3.16: "Adjusted" section modulus (CFSx) values for wood sections in bending (lightest shown in bold face)1,2

Shape
CFSx (in3)
Shape
CFSx (in3)
Shape
CFSx (in3)
2 × 4
4 4.594
6 × 10
82.73
8 × 22
541.6
Double 2 × 4
9.188
Triple 2 × 12
94.92
12 × 18
562.9
2 × 6
9.831
4 × 14
102.4
10 × 20
570.4
Triple 2 × 4
13.78
Triple 2 × 14
118.5
8 × 24
640.6
2 × 8
15.77
6 × 12
121.2
14 × 18
660.8
Double 2 × 6
19.66
4 × 16
135.7
10 × 22
686.0
4 × 6
22.94
6 × 14
164.9
12 × 20
690.5
2 × 10
25.53
8 × 12
165.3
14 × 20
810.6
Triple 2 × 6
29.49
6 × 16
214.1
10 × 24
811.5
Double 2 × 8
31.54
8 × 14
224.9
12 × 22
830.4
2 × 12
31.64
6 × 18
269.2
16 × 20
930.7
2 × 14
39.50
10 × 14
284.8
14 × 22
974.8
4 × 8
39.86
8 × 16
291.9
12 × 24
982.3
Double 2 × 10
47.06
6 × 20
330.3
16 × 22
1119
Triple 2 8
47.31
8 18
367.1
14 24
1153
4 10
59.89
10 16
369.7
18 22
1264
Double 2 12
63.28
6 22
397.1
16 24
1324
Triple 2 10
70.59
12 16
447.6
20 22
1408
Double 2 14
79.00
8 20
450.4
18 24
1495
4 12
81.21
10 18
465.0
20 24
1666

Notes:

1. "Double" or "triple" indicates that two or three sections, respectively, are nailed together to create a single bending element.

2. The "adjusted" section modulus consists of the size factor, CF, multiplied by the section modulus, Sx.


Table A-3.17: Selected lag screw (lag bolt) dimensions

 
dimensions of lag screw
L (in.)D (in.)Dr (in.)T (in.)TE (in.)E (in.)
30.2500.1732.00.15620.1562
30.3750.2652.00.21870.2187
30.5000.3712.00.31250.3125
30.6250.4712.00.40620.4062
40.2500.1732.50.15620.1562
40.3750.2652.50.21870.2187
40.5000.3712.50.31250.3125
40.6250.4712.50.40620.4062
50.2500.1733.00.15620.1562
50.3750.2653.00.21870.2187
50.5000.3713.00.31250.3125
50.6250.4713.00.40620.4062
60.2500.1733.50.15620.1562
60.3750.2653.50.21870.2187
60.5000.3713.50.31250.3125
60.6250.4713.50.40620.4062


Table A-3.18: Selected common wire nail dimensions

 
dimensions of common nail
Designation1L (in.)D (in.)2E (in.)
6d2.000.1130.226
8d 2.500.1310.262
10d3.000.1480.296
12d3.250.1480.296
16d3.500.1620.324
20d4.000.1920.384
30d4.500.2070.414
40d5.000.2250.450
50d5.500.2440.488

Notes:

1. The designation for nails once had some relation to the cost of 100 nails; it now refers only to the nail's size. The letter "d" in the designation refers to the pennyweight of the nails and is said to be derived from the biblical use of denarius (hence "d") as the historical equivalent of the modern penny (hence "pennyweight"). We continue to use the abbreviation "d" to stand for "penny" and we say "10-penny nail" when reading "10d nail."

2. E = approximate length of tapered tip, assumed to be equal to 2D.


Table A-3.19: Penetration and dowel bearing length1

Type of fastenerRequired penetration distance, p
Absolute minimumMinimum for full value of Z
Lag screw2
shear on lag screw
4D8D
Nail3
shear on lag screw
6D10D
Bolt4
 
n/an/a

Notes:

1. The dowel bearing length in the main member (lm), used in yield limit calculations, may be different from the penetration as defined in the illustrations above: for lag screws, the dowel bearing length in the main member equals the penetration (which excludes the tapered tip); however, for nailed connections, the dowel bearing length in the main member equals the penetration (which includes the tapered tip) minus half the length of the tapered tip.

2. For lag screws where the penetration, p, falls between the two values shown in the table, the lateral design value, Z, is multiplied by p/(8D). Therefore, where the penetration equals the absolute minimum value of 4D, the lateral design value is taken as one half the tabular (or computed) value of Z.

3. For nails where the penetration, p, falls between the two values shown in the table, the lateral design value, Z, is multiplied by p/(10D). Therefore, where the penetration equals the absolute minimum value of 6D, the lateral design value is taken as 0.6 times the tabular (or computed) value of Z.

4. For bolts, "penetration" is always, by definition, 100% through both the main member and side member(s), so there is no need to calculate its effect on the lateral design value, Z.


Table A-3.20: Duration of load adjustment factor, CD, for wood connectors1

C. Load duration factor
Load duration factor, CD, is as follows:
Load type
Duration
CD
Load type
Duration
CD
Dead load, D
Permanent
0.90
Construction load, Lr
1 week
1.25
Live load, L
10 years
1.00
Wind load, W
10 minutes
1.60
Snow load, S
2 months
1.15
Seismic load, E
10 minutes
1.60

Note:

1. Applies to both dowel-type connectors and connectors subject to withdrawal loads

 
 

Table A-3.21: Wet service adjustment factor, CM, for wood connectors1,2

Fastener type with lateral loadCM
"Dowel-type," wet when made, dry in-service:
  • 1 fastener only
  • 2 or more fasteners in single row parallel to grain
  • Multiple rows of fasteners parallel to grain, separate splice plate each row
  • Fastener with diameter < 1/4 in.
  • Multiple rows of fasteners with diameter ≥ 1/4 in., without separate splice plates
"Dowel-type," wet when used (in-service)
varies as follows:
1.00
1.00
1.00
0.70
0.40
0.70
Fastener type with withdrawal loadCM
Nails, wet when made, dry in-service
Nails, dry when made, wet in-service
Nails, wet when made, wet in-service
Lag screws and wood screws, wet in-service
0.25
0.25
1.00
0.70

Notes:

