HEADER DESIGN PER 2015 WFCM ENGINEERED AND PRESCRIPTIVE PROVISIONS (STD343)  John “Buddy” Showalter, P.E. Vice President, Technology Transfer American Wood Council   Description The 2015 Wood Frame Construction Manual (WFCM) is referenced in the 2015 International Building Code and 2015 International Residential Code. For WFCM load calculations, Minimum Design Loads for Buildings and Other Structures (ASCE 7-10) is used. The 2015 WFCM includes design information for wind and seismic loads and gravity loads including snow, roof live, floor live, and dead loads on buildings up to 3 stories. This presentation will provide background and examples for calculation of forces on headers which will enable designers and code officials to quickly determine design loads. It will also provide engineered prescriptive solutions for both solid sawn and glued-laminated timber headers to resist those loads. Related issues including jack studs, king studs, connections for lateral and gravity loads, and the difference between dropped and raised headers will be discussed. Learning Objectives Upon completion of this webinar, participants will:

1. Understand applicable lateral and gravity loads from ASCE 7-10 for headers within the WFCM scope.

2. Be familiar with the difference between dropped and raised headers. 3. Be familiar with the design of jack studs and king studs to resist both gravity and lateral loads. 4. Be familiar with the design of lateral, shear, gravity, and uplift connections related to headers.

   

This presentation is protected by US and International Copyright laws. Reproduction, distribution, display and use of the presentation without written permission of AWC is

prohibited.

© American Wood Council 2017

• The American Wood Council is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES), Provider # 50111237.

• Credit(s) earned on completion of this course will be reported to AIA CES for AIA members. Certificates of Completion for both AIA members and non-AIA members are available upon request.

• This course is registered with AIA CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product.

• Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.

2

Polling Question

1) What is your profession?

a) Architect/Building Designer

b) Engineer

c) Code Official

d) Builder

e) Other

3

Course Outline

Background on Design Loads – Wind and Gravity

Engineered Provisions – Calculating Design Loads

Prescriptive Provisions – Wood Frame Solutions

Design Examples

Reference Material

4

Reference Codes and Standards

2001 WFCM → 2003, 2006, 2009 IRC/IBC

2012 WFCM → 2012 IRC/IBC

2015 WFCM → 2015 IRC/IBC

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ASCE 7-10 → 2015 WFCM

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WFCMWood Frame Construction Manual for One- and Two-Family Dwellings

COMMENTARY2015 EDITION

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C1.1 Scope

C1.1.1 General

The scope statement limits applicability of the provi-sions of the Wood Frame Construction Manual to one- and two-family dwellings. This limitation is related primarily to assumed design loads and to structural configurations. Code prescribed floor design loads for dwellings gener-ally fall into the range of 30 to 40 psf, with few additional requirements such as concentrated load provisions. In these applications, use of closely spaced framing members covered by structural sheathing has proven to provide a reliable structural system.

C1.1.2 Design Loads

Unless stated otherwise, all calculations are based on standard linear elastic analysis and Allowable Stress Design (ASD) load combinations using loads from ASCE 7-10 Minimum Design Loads for Buildings and Other Structures.Dead Loads

Unless stated otherwise, tabulated values assume the following dead loads: Roof 10 psf Ceiling 5 psf Floor 10 psf 12 psf (for Seismic) Walls 11 psf Partitions 8 psf (for Seismic)

Live LoadsUnless stated otherwise, tabulated values assume the

following live loads: Roof 20 psf Floor (sleeping areas) 30 psf Floor (living areas) 40 psf

Wind LoadsWind forces are calculated assuming a “box-like”

structure with wind loads acting perpendicular to wall and roof surfaces. Lateral loads flow into roof and floor diaphragms and are transferred to the foundation via shear walls. Roof uplift forces are transferred to the foundation by direct tension through the wall framing and tension straps or wall sheathing. Shear wall overturning forces are resisted by the structure’s dead load and by supplemental hold down connections.

