The table below lists the design code provisions applicable to design for lumber siding from pecial Design Provisions for Wind and Seismic (SDPWS) and the ASCE 7. One column is for the design code provision, the other is for the implementation in Shearwalls; in most cases they are the same.
For some provisions, more detailed information is found in a table dedicated to the provision in another topic that is cross-referenced in this table.
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Lumber Siding |
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Shearwalls |
SDPWS / ASCE 7 |
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Major References |
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SDPWS Table 4.3D, SDPWS 4.3.7.7-10 |
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Wall Construction |
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(for more details, see table for Wall Construction) |
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Siding Thickness |
¾” |
1” nominal |
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Siding Width |
Not included* |
6 inches or less; 8 inches or greater. |
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Orientation |
Horizontal, Vertical, Diagonal, or Dbl. Diag. |
Horizontal, Vertical, Diagonal, or Double diagonal |
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Sheathing surface |
Either, Both |
Either or both |
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Plies |
Via Orientation input |
1 or 2 (Double Diagonal) |
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Blocking (vertical) |
Blocked |
"Applied to studs and blocking" |
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All others |
Unblocked and disabled |
Doesn't say (not needed) |
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Stud Spacing |
12,16,24 |
Doesn’t say |
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* The siding width can be inferred by the number of nails selected. |
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Fasteners per board |
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Nail Type |
Location |
Board Width |
Nails per board |
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Common |
Edge |
6" |
3 |
3 |
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Common |
Edge |
8" |
4 |
4 |
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Common |
Field |
6" |
2 |
2 |
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Common |
Field |
8" |
3 |
3 |
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Box |
Edge |
6" |
5 |
5 |
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Box |
Edge |
8" |
6 |
6 |
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Box |
Field |
6" |
3 |
3 |
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Box |
Field |
8" |
4 |
4 |
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Fastener Types and Sizes |
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Common Nails |
8d,10d,12d |
8d |
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Box Nails |
8d,10d,12d |
8d |
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ASD Shear Capacities |
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Shearwalls |
SDPWS Table 4.3D |
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Sheathing Orientation |
Wind |
Seismic |
Unfactored for ASD |
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Horizontal |
70 |
50 |
140 |
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Single diagonal |
420 |
300 |
840 |
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Double Diagonal |
840 |
600 |
1680 |
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Vertical |
62.5 |
44.6 |
125 |
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Shear Capacity Adjustments |
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Reference |
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SDPWS Table 4.3D |
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ASD Reduction Factor |
Incorporated into design values |
SDPWS 4.1.4 |
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Wind design |
2.0 |
2.0 |
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Seismic design |
2.8 |
2.8 |
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Note for ASD Factor |
No note |
Note 1 referring to 4.1.4 |
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Specific gravity factor |
None |
None |
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Unblocked Factor |
None |
None |
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Aspect Ratio Factor |
None |
None |
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Perforated Wall Factor Co |
Lumber siding only allowed in combination with wood structural panels on perforated walls; refer to Wood Structural Panel Provisions |
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Seismic Information |
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Allowable Design Categories |
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ASCE-7 Table 12.2-1, SDPWS 4.3.7.7-10 |
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Diagonal or Double DIagonal |
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35 feet or less |
Sets capacity to 0 for E, F |
Allows A, B, C, D |
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35 Feet or less |
Sets capacity to 0 for E, F |
Allows A, B, C, D |
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Vertical or horizontal |
Sets capacity to 0 for D, E, F |
Allows A, B, C |
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Response modification factor R |
Input in Site Dialog, Prompts to change upon load generation |
ASCE-7 Table 12.2-1, 12.8.1.1 |
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R -bearing walls |
Default 2.0 |
2.0 |
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R -building frames |
Default 2.5 |
2.5 |
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Deflection amplification factor Cd |
Input in Site Dialog, Prompts to change upon load generation |
ASCE-7 Table 12.2-1, 12.8.6 |
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Cd - bearing walls |
Default 2.0 |
2.0 |
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Cd - building frames |
Default 2.5 |
2.5 |
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Overstrength Factor W0* |
Cannot be overriden |
ASCE-7 Table 12.2-1, inc. note b; 12.10.1.1. |
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W0 - bearing walls, rigid diaphragms |
2.5 |
2.5 |
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W0 - building frames, rigid diaphragms |
2.5 |
2.5 |
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W0 - bearing walls, flexible diaphragms |
2.0 |
2.0 or 2.5 |
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W0 - building frames, flexible diaphragms |
2.0 |
2.0 or 2.5 |
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*for drag strut force from discontinuous shear lines above, only |
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Use "shear panels with all other materials category" for R, , Cd , and W0* |
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Permissible Force Distribution Method |
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Refer to Shear Force Distribution Methods for more a description of these methods and how they are selected. |
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Reference |
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SDPWS 4.3.5.5.1 |
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Deflection-based distribution |
Allowed |
Allowed |
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Capacity-based distribution |
Contribution of lumber siding is ignored for seismic design |
Not allowed |
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Aspect Ratio |
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Aspect ratio = h/b, b = segment length, h = height, applies to wall segments or FTAO piers. For more details see Aspect Ratio Limits and Factors. |
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Maximum aspect ratio |
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4.3.3, Table 4.3.3, Table 4.3.3 Note 2 |
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Vertical, Horizontal |
2:1* |
Doesn't say |
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Diagonal |
2:1 |
2:1 |
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Double diagonal |
3.5:1** |
Refers to "regular" diagonal for 2:1 ratio. |
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*Use value for single diagonal in absence of guidance for horizontal and vertical lumber siding |
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**Use value for wood structural panels in absence of guidance for double-diagonal. |
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Combination of Sheathing Capacities |
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For more details, refer to Combination of Sheathing Capacities, |
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Reference |
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SDPWS 4.3.3.3 |
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Lumber siding with same orientation and nailing details on both sides |
Add capacities |
Add capacities |
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Lumber siding with different orientation or nailing details on other side |
Vwc =Kmin Gac |
Vwc =Kmin Gac |
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With different orientation of lumber siding on other side, seismic |
Vsc =Kmin Gac |
Vsc =Kmin Gac |
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With non-lumber siding on other side |
twice weakest or strongest |
twice weakest or strongest |
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With wood structural panels on other side, wind |
Add capacities |
Add capacities |
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Sheathing Bending Capacities |
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Reference |
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All types – 3/4" |
From WFCM Table 3A |
Not included in SPDWS Table 3.2.1, included in WFCM Table 3A |
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