1. Applies to both dowel-type connectors and connectors subject to withdrawal loads.

2. CM = 1.0 for fasteners that are dry when fabricated and when used (in-service).


Table A-3.22: Group action adjustment factor, Cg, for wood connectors1,2,3,4

A. Cg, bolt (or lag screw) connections, wood members with same properties: E = 1,400,000 psi; bolt or lag screw diameter, D = 3/4 in.; spacing between fasteners in a row, s = 3 in.
Am = Area of main member, in2 number fasteners in row As = Area of side member(s), in2
5 8 11 14 17 30 40 56 64
  5 2
3
4
5
6
7
8
9
10
1.000
0.984
0.954
0.914
0.867
0.817
0.766
0.716
0.669
0.991
0.962
0.918
0.866
0.809
0.752
0.698
0.647
0.601
0.987
0.952
0.902
0.844
0.783
0.723
0.667
0.616
0.570
0.985
0.947
0.893
0.831
0.768
0.707
0.650
0.598
0.552
0.983
0.943
0.887
0.823
0.758
0.696
0.638
0.587
0.540
0.980
0.936
0.875
0.807
0.739
0.675
0.616
0.563
0.517
0.979
0.933
0.871
0.802
0.733
0.688
0.608
0.556
0.510
0.978
0.931
0.868
0.798
0.728
0.662
0.602
0.549
0.503
0.978
0.931
0.867
0.796
0.726
0.660
0.600
0.547
0.501
  8 2
3
4
5
6
7
8
9
10
0.991
0.962
0.918
0.866
0.809
0.752
0.698
0.647
0.601
1.000
0.990
0.971
0.943
0.910
0.873
0.833
0.792
0.751
0.996
0.979
0.953
0.918
0.877
0.834
0.790
0.746
0.704
0.993
0.973
0.942
0.903
0.859
0.812
0.766
0.720
0.677
0.992
0.970
0.936
0.894
0.847
0.798
0.750
0.703
0.659
0.989
0.962
0.922
0.875
0.823
0.770
0.719
0.670
0.624
0.988
0.959
0.918
0.869
0.815
0.761
0.708
0.659
0.613
0.987
0.957
0.914
0.863
0.809
0.753
0.700
0.650
0.603
0.987
0.956
0.913
0.862
0.806
0.751
0.697
0.647
0.600
  11 2
3
4
5
6
7
8
9
10
0.987
0.952
0.902
0.844
0.783
0.723
0.667
0.616
0.570
0.996
0.979
0.953
0.918
0.877
0.834
0.790
0.746
0.704
1.000
0.993
0.978
0.958
0.932
0.903
0.870
0.836
0.801
0.998
0.986
0.967
0.942
0.911
0.877
0.841
0.804
0.766
0.996
0.983
0.961
0.932
0.898
0.861
0.822
0.783
0.744
0.993
0.975
0.947
0.911
0.871
0.828
0.785
0.741
0.700
0.992
0.972
0.942
0.905
0.862
0.818
0.772
0.728
0.685
0.991
0.970
0.938
0.899
0.855
0.809
0.762
0.717
0.673
0.991
0.969
0.937
0.897
0.853
0.806
0.759
0.713
0.669
Am = Area of main member, in2 number fasteners in row As = Area of side member(s), in2
5 8 11 14 17 30 40 56 64
  14 2
3
4
5
6
7
8
9
10
0.985
0.947
0.893
0.831
0.768
0.707
0.650
0.598
0.552
0.993
0.973
0.942
0.903
0.859
0.812
0.766
0.720
0.677
0.998
0.986
0.967
0.942
0.911
0.877
0.841
0.804
0.766
1.000
0.994
0.983
0.966
0.945
0.921
0.894
0.864
0.834
0.998
0.990
0.976
0.956
0.931
0.903
0.873
0.841
0.808
0.995
0.982
0.961
0.934
0.902
0.867
0.831
0.793
0.756
0.994
0.979
0.956
0.927
0.893
0.856
0.817
0.778
0.739
0.993
0.977
0.952
0.921
0.885
0.846
0.805
0.765
0.725
0.993
0.976
0.951
0.919
0.883
0.843
0.802
0.761
0.721
  17 2
3
4
5
6
7
8
9
10
0.983
0.943
0.887
0.823
0.758
0.696
0.638
0.587
0.540
0.992
0.970
0.936
0.894
0.847
0.798
0.750
0.703
0.659
0.996
0.983
0.961
0.932
0.898
0.861
0.822
0.783
0.744
0.998
0.990
0.976
0.956
0.931
0.903
0.873
0.841
0.808
1.000
0.995
0.986
0.972
0.954
0.934
0.910
0.885
0.858
0.997
0.987
0.971
0.950
0.924
0.895
0.864
0.832
0.799
0.996
0.984
0.966
0.943
0.914
0.883
0.850
0.815
0.781
0.995
0.982
0.962
0.936
0.906
0.873
0.837
0.801
0.765
0.995
0.981
0.961
0.934
0.904
0.869
0.833
0.797
0.760
  30 2
3
4
5
6
7
8
9
10
0.980
0.936
0.875
0.807
0.739
0.675
0.616
0.563
0.517
0.989
0.962
0.922
0.875
0.823
0.770
0.719
0.670
0.624
0.993
0.975
0.947
0.911
0.871
0.828
0.785
0.741
0.700
0.995
0.982
0.961
0.934
0.902
0.867
0.831
0.793
0.756
0.997
0.987
0.971
0.950
0.924
0.895
0.864
0.832
0.799
1.000
0.997
0.992
0.984
0.973
0.961
0.946
0.930
0.912
0.999
0.995
0.987
0.976
0.963
0.947
0.929
0.909
0.888
0.998
0.992
0.983
0.969
0.953
0.935
0.914
0.891
0.867
0.998
0.991
0.981
0.967
0.950
0.931
0.909
0.886
0.861
Am = Area of main member, in2 number fasteners in row As = Area of side member(s), in2
5 8 11 14 17 30 40 56 64
  40 2
3
4
5
6
7
8
9
10
0.979
0.933
0.871
0.802
0.733
0.668
0.608
0.556
0.510
0.988
0.959
0.918
0.869
0.815
0.761
0.708
0.659
0.613
0.992
0.972
0.942
0.905
0.862
0.818
0.772
0.728
0.685
0.994
0.979
0.956
0.927
0.893
0.856
0.817
0.778
0.739
0.996
0.984
0.966
0.943
0.914
0.883
0.850
0.815
0.781
0.999
0.995
0.987
0.976
0.963
0.947
0.929
0.909
0.888
1.000
0.998
0.994
0.988
0.980
0.970
0.959
0.946
0.932
0.999
0.996
0.989
0.981
0.970
0.957
0.943
0.927
0.909
0.999
0.995
0.988
0.979
0.967
0.954
0.938
0.921
0.902
  56 2
3
4
5
6
7
8
9
10
0.978
0.931
0.868
0.798
0.728
0.662
0.602
0.549
0.503
0.987
0.957
0.914
0.863
0.809
0.753
0.700
0.650
0.603
0.991
0.970
0.938
0.899
0.855
0.809
0.762
0.717
0.673
0.993
0.977
0.952
0.921
0.885
0.846
0.805
0.765
0.725
0.995
0.982
0.962
0.936
0.906
0.873
0.837
0.801
0.765
0.998
0.992
0.983
0.969
0.953
0.935
0.914
0.891
0.867
0.999
0.996
0.989
0.981
0.970
0.957
0.943
0.927
0.909
1.000
0.999
0.996
0.991
0.985
0.978
0.970
0.961
0.950
1.000
0.998
0.994
0.989
0.982
0.974
0.965
0.954
0.942
  64 2
3
4
5
6
7
8
9
10
0.978
0.931
0.867
0.796
0.726
0.660
0.600
0.547
0.501
0.987
0.956
0.913
0.862
0.806
0.751
0.697
0.647
0.600
0.991
0.969
0.937
0.897
0.853
0.806
0.759
0.713
0.669
0.993
0.976
0.951
0.919
0.883
0.843
0.802
0.761
0.721
0.995
0.981
0.961
0.934
0.904
0.869
0.833
0.797
0.760
0.998
0.991
0.981
0.967
0.950
0.931
0.909
0.886
0.861
0.999
0.995
0.988
0.979
0.967
0.954
0.938
0.921
0.902
1.000
0.998
0.994
0.989
0.982
0.974
0.965
0.954
0.942
1.000
0.999
0.996
0.992
0.987
0.981
0.974
0.965
0.956
  