Implicit in the assumption of a “box-like” structure is a roughly rectangular shape, relatively uniform distri-bution of shear resistance throughout the structure, and

no significant structural discontinuities. In addition, the buildings are assumed to be enclosed structures in which the structural elements are protected from the weather. Partially enclosed structures are subjected to loads that require further consideration.

For wind load calculations, ASCE 7-10 is used. ASCE 7-10 calculations are based on 700-year return period “three second gust” wind speeds corresponding to an ap-proximate 7% probability of exceedence in 50 years, and use combined gust and pressure coefficients to translate these wind speeds into peak design pressures on the struc-ture. The 2015 WFCM includes design information for buildings located in regions with 700-year return period “three second gust” design wind speeds between 110 and 195 mph. Basic Design Equations:

ASD wind pressures, pmax, for Main Wind-Force Re-sisting Systems (MWFRS) and Components and Cladding (C&C) are computed by the following equations, taken from ASCE 7-10:

MWFRS – Envelope Procedure:

pmax = q[(GCpf) – (GCpi )] (lbs/ft2)where:

q = 0.60 qh

qh = 0.00256KzKztKdV2 (ASCE 7-10 Equation 28.3-1)

GCpf = external pressure coefficients (ASCE 7-10 Figure 28.4-1)

GCpi = internal pressure coefficients (ASCE 7-10 Table 26.11-1)

C&C: pmax = q[(GCp) – (GCpi)] (lbs/ft2)where:

q = 0.60qh

qh = 0.00256KzKztKdV2 (ASCE 7-10 Equation 30.3-1)

GCp = external pressure coefficients (ASCE7-10 Figures 30.4-1,30.4-2A, B, &C)

GCpi = internal pressure coefficients (ASCE 7-10 Table 26.11-1)

The calculation of ASD velocity pressure, q, for various wind speeds and Exposures is shown in Table C1.1.

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Table C1.1 ASD Velocity Pressure, q (psf), for Exposures B, C, and D and 33' MRH

Exposure Category

ASD Velocity Pressure, q(psf)

700-yr. Wind Speed 3-second gust (mph)110 115 120 130 140 150 160 170 180 195

Exposure B 11.37 12.43 13.54 15.89 18.42 21.15 24.06 27.17 30.46 35.74Exposure C 15.80 17.27 18.80 22.06 25.59 29.38 33.42 37.73 42.30 49.65Exposure D 18.64 20.37 22.18 26.04 30.20 34.66 39.44 44.52 49.92 58.58

q = 0.6 qh

qh = 0.00256 Kz Kzt Kd V2

and Kz (33 ft) = 0.72 ASCE 7-10 Table 28.3-1 (MWFRS), Table 30.3-1(C&C) at mean roof height (MRH) of 33 ft

Kzt = 1.0 No topographic effects

Kd = 0.85 ASCE 7-10 Table 26.6-1

Design wind pressures in ASCE 7-10 are based on an ultimate 700-year return period. Since the WFCM uses al-lowable stress design, forces calculated from design wind pressures are multiplied by 0.60 in accordance with load combination factors per ASCE 7-10.

For example, the ASD velocity pressure, q, at 150 mph for Exposure B is calculated as follows:

q = 0.6 (0.00256)(0.72)(1.0)(0.85)(150)2 (lbs/ft2)

= 21.15 (lbs/ft2)

Note that the worst case of internal pressurization is used in design. Internal pressure and internal suction for MWFRS are outlined in WFCM Tables C1.3A and C1.3B, respectively. Pressure coefficients and loads for wind parallel and perpendicular to ridge are tabulated. Parallel to ridge coefficients are used to calculate wind loads acting perpendicular to end walls. Perpendicular-to-ridge coefficients are used to calculate wind loads acting perpendicular to side walls.

Pressures resulting in shear, uplift, and overturning forces are applied to the building as follows:Shear Calculations

The horizontal component of roof pressures is applied as a lateral load at the highest ceiling level (top of the up-permost wall).

Windward and leeward wall pressures are summed and applied (on a tributary area basis) as lateral loads at each horizontal diaphragm. For example, in typical two story construction, one-half of the height of the top wall goes to the roof or ceiling level, a full story height goes to

intermediate floor diaphragms (one-half from above and one-half from below) and one-half of the bottom story goes directly into the foundation.

