Lumber Siding

Shearwalls

SDPWS / ASCE 7

Major References

-

SDPWS Table 4.3D, SDPWS 4.3.7.7-10

Wall Construction

(for more details, see table for Wall Construction)

Siding Thickness

¾”

1” nominal

Siding Width

Not included*

6 inches or less; 8 inches or greater.

Orientation

Horizontal, Vertical, Diagonal, or Dbl. Diag.

Horizontal, Vertical, Diagonal, or Double diagonal

Sheathing surface

Either, Both

Either or both

Plies

Via Orientation input

1 or 2 (Double Diagonal)

Blocking (vertical)

Blocked

"Applied to studs and blocking"

All others

Unblocked and disabled

Doesn't say (not needed)

Stud Spacing

12,16,24

Doesn’t say

* The siding width can be inferred by the number of nails selected.

Fasteners per board

Nail Type

Location

Board Width

Nails per board

Common

Edge

6"

3

3

Common

Edge

8"

4

4

Common

Field

6"

2

2

Common

Field

8"

3

3

Box

Edge

6"

5

5

Box

Edge

8"

6

6

Box

Field

6"

3

3

Box

Field

8"

4

4

Fastener Types and Sizes

Common Nails

8d,10d,12d

8d

Box Nails

8d,10d,12d

8d

ASD Shear Capacities

Shearwalls

SDPWS Table 4.3D

Sheathing Orientation

Wind

Seismic

Unfactored for ASD

Horizontal

70

50

140

Single diagonal

420

300

840

Double Diagonal

840

600

1680

Vertical

62.5

44.6

125

Shear Capacity Adjustments

Reference

SDPWS Table 4.3D

ASD Reduction Factor

Incorporated into design values

SDPWS 4.1.4

Wind design

2.0

2.0

Seismic design

2.8

2.8

Note for ASD Factor

No note

Note 1 referring to 4.1.4

Specific gravity factor

None

None

Unblocked Factor

None

None

Aspect Ratio Factor

None

None

Perforated Wall Factor Co

Lumber siding only allowed in combination with wood structural panels on perforated walls; refer to Wood Structural Panel Provisions

Seismic Information

Allowable Design Categories

ASCE-7 Table 12.2-1, SDPWS 4.3.7.7-10

Diagonal or Double DIagonal

35 feet or less

Sets capacity to 0 for E, F

Allows A, B, C, D

35 Feet or less

Sets capacity to 0 for E, F

Allows A, B, C, D

Vertical or horizontal

Sets capacity to 0 for D, E, F

Allows A, B, C

Response modification factor R

Input in Site Dialog, Prompts to change upon load generation

ASCE-7 Table 12.2-1, 12.8.1.1

R -bearing walls

Default 2.0

2.0

R -building frames

Default 2.5

2.5

Deflection amplification factor C_d

Input in Site Dialog, Prompts to change upon load generation

ASCE-7 Table 12.2-1,

12.8.6

C_d - bearing walls

Default 2.0

2.0

C_d - building frames

Default 2.5

2.5

Overstrength Factor W₀*

Cannot be overriden

ASCE-7 Table 12.2-1, inc. note b; 12.10.1.1.

W₀ - bearing walls, rigid diaphragms

2.5

2.5

W₀ - building frames, rigid diaphragms

2.5

2.5

W₀ - bearing walls, flexible diaphragms

2.0

2.0 or 2.5

W₀ - building frames, flexible diaphragms

2.0

2.0 or 2.5

*for drag strut force from discontinuous shear lines above, only

Use "shear panels with all other materials category" for R, , C_d , and W₀*

Permissible Force Distribution Method

Refer to Shear Force Distribution Methods for more a description of these methods and how they are selected.

Reference

SDPWS 4.3.5.5.1

Deflection-based distribution

Allowed

Allowed

Capacity-based distribution

Contribution of lumber siding is ignored for seismic design

Not allowed

Aspect Ratio

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.

Maximum aspect ratio

4.3.3, Table 4.3.3, Table 4.3.3 Note 2

Vertical, Horizontal

2:1*

Doesn't say

Diagonal

2:1

2:1

Double diagonal

3.5:1**

Refers to "regular" diagonal for 2:1 ratio.

*Use value for single diagonal in absence of guidance for horizontal and vertical lumber siding

**Use value for wood structural panels in absence of guidance for double-diagonal.

Combination of Sheathing Capacities

For more details, refer to Combination of Sheathing Capacities,

Reference

SDPWS 4.3.3.3

Lumber siding with same orientation and nailing details on both sides

Add capacities

Add capacities

Lumber siding with different orientation or nailing details on other side

V_wc =K_min G_ac

V_wc =K_min G_ac

With different orientation of lumber siding on other side, seismic

V_sc =K_min G_ac

V_sc =K_min G_ac

With non-lumber siding on other side

twice weakest or strongest

twice weakest or strongest

With wood structural panels on other side, wind

Add capacities

Add capacities

Sheathing Bending Capacities

Reference

All types – 3/4"

From WFCM Table 3A

Not included in SPDWS Table 3.2.1,

included in WFCM Table 3A