B. Cg, bolt (or lag screw) connections, wood main member with E = 1,400,000 psi; steel side member(s) with E= 29,000,000 psi; bolt or lag screw diameter, D = 3/4 in.; spacing between fasteners in a row, s = 3 in.
Am = Area of main member, in2 number fasteners in row As = Area of steel side member(s), in2
1 2 3 4 5 7 10 12 15
  5 2
3
4
5
6
7
8
9
10
0.973
0.915
0.838
0.758
0.682
0.613
0.554
0.502
0.458
0.969
0.905
0.824
0.739
0.660
0.591
0.531
0.480
0.436
0.968
0.902
0.819
0.733
0.653
0.583
0.523
0.472
0.429
0.967
0.900
0.816
0.730
0.650
0.579
0.519
0.468
0.425
0.967
0.899
0.815
0.728
0.648
0.577
0.517
0.466
0.423
0.966
0.898
0.813
0.726
0.645
0.575
0.514
0.463
0.420
0.966
0.897
0.812
0.724
0.643
0.573
0.512
0.461
0.419
0.966
0.897
0.811
0.724
0.643
0.572
0.512
0.461
0.418
0.966
0.896
0.811
0.723
0.642
0.571
0.511
0.460
0.417
  8 2
3
4
5
6
7
8
9
10
0.986
0.951
0.901
0.843
0.782
0.722
0.666
0.615
0.569
0.982
0.941
0.884
0.819
0.754
0.691
0.633
0.580
0.534
0.980
0.937
0.878
0.812
0.744
0.680
0.621
0.569
0.522
0.980
0.935
0.875
0.808
0.740
0.675
0.616
0.563
0.517
0.979
0.934
0.874
0.806
0.737
0.672
0.612
0.560
0.513
0.979
0.933
0.872
0.803
0.734
0.668
0.609
0.556
0.509
0.978
0.932
0.870
0.801
0.731
0.666
0.606
0.553
0.506
0.978
0.932
0.870
0.800
0.730
0.664
0.605
0.552
0.505
0.978
0.932
0.869
0.799
0.729
0.663
0.604
0.550
0.504
  11 2
3
4
5
6
7
8
9
10
0.992
0.970
0.935
0.892
0.844
0.794
0.745
0.698
0.654
0.988
0.959
0.916
0.866
0.811
0.756
0.703
0.653
0.608
0.986
0.955
0.910
0.857
0.800
0.743
0.689
0.639
0.592
0.986
0.953
0.907
0.853
0.795
0.737
0.682
0.631
0.585
0.985
0.952
0.905
0.850
0.792
0.733
0.678
0.627
0.580
0.985
0.951
0.903
0.847
0.788
0.729
0.673
0.622
0.575
0.984
0.950
0.902
0.845
0.785
0.726
0.670
0.618
0.571
0.984
0.950
0.901
0.844
0.784
0.725
0.668
0.616
0.569
0.984
0.949
0.900
0.843
0.783
0.723
0.667
0.615
0.568
Am = Area of main member, in2 number fasteners in row As = Area of steel side member(s), in2
1 2 3 4 5 7 10 12 15
  14 2
3
4
5
6
7
8
9
10
0.996
0.981
0.956
0.924
0.886
0.846
0.804
0.762
0.721
0.991
0.969
0.936
0.896
0.850
0.802
0.755
0.709
0.665
0.990
0.966
0.930
0.886
0.838
0.788
0.739
0.691
0.647
0.989
0.964
0.927
0.882
0.832
0.781
0.731
0.683
0.638
0.989
0.963
0.925
0.879
0.829
0.777
0.726
0.677
0.632
0.988
0.961
0.923
0.876
0.825
0.772
0.721
0.671
0.626
0.988
0.960
0.921
0.873
0.822
0.768
0.716
0.667
0.621
0.988
0.960
0.920
0.873
0.820
0.767
0.715
0.665
0.619
0.988
0.960
0.920
0.872
0.819
0.766
0.713
0.664
0.617
  17 2
3
4
5
6
7
8
9
10
0.998
0.988
0.970
0.946
0.917
0.884
0.849
0.813
0.777
0.994
0.976
0.950
0.917
0.878
0.837
0.795
0.753
0.712
0.992
0.973
0.943
0.907
0.865
0.822
0.777
0.733
0.691
0.991
0.971
0.940
0.902
0.859
0.814
0.768
0.723
0.680
0.991
0.970
0.938
0.899
0.855
0.809
0.763
0.717
0.674
0.990
0.968
0.936
0.896
0.851
0.804
0.757
0.711
0.667
0.990
0.967
0.934
0.893
0.848
0.800
0.752
0.706
0.661
0.990
0.967
0.934
0.892
0.847
0.799
0.750
0.704
0.659
0.990
0.967
0.933
0.892
0.845
0.797
0.749
0.702
0.657
  30 2
3
4
5
6
7
8
9
10
0.997
0.987
0.970
0.947
0.919
0.888
0.855
0.821
0.786
0.998
0.991
0.980
0.964
9.944
0.921
0.896
0.869
0.841
0.997
0.988
0.973
0.953
0.929
0.902
0.873
0.843
0.812
0.996
0.986
0.969
0.948
0.922
0.893
0.862
0.830
0.797
0.996
0.984
0.967
0.945
0.918
0.888
0.856
0.822
0.788
0.995
0.983
0.965
0.941
0.913
0.881
0.848
0.813
0.779
0.995
0.982
0.963
0.938
0.909
0.877
0.842
0.807
0.771
0.995
0.982
0.962
0.937
0.908
0.875
0.840
0.804
0.768
0.994
0.981
0.962
0.936
0.906
0.873
0.838
0.802
0.765
Am = Area of main member, in2 number fasteners in row As = Area of steel side member(s), in2
1 2 3 4 5 7 10 12 15
  40 2
3
4
5
6
7
8
9
10
0.996
0.983
0.963
0.936
0.905
0.871
0.835
0.798
0.761
1.000
0.996
0.990
0.981
0.968
0.954
0.937
0.919
0.899
0.998
0.993
0.983
0.970
0.953
0.934
0.913
0.890
0.865
0.998
0.991
0.979
0.964
0.945
0.924
0.900
0.875
0.849
0.997
0.989
0.977
0.961
0.941
0.918
0.893
0.867
0.839
0.997
0.988
0.975
0.957
0.936
0.911
0.885
0.857
0.828
0.996
0.987
0.973
0.954
0.932
0.906
0.879
0.849
0.819
0.996
0.987
0.972
0.953
0.930
0.904
0.876
0.847
0.816
0.996
0.986
0.971
0.952
0.929
0.902
0.874
0.844
0.813
  56 2
3
4
5
6
7
8
9
10
0.994
0.980
0.957
0.927
0.893
0.856
0.817
0.778
0.740
0.999
0.994
0.985
0.974
0.959
0.942
0.922
0.901
0.879
1.000
0.997
0.992
0.984
0.975
0.963
0.950
0.935
0.919
0.999
0.995
0.988
0.979
0.967
0.953
0.937
0.919
0.901
0.998
0.994
0.986
0.975
0.962
0.947
0.929
0.910
0.890
0.998
0.992
0.983
0.971
0.957
0.939
0.920
0.899
0.877
0.998
0.991
0.982
0.969
0.953
0.934
0.914
0.891
0.868
0.997
0.991
0.981
0.967
0.951
0.932
0.911
0.888
0.864
0.997
0.991
0.980
0.966
0.949
0.930
0.908
0.885
0.860
  64 2
3
4
5
6
7
8
9
10
0.994
0.979
0.955
0.925
0.890
0.852
0.812
0.772
0.733
0.998
0.993
0.983
0.971
0.955
0.936
0.916
0.893
0.869
1.000
0.998
0.994
0.987
0.980
0.970
0.959
0.946
0.932
0.999
0.996
0.991
0.983
0.974
0.962
0.949
0.935
0.919
0.999
0.995
0.989
0.980
0.969
0.956
0.941
0.925
0.907
0.998
0.994
0.986
0.976
0.963
0.949
0.932
0.914
0.894
0.998
0.993
0.984
0.973
0.959
0.943
0.925
0.905
0.884
0.998
0.992
0.984
0.972
0.958
0.941
0.922
0.902
0.881
0.998
0.992
0.983
0.971
0.956
0.939
0.920
0.899
0.877

Notes:

1. Values are conservative when using smaller fastener diameter, smaller fastener spacing, and greater modulus of elasticity.

2. For both the table and the exact method shown below, cross-sectional areas are used for Am and As when the member is loaded parallel to grain; when loaded perpendicular to grain, an equivalent area is used for Am or As, based on the member thickness (measured in a direction parallel to the fastener) multiplied by an equivalent member width. This equivalent width is taken as the distance between the outer rows of fasteners or, where there is only one row of fasteners, as the minimum spacing between rows that would be computed if there were multiple rows of fasteners.

3. Cg = 1.0 for dowel-type fasteners with diameter, D < 0.25 in. Other values for Cg can be determined exactly (for fastener diameters greater than 0.25 in. and less than or equal to 1.0 in.) based on the following method:

  a. Find the bolt or lag screw diameter, D; then find the so-called load/slip modulus, γ, as follows:

 γ  γ = 180,000(D1.5) for dowel-type fasteners in wood-wood connection; γ = 270,000(D1.5) for dowel-type fasteners in wood-metal connection

  b. Find s, the spacing (center-to-center) between fasteners in a row;

  c. Find Em and Es, the moduli of elasticity (psi) for the main and secondary members, respectively;

  d. Find Am and As, the cross-sectional areas (in2) for the main member and for the side member (or the sum of the areas of the side members, if there are more than one), respectively;

  equations

4. Applies to dowel-type connectors only.


Table A-3.23: Geometry adjustment factor, CΔ, for wood connectors (bolts and lag screws)

A. Spacing (in.) between fasteners in a rowa,b,d
Loading direction Absolute minimum Minimum for full value
Parallel to grain3D4D
Perpendicular to grain3DWhatever is required for attached membersc

Notes for Part A:

a. Required spacing (in.) is a multiple of the fastener diameter, D (in.).

b. A distance below the absolute minimum is, of course, not permitted — in that case, the geometry factor, CΔ = 0. For any distance equal to or greater than the "minimum for full value," the geometry factor, CΔ = 1.0. For spacing between the two values shown in the table, the geometry factor, CΔ, is taken as the actual spacing divided by the minimum spacing for full value. For example, if the actual spacing between fasteners in a row, where the load was parallel to grain, is 3.5D, the geometry factor, CΔ = 3.5D/(4D) = 0.875. If the spacing in this case equaled the absolute minimum of 3D, the geometry factor, CΔ = 3D/(4D) = 0.75.

c. For fasteners in a row, where the loading is perpendicular to grain, the minimum spacing necessary to obtain the full value of the geometry factor, i.e., CΔ = 1.0, is based on meeting the requirements for the member to which it is attached — i.e., the member whose load is parallel to grain — as long as this distance is no less than the absolute minimum value of 3D (assuming that both members in the connection are not oriented so that the load is perpendicular to grain).

d. See general notes below.

B. Spacing (in.) between rows of fastenersa,b,d
Loading direction Condition Minimum spacing
Parallel to grainAll conditions1.5D
Perpendicular to grainc l/D ≤ 2
2 < l/D < 6
l/D ≥ 6
2.5D
(5l + 10D)/8
5D

Notes for Part B:

a. Required spacing (in.) is a multiple of the fastener diameter, D (in.).

b. Where the minimum spacing between rows of fasteners is met, the geometry factor, CΔ = 1.0. Otherwise, where the spacing is below the minimum allowed, the connection is not permitted — i.e., CΔ = 0. Interestingly, the maximum spacing between rows of fasteners is also limited in the following way: a 5 in. maximum limit is placed on the spacing between the outer rows of fasteners, in cases where the rows are parallel to the grain of the wood. This reduces the possibility of splitting as the wood member shrinks or expands (due to changes in its moisture content) perpendicular to the grain, while the bolts are fixed in place by a connecting member.

c. The fastener length, l (in.), is defined as the length of the fastener that is actually embedded within either the main member (the dowel bearing length — see Appendix Table A-3.27), or the total length within one or more secondary members, whichever is smaller. D is the fastener diameter (in.).

d. See general notes below.

C. End distance (in.)a,b,c
Loading direction Absolute minimum Minimum for full value
Parallel to grain:
 
 
Compression
Tension — softwood
Tension — hardwood
2D
3.5D
2.5D
4D
7D
5D
Perpendicular to grain 2D 4D

Notes for Part C:

a. Required end distance (in.) is a multiple of the fastener diameter, D (in.).

b. A distance below the absolute minimum is, of course, not permitted — in that case, the geometry factor, CΔ = 0; for any distance equal to or greater than the "minimum for full value," the geometry factor, CΔ = 1.0. For end distances between the two values shown in the table, the geometry factor, CΔ, is taken as the actual end distance divided by the minimum distance for full value. For example, if the end distance of a fastener loaded parallel to grain in compression is 3D, the geometry factor, CΔ = 3D/(4D) = 0.75. If the end distance in this case equaled the absolute minimum of 2D, the geometry factor, CΔ = 2D/(4D) = 0.50.

c. See general notes below.

D. Edge distance (in.)a,b,d,e
Loading direction Condition1 Minimum Edge Distance
Parallel to grain
l/D ≤ 6
l/D > 6
1.5D
the greater of 1.5D or 1.2 spacing between rows
Perpendicular to grainc loaded edge
unloaded edge
4D
1.5D

Notes for Part D:

a. Required edge distance (in.) is a multiple of the fastener diameter, D (in.).

b. Where the loading direction is parallel to grain, let l be the fastener length that is actually embedded within either the main member (the dowel bearing length — see Appendix Table A-3.19), or the total length within one or more secondary members, whichever is smaller. D is the bolt or lag screw diameter.

c. Loads should not be suspended in such a way that fasteners are stressing the wood members perpendicular to grain where such fasteners are inserted below the neutral axis (that is, in the tension region) of a single beam.

d. Where the minimum edge distance is met, the geometry factor, CΔ = 1.0. Otherwise, the connection is not permitted — i.e., CΔ = 0.

e. See general notes below.

E. Spacing and end-edge distances for loading parallel and perpendicular to grain
spacing and end-edge distance diagrams End distance is measured parallel to grain at the end of the member. Where the load is also parallel to grain, a distinction is made between the two member ends — one of which is in tension (that is, where the fastener is bearing towards the member end) and one of which is in compression (where the fastener is bearing away from the member end)
Edge distance is measured perpendicular to grain, for load parallel to grain
Loaded edge distance is measured perpendicular to grain, for load perpendicular to grain; it refers to the edge that is "pushing" on the fasteners, i.e., the edge where the fasteners are pushing against the member edge
Unloaded edge distance is measured perpendicular to grain, for load perpendicular to grain; it refers to the opposite edge that isn't loaded, that is, the edge where the fasteners are not pushing against the member edge
Both spacing between fasteners in a row, and spacing between rows of fasteners, are self-evident, requiring only that a "row of fasteners" is clearly understood as being parallel to the direction of load, and having no necessary relationship to the direction of grain in the wood members

General notes for Table A-3.23:

1. The geometry factor for any connection is taken as the smallest single value computed for any fastener in the connection, based on any of the criteria listed in Appendix Table A-3.23 parts A, B, C, or D, i.e., for both spacing requirements as well as for end and edge distance. All such required spacing and distances are computed as multiples of the fastener diameter, D, for all wood fasteners comprising the connection; but only the smallest geometry factor found within the entire connection is applied to the connection design.

2. CΔ = 1.0 for "end distance" and "spacing between fasteners in a row" when minimum conditions for the full value are met. There are also smaller allowable lengths for these parameters (although subject to an absolute minimum) which, while permitted, reduce the geometry factor to a value less than 1.0.

3. A fastener row refers to a minimum of two fasteners in a line parallel to the direction of the load, whether or not it is parallel or perpendicular to the direction of the grain of wood. On the other hand, end and edge distance are measured parallel and perpendicular, respectively, to the direction of grain, not load, as shown in Appendix Table A-3.23, part E.

4. Applies to dowel-type connectors only, and only when the fastener diameter, D ≥ 1/4 in. Otherwise, CΔ = 1.0.


Table A-3.24: Toe-nail adjustment factor, Ctn, for nails1

toe nail diagram DiagramDirection of Applied Force Ctn
toe nail diagram For lateral design values, Z, bearing lengths are as follows:
  • ln main member: lm = ln cos 30° – ln / 3
  • In side member: ls = ln / 3
where ln = length of nail
0.83
toe nail diagram For withdrawal design values, W, depth of penetration, pw is actual length of nail in main member. 0.67

Note:

1. Toe-nailing values are based on two assumptions:

  a. That the nail is driven at an angle of approximately 30° to the face of the side member.

  b. That the nail insertion point is 1/3 of the nail length (ln / 3) above the end of the side member.

 
 

Table A-3.25: Temperature factor, Ct, for wood fasteners

Temperature, T, (°F)Ct (used dry)Ct (used wet)
T ≤ 100°F1.01.0
100°F < T ≤ 125°F0.80.7
125°F < T ≤ 150°F0.70.5


Table A-3.26: Lateral design value, Z (lb) for bolts: single-shear connections, with 1-1/2 in. side member thickness, both members same species (or same specific gravity)1

A. Designation for single-shear lateral design values according to direction of grain2
 
lateral design value diagrams
B. 1-1/2 in. main member thickness
Species or Species Combination 1/2 in. diameter Bolts3/4 in. diameter Bolts1 in. diameter Bolts
ZparZs-perZm-per ZparZs-perZm-per ZparZs-perZm-per
Douglas Fir-Larch480300300720420420970530530
Douglas Fir-Larch (North)470290290710400400950510510
Douglas Fir-South440270270670380380890480480
Hem-Fir410250250620350350830440440
Hem-Fir (North)440270270670380380890480480
Spruce-Pine-Fir410240240610340340810430430
Spruce-Pine-Fir (South)350200200520280280700360360
Southern Pine5303303308004604601060580580
C. 3-1/2 in. main member thickness
Species or Species Combination 1/2 in. diameter Bolts3/4 in. diameter Bolts1 in. diameter Bolts
ZparZs-perZm-per ZparZs-perZm-per ZparZs-perZm-per
Douglas Fir-Larch61037043012005906101830680740
Douglas Fir-Larch (North)61036042011905604901790650710
Douglas Fir-South58034040011405205501680600660
Hem-Fir55032038011004605001570540600
Hem-Fir (North)58034040011405205501680600660
Spruce-Pine-Fir54032037010804504801530530590
Spruce-Pine-Fir (South)4902803009903604001320420480
Southern Pine66040047012706606902010770830
D. 5-1/2 in. main member thickness
Species or Species Combination 5/8 in. diameter Bolts3/4 in. diameter Bolts1 in. diameter Bolts
ZparZs-perZm-per ZparZs-perZm-per ZparZs-perZm-per
Douglas Fir-Larch610370430120059079020506801060
Douglas Fir-Larch (North)610360420119056078020306501010
Douglas Fir-South58034040011405207401930600940
Hem-Fir55032038011004607001800540860
Hem-Fir (North)58034040011405207401930600940
Spruce-Pine-Fir54032037010804506901760530830
Spruce-Pine-Fir (South)4902803309903605701520420680
Southern Pine660400470127066085021507701190

Notes:

1. Member thickness is measured parallel to the axis of the fastener.

2. Designations for lateral design values are as illustrated: (a) Zpar for both members with direction of grain parallel to load; (b) Zs-per for side member with grain perpendicular to load and main member with grain parallel to load; and (c) Zm-per for main member with grain perpendicular to load and side member with grain parallel to load. A fourth possibility, with both members having grain perpendicular to the direction of load, is rarely encountered and not included here. The official designations also shown below the illustrations contain "parallel" and "perpendicular" symbols instead of the abbreviations, "par" and "per" used in these tables and text.


Table A-3.27: Lateral design value, Z (lb) for bolts: double-shear connections, with 1-1/2 in. side member thickness, both members same species (or same specific gravity)1

A. Designation for double-shear lateral design values according to direction of grain2
 
lateral design value diagrams
B. 1-1/2 in. main member thickness
Species or Species Combination 1/2 in. diameter Bolts3/4 in. diameter Bolts1 in. diameter Bolts
ZparZs-perZm-per ZparZs-perZm-per ZparZs-perZm-per
Douglas Fir-Larch10507304701580117059021001350680
Douglas Fir-Larch (North)10307204601550113056020601290650
Douglas Fir-South9706804201450104052019301200600
Hem-Fir900650380135092046018001080540
Hem-Fir (North)9706804201450104052019301200600
Spruce-Pine-Fir880640370132090045017601050530
Spruce-Pine-Fir (South)76056029011407203601520840420
Southern Pine11508005501730133066023101530770
C. 3-1/2 in. main member thickness
Species or Species Combination 1/2 in. diameter Bolts3/4 in. diameter Bolts1 in. diameter Bolts
ZparZs-perZm-per ZparZs-perZm-per ZparZs-perZm-per
Douglas Fir-Larch1230730860240011701370409013501580
Douglas Fir-Larch (North)1210720850238011301310405012901510
Douglas Fir-South1160680810228010401210386012001400
Hem-Fir110065076021909201080360010801260
Hem-Fir (North)1160680810228010401210386012001400
Spruce-Pine-Fir108064074021609001050353010501230
Spruce-Pine-Fir (South)98056066019907208403040840980
Southern Pine1320800940255013301550431015301790
D. 5-1/2 in. main member thickness
Species or Species Combination 5/8 in. diameter Bolts3/4 in. diameter Bolts1 in. diameter Bolts
ZparZs-perZm-per ZparZs-perZm-per ZparZs-perZm-per
Douglas Fir-Larch176010401190240011701580409013502480
Douglas Fir-Larch (North)174010301170238011301550405012902370
Douglas Fir-South16609401110228010401480386012002200
Hem-Fir1590840105021909201400360010801980
Hem-Fir (North)16609401110228010401480386012002200
Spruce-Pine-Fir1570830104021609001380353010501930
Spruce-Pine-Fir (South)14306609201990720123030408401540
Southern Pine187011301290255013301690431015302700

Notes:

1. Member thickness is measured parallel to the axis of the fastener.

2. Designations for lateral design values are as illustrated: (a) Zpar for both members with direction of grain parallel to load; (b) Zs-per for side member with grain perpendicular to load and main member with grain parallel to load; and (c) Zm-per for main member with grain perpendicular to load and side member with grain parallel to load. A fourth possibility, with both members having grain perpendicular to the direction of load, is rarely encountered and not included here. The official designations also shown below the illustrations contain "parallel" and "perpendicular" symbols instead of the abbreviations, "par" and "per" used in these tables and text.


Table A-3.28: Lateral design value, Z (lb) for bolts: double-shear connections, with two 1/4 in. A36 steel side plates1

A. Designation for double-shear lateral design values according to direction of grain2
 
lateral design value diagrams
B. 1-1/2 in. main member thickness
Species or Species Combination 1/2 in. diameter Bolts3/4 in. diameter Bolts1 in. diameter Bolts
ZparZper ZparZper ZparZper
Douglas Fir-Larch105047015805902100680
Douglas Fir-Larch (North)103046015505602060650
Douglas Fir-South97042014505201930600
Hem-Fir90038013504601800540
Hem-Fir (North)97042014505201930600
Spruce-Pine-Fir88037013204501760530
Spruce-Pine-Fir (South)76029011403601520420
Southern Pine115055017306602310770
C. 3-1/2 in. main member thickness
Species or Species Combination 1/2 in. diameter Bolts3/4 in. diameter Bolts1 in. diameter Bolts
ZparZper ZparZper ZparZper
Douglas Fir-Larch165010303340137040901580
Douglas Fir-Larch (North)164010103320131048101510
Douglas Fir-South15909703220121045101400
Hem-Fir15408903120108042001260
Hem-Fir (North)15909703220121045101400
Spruce-Pine-Fir15308603080105041101230
Spruce-Pine-Fir (South)143068026608403540980
Southern Pine172011003480155053801790
D. 5-1/2 in. main member thickness
Species or Species Combination 5/8 in. diameter Bolts3/4 in. diameter Bolts1 in. diameter Bolts
ZparZper ZparZper ZparZper
Douglas Fir-Larch241014203340189057202480
Douglas Fir-Larch (North)239014003320185056702370
Douglas Fir-South233013403220178055102200
Hem-Fir226012803120169053301980
Hem-Fir (North)233013403220178055102200
Spruce-Pine-Fir223012703090165052801930
Spruce-Pine-Fir (South)209011402890132049301540
Southern Pine251015103480200059602810

Notes:

1. Member thickness is measured parallel to the axis of the fastener.

2. Designations for lateral design values are as illustrated: (a) Zpar for main member with direction of grain parallel to load; and (b) Zper for main member with grain perpendicular to load. The official designations also shown below the illustrations contain "parallel" and "perpendicular" symbols instead of the abbreviations, "par" and "per" used in these tables and text.


Table A-3.29: Lateral design value, Z (lb) for lag screws: single-shear connections, both members same species (or same specific gravity)1,2,3,4

A. Designation for single-shear lateral design values according to direction of grain2
 
lateral design value diagrams
B. 1-1/2 in. side member thickness
Species or Species Combination 1/2 in. diameter
Lag Screws
3/4 in. diameter
Lag Screws
1 in. diameter
Lag Screws
ZparZs-perZm-per ZparZs-perZm-per ZparZs-perZm-per
Douglas Fir-Larch3902202707704405101290530810
Douglas Fir-Larch (North)3902202607604305101280500790
Douglas Fir-South3702102507304004801230470760
Hem-Fir3501902407003604501180420720
Hem-Fir (North)3702102507304004801230470760
Spruce-Pine-Fir3501902406903504401160410710
Spruce-Pine-Fir (South)3101602106202803901070330630
Southern Pine4102502908304705601360 600870
C. 3-1/2 in. side member thickness
Species or Species Combination 1/2 in. diameter
Lag Screws
3/4 in. diameter
Lag Screws
1 in. diameter
Lag Screws
ZparZs-perZm-per ZparZs-perZm-per ZparZs-perZm-per
Douglas Fir-Larch39027027096060061017408501060
Douglas Fir-Larch (North)39026026095058060017308301040
Douglas Fir-South38025025092055058016707901000
Hem-Fir3602402408905005501610740950
Hem-Fir (North)38025025092055058016707901000
Spruce-Pine-Fir3602402408804905401600720940
Spruce-Pine-Fir (South)3402202208204204901450630850
Southern Pine410290 2901010650 65018309301120

Notes:

1. Member thickness is measured parallel to the axis of the fastener.

2. Designations for lateral design values are as illustrated: (a) Zpar for both members with direction of grain parallel to load; (b) Zs-per for side member with grain perpendicular to load and main member with grain parallel to load; and (c) Zm-per for main member with grain perpendicular to load and side member with grain parallel to load. A fourth possibility, with both members having grain perpendicular to the direction of load, is rarely encountered and not included here. The official designations also shown below the illustrations contain "parallel" and "perpendicular" symbols instead of the abbreviations, "par" and "per" used in these tables and text.

3. Tabular values are based on full value minimum penetration, p, into main member. For penetration into main member between 4D and 8D, multiply tabular values by p/(8D).

4. The reduced body diameter, Dr, is used in yield limit calculations for these lag screw lateral design values, except in the calculation of the dowel bearing strength for loading perpendicular to grain, Fe-perp, in which case the nominal diameter, D, is used.


Table A-3.30: Lateral design value, Z (lb) for common lails: single-shear connections, both members same species (or same specific gravity)1,2,4

A. 3/4 in. side member thickness
Species or Species Combination Nail Size (pennyweight)
6d8d10d12d16d20d30d40d50d
Douglas Fir-Larch7290105105121138147158162
Douglas Fir-Larch (North)7187102102117134143154158
Douglas Fir-South65809494108125133144147
Hem-Fir5873858599114122132136
Hem-Fir (North)65809494108125133144147
Spruce-Pine-Fir5770838396111119 129132
Spruce-Pine-Fir (South)465869698093101110113
Southern Pine79104121121138157166178182
B. 1-1/2 in. side member thickness
Species or Species Combination Nail Size (pennyweight)
6d8d10d12d16d20d30d40d50d
Douglas Fir-Larch397118118141170186205211
Douglas Fir-Larch (North)395115115138166182201206
Douglas Fir-South390109109131157172190196
Hem-Fir384102102122147161178181
Hem-Fir (North)390109109131 157172 190196
Spruce-Pine-Fir382100100120144158172175
Spruce-Pine-Fir (South)3728787104126131138141
Southern Pine3106128128154185203224230

Notes:

1. Member thickness is measured parallel to the axis of the fastener.

2. Where values are not indicated, nail penetration into main member does not satisfy minimum requirements. Otherwise, except as indicated in Note 3, it is assumed that the minimum penetration of the nail into the main member is equal to 10D (see Appendix Table A-3.19 for notes on penetration).

3. These values must be reduced according to Note 3 in Appendix Table A-3.19, since the penetration falls below the minimum for full value. Nail dimensions can be found in Appendix Table A-3.18.

4. In all cases where yield limit equations are used to compute lateral design values for nails, the dowel bearing length in the main member, lm, is taken as the penetration minus half the length of the tapered tip. Because these tabular lateral design values do not consider this reduced dowel bearing length, they may be slightly non-conservative in some cases (specifically, they may differ in cases where the governing yield limit equation includes the dowel bearing length parameter).


Table A-3.31: Method for determining lateral design value, Z, based on yield limit equations

For wood-wood or wood-metal connections that do not correspond to the parameters listed in the various Appendix tables, lateral design values may be determined using yield limit equations.
 
1. Using Appendix Table A-3.11 (specific gravity for wood members), find the specific gravity (G) for wood main and side member(s).
 
2. Find fastener diameter: use diameter, D, for bolts and nails (unthreaded shanks in contact with members) and reduced body diameter, Dr, for lag screws (in either case, designated as "D" in what follows);
 
3. Find dowel bearing strength, Fe, for main (Fem) and side (Fes) member(s), in psi units, using the appropriate specific gravity value for each wood member:
 
  a. For D > 0.25 in. and wood members loaded parallel to grain, Fe = 11,200G.
 
  equation
 
  c. For D ≤ 0.25 in. and wood members, Fe = 16,600G1.84.
 
  d. For A36 steel, Fe = 87,000.
 
  e. For A653 GR33 steel (used in certain die-formed galvanized connector plates), Fe = 61,850.
 
4. Find the dowel bending yield strength, Fyb, in psi units:
 
  a. For bolts, use Fyb = 45,000.
 
  b. For lag screws with D = 1/4 in., use Fyb = 70,000; with D = 5/16 in., use Fyb = 60,000; for D ≥ 3/8 in., use Fyb = 45,000.
 
  c. For nails with 0.099 in. ≤ D ≤ 0.142 in., use Fyb = 100,000; with 0.142 in. < D ≤ 0.177 in., use Fyb = 90,000;
    with 0.177 in. < D ≤ 0.236 in., use Fyb = 80,000; with 0.236 in. < D ≤ 0.273 in., use Fyb = 70,000;
 
5. Find the main member and side member dowel bearing lengths, lm and ls, in inches (see Appendix Table A-3.19 for guidance). Even where there are two side members, the side member bearing length only includes the bearing length in a single side member.
equation
 
7. Compute the "reduction term," Rd, which varies according to yield mode and fastener diameter, as follows:
 
  a. For D ≤ 0.17 in. (i.e., for nails 16d or smaller), Rd = 2.2.
 
  b. For 0.17 in. < D < 0.25 in. (i.e., for most nails larger than 16d), Rd = 10D + 0.5.
 
  c. For 0.25 in. ≤ D ≤ 1 in. (i.e., for most bolts and lag screws), Rd = 4Kθ (for yield modes Im and Is); Rd = 3.6Kθ (for yield mode II); and Rd = 3.2Kθ (for yield modes IIIm, IIIs, and IV). In these equations, Kθ = 1 + 0.25(θ/90), where θ = the maximum angle (degrees) between the load and the direction of grain for either member: for example, where the load is parallel to the direction of grain in all members, θ = 0 degrees, and Kθ = 1.0; where one or more member's grain is perpendicular to the load, θ = 90°, and Kθ = 1.25. For angles other than 0 or 90°, θ is always measured in such a way that it falls between 0 and 90 (i.e., instead of using θ = 120°, or θ = –45°, use θ = 60° or θ = 45°, respectively).
 
8. Compute the coefficients k1, k2, and k3, as follows:
 
  equation
 
9. Compute the lateral design value, Z, for all applicable yield modes (i.e., for all six modes in single shear, and for all modes except II and IIIm in double shear), and select the smallest value:
 
  equation


Table A-3.32: Withdrawal design value, W, per inch of penetration (lb) for lag screws1,2

Species or Species Combination Unthreaded shank diameter, D (in.)
1/45/163/87/161/25/83/47/81
Douglas Fir-Larch225266305342378447513576636
Douglas Fir-Larch (North)218258296332367434498559617
Douglas Fir-South199235269302334395453508562
Hem-Fir179212243273302357409459508
Hem-Fir (North)199235269302334395453508562
Spruce-Pine-Fir173205235264291344395443490
Spruce-Pine-Fir (South)137163186209231273313352389
Southern Pine260307352395437516592664734

Notes:

1. Penetration length for lag screws excludes tapered tip; see Appendix Table A-3.17 for dimensions, and Appendix Table A-3.19 for notes on penetration.

2. Withdrawal design values assume penetration into side grain of wood member, and must be reduced by 75% when inserted into end grain.

 
 

Table A-3.33: Withdrawal design value, W, per inch of penetration (lb) for nails1,2

Species or Species Combination Nail size (pennyweight)
6d8d10d12d16d20d30d40d50d
Douglas Fir-Larch283236364047505560
Douglas Fir-Larch (North)263034343845485257
Douglas Fir-South222629293238414548
Hem-Fir192225252732353841
Hem-Fir (North)22262929323841 4548
Spruce-Pine-Fir182123232630333538
Spruce-Pine-Fir (South)121416161721222426
Southern Pine354146465059647076

Notes:

1. Penetration length for nails includes tapered tip; see Appendix Table A-3.18 for dimensions, and Appendix Table A-3.19 for notes on penetration.

2. Withdrawal design values assume penetration into side grain of wood member. Nails subject to withdrawal are not permitted to be inserted into end grain of wood member.