Lateral roof and wall pressures for determining diaphragm and shear wall loads are calculated using en-veloped MWFRS coefficients. Spatially-averaged C&C coefficients are used for determining lateral framing loads, suction pressures on wall and roof sheathing, and exterior stud capacities.Uplift Calculations

Uplift for roof cladding is calculated using C&C loads. Uplift connections for roof framing members are calculat-ed using enveloped MWFRS loads. The rationale for using MWFRS loads for computing the uplift of roof assemblies recognizes that the spatial and temporal pressure fluctua-tions that cause the higher coefficients for components and cladding are effectively averaged by wind effects on different roof surfaces. The uplift load minus sixty percent of the roof and/or ceiling dead load is applied at the top of the uppermost wall. As this load is carried down the wall, the wall dead load is included in the analysis. The dead load from floors framing into walls is not included, in order to eliminate the need for special framing details where floors do not directly frame into walls.Overturning Calculations

Overturning of the structure as a result of lateral loads is resisted at the ends of shear walls in accordance with general engineering practice, typically with hold downs or other framing anchorage systems. In the WFCM, overturn-ing loads are differentiated from uplift loads. Overturning moments result from lateral loads which are resisted by

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GENERAL INFORMATION

AMERICAN WOOD COUNCIL

shear walls. Uplift forces arise solely from uplift on the roof, and are transferred directly into the walls supporting the roof framing.

ASCE 7-10 requires checking the MWFRS with a minimum 5 psf ASD lateral load on the vertical projected area of the roof and a 10 psf ASD lateral load on the wall. The 2015 WFCM incorporates this design check.Snow Loads

The 2015 WFCM includes design information for snow loads in accordance with ASCE 7-10 for buildings located in regions with ground snow loads between 0 and 70 psf. Both balanced and unbalanced snow load condi-tions are considered in design. Seismic Loads

The 2015 WFCM includes seismic design information in accordance with ASCE 7-10 for buildings located in Seismic Design Categories A-D, as defined by the 2015 IRC.C1.1.2.1 Torsion

Design for torsion is outside the scope of this docu-ment.C1.1.2.2 Sliding Snow

Design for sliding snow is outside the scope of this document.

C1.1.3 Applicability

C1.1.3.1 Building Dimensions a. Mean Roof Height Building height restrictions

limit the wind forces on the structure, and also provide as-surance that the structure remains “low-rise” in the context of wind and seismic-related code requirements.

The tables in the WFCM are based on wind calcula-tions assuming a 33 ft mean roof height, (MRH). This assumption permits table coverage up to a typical 3-story building. Footnotes have been provided to adjust tabulated requirements to lesser mean roof heights.

b. Building Length and Width Limiting the maxi-mum building length and width to 80 feet is provided as a reasonable upper limit for purposes of tabulating require-ments in the WFCM.C1.1.3.2 Floor, Wall, and Roof Systems

See C2.1.3.2 (Floor Systems), C2.1.3.3 (Wall Sys-tems), and C2.1.3.4 (Roof Systems).

C1.1.4 Foundation Provisions

Design of foundations and foundation systems is outside the scope of this document.

C1.1.5 Protection of Openings

Wind pressure calculations in the WFCM assume that buildings are fully enclosed and that the building envelope is not breached. Interior pressure coefficients, GCpi, of +/-0.18 are used in the calculations per ASCE 7-10 Table 26.11-1. Penetration of openings (e.g. windows and doors) due to flying debris can occur in sites subject to high winds with a significant debris field. Where these areas occur, opening protection or special glazing requirements may be required by the local authority to ensure that the building envelope is maintained.

C1.1.6 Ancillary Structures

Design of ancillary structures is outside the scope of this document.

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Polling Question

2) The 0.6 adjustment to wind pressures in WFCM is based on which of the following?

a) Topographic effects

b) ASCE 7-10 load combinations

c) Converting ultimate to allowable stress design

d) All of the above

e) b) and c)

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WFCMWood Frame Construction Manual for One- and Two-Family Dwellings2015 EDITION

ANSI/AWC WFCM-2015Approval date October 10, 2014

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GENERAL INFORMATION

Table 1 Applicability Limitations

LimitationReferenceSection Figures

33' 1.1.3.1a 1.2

3 1.1.3.1aBuilding Length and Width 80' 1.1.3.1b

Load Type

Partition Dead LoadWall Assembly Dead LoadFloor Dead LoadRoof/Ceiling Assembly Dead LoadFloor Live LoadRoof Live LoadCeiling Live LoadGround Snow Load

Wind Load

Seismic Load

10 20 psf

110 195 mph wind speed(700 yr. return period, 3 second gust)

Exposure B, C, and D

Seismic Design Category (SDC)SDC A, B, C, D0, D1, and D2

0 25 psf30 40 psf20 psf

10 20 psf0 70 psf

LOAD ASSUMPTIONS(See Chapter 2 or Chapter 3 tables for load assumptions

applicable to the specific tabulated requirement)Load Assumption

0 8 psf of floor area11 18 psf

Mean Roof Height (MRH)

Number of Stories

BUILDING DIMENSIONS

Attribute

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ENGINEERED DESIGN

2.1 General Provisions 15

2.2 Connections 17

2.3 Floor Systems 19

2.4 Wall Systems 21

2.5 Roof Systems 23

List of Figures 26

List of Tables 61

WOOD FRAME CONSTRUCTION MANUAL

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Attribute LimitationReference Section Figures

Mean Roof Height (MRH) 33' 2.1.3.1 1.2

Number of Stories 3 1.1.3.1a  ‐Building Length and Width 80' 1.1.3.1b  ‐

Joist Span 26' 2.1.3.2a  ‐Joist Spacing 24" o.c. 2.1.3.2b  ‐Cantilevers ‐ Supporting loadbearing  d 2.1.3.2c 2.1a

Setbacks ‐ Loadbearing walls1 d 2.1.3.2d 2.1dI‐Joist Span 26' 2.1.3.2a  ‐I‐Joist Spacing 24" o.c. 2.1.3.2b  ‐Cantilevers  (see manufacturer) 2.3.2.6 2.4e, 2.9a, 

2.9bSetbacks (see manufacturer) 2.3.2.5 2.4dTruss Span 26' 2.1.3.2a  ‐Truss Spacing 24" o.c. 2.1.3.2b  ‐Cantilevers (see truss plans) 2.3.3.6 2.13a, 2.13bSetbacks (see truss plans) 2.3.3.5  ‐

Vertical Floor Offset1 df 2.1.3.2e 2.1i

Floor Diaphragm Aspect Ratio1  4:1 2.1.3.2f 2.1jFloor Diaphragm Openings Lesser of 12' or 50% of Building 

Dimension2.1.3.2g 2.1k

Loadbearing Wall Height 20' 2.1.3.3a  ‐Non‐Loadbearing Wall Height 20' 2.1.3.3a  ‐Wall Stud Spacing 24" o.c. 2.1.3.3b  ‐

Shear Wall Line Offset1 4' 2.1.3.3c 2.1l

Shear Wall Story Offset1 No offset unless per Exception 2.1.3.3dShear Wall Segment Aspect Ratio (see SDPWS ) 2.1.3.3e

Rafter Span (Horizontal Projection)2 26' 2.1.3.4a  ‐Rafter Spacing 24" o.c. 2.1.3.4b  ‐

Eave Overhang Length1 Lesser of 2' or rafter span/3 2.5.1.1.2 2.1fRoof Slope Flat ‐ 12:12 2.1.3.4d  ‐I‐Joist Span 26' 2.1.3.4a  ‐I‐Joist Spacing 24" o.c. 2.1.3.4b  ‐Eave Overhang Length (see manufacturer) 2.5.2.1.2  ‐Roof Slope Flat ‐ 12:12 2.1.3.4d  ‐Truss Span 60' 2.1.3.4a  ‐Truss Spacing 24" o.c. 2.1.3.4b  ‐Eave Overhang Length (see truss plans) 2.5.3.1  ‐Roof Slope Flat ‐ 12:12 2.1.3.4d  ‐

Rakes Overhang Length1 Lesser of 2' or purlin span/3 2.1.3.4c 2.1g

Roof Diaphragms Roof Diaphragm Aspect Ratio1  4:1 2.1.3.4e 2.1j

Wood Roof Trusses

Lumber Rafters

Wall Studs

Shear Walls

ROOF SYSTEMS

Wood I‐Joist Roof System

Building

2 For roof snow loads, tabulated spans are limited to 20 ft.

BUILDING DIMENSIONS

FLOOR SYSTEMS

Lumber Joists

Floor Diaphragms

WALL SYSTEMS

Wood I‐Joists

Wood Floor Trusses

1 See exceptions.

Table 2 Engineered Design Limitations

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2.1 General Provisions

Table 2.1.3.1 Adjustment for Wind Exposure and Mean Roof Height

Mean Roof Height (feet)

Exposure

B

Exposure

C

Exposure

D0-15 1.00 1.18 1.4320 1.00 1.25 1.5025 1.00 1.31 1.5630 1.00 1.36 1.6133 1.00 1.39 1.64

b. Framing Member Spacings Floor framing member spacings shall not exceed 24 inches on center for lumber joists, I-joists, and floor trusses.

c. Cantilevers Lumber floor joist cantilevers sup-porting loadbearing walls shall not exceed the depth, d, of the joists (see Figure 2.1a). Lumber floor joist cantilevers supporting non-loadbearing walls shall be limited to L/4 (see Figure 2.1b). I-joist cantilevers shall be in accordance with the manufacturer’s code evaluation report. Truss cantilevers shall be in accordance with the truss design/placement plans. Lumber joists, I-joists, and trusses shall be located directly over studs when used in cantilever conditions, unless the top plate is designed to carry the load.

EXCEPTION: Lumber floor joist cantilevers supporting loadbearing walls shall be permit-ted to exceed these limits when designed for the additional loading requirements, but in no case shall they exceed four times the depth (4d) of the member (see Figure 2.1c).

d. Setbacks Setbacks of loadbearing walls on lumber floor joist systems shall not exceed the depth, d, of the joists (see Figure 2.1d). Setbacks on I-joists shall be in accordance with the manufacturer’s code evaluation report. Setbacks on floor trusses shall be in accordance with the truss design/placement plans. Lumber joists, I-joists, and trusses shall be located directly over studs when used in setback conditions supporting loadbearing walls, unless the top plate is designed to carry the load.

EXCEPTION: Lumber floor joist setbacks supporting loadbearing walls shall be permit-

2.1.1 Engineered Requirements

The provisions of this Chapter provide minimum loads for the purpose of establishing specific resistance require-ments for buildings within the scope of this document. This Chapter includes the results of engineering calculations for specific structural elements, in specific configurations, under specific loads. The tabulated information does not represent a complete engineering analysis as would be performed by a registered professional engineer, but is expected to result in significant time-savings for the design professional.

2.1.2 Continuous Load Path

A continuous load path shall be provided to transfer all lateral and vertical loads from the roof, wall, and floor systems to the foundation.

2.1.3 Engineered Design Limitations

Wood-frame buildings built in accordance with this document shall be limited to the conditions of this section (see Table 2). Structural conditions not complying with this section shall be designed in accordance with accepted engineering practice.

2.1.3.1 Adjustment for Wind Exposure and Mean Roof Height

Tabulated wind requirements in this chapter are based on wind exposure category B and a mean roof height of 33 feet. The building shall neither exceed three stories nor a mean roof height of 33 feet, measured from average grade to average roof elevation (see Figure 1.2). Additional loads from habitable attics shall be considered for purposes of determining gravity and seismic loads. For buildings sited in exposure category C or D, wind-related tabulated values shall be increased in accordance with specific adjustments as provided in table footnotes or per Table 2.1.3.1.

2.1.3.2 Floor Systemsa. Framing Member Spans Single spans of floor

framing members shall not exceed 26 feet for lumber joists, I-joists, and floor trusses. Design spans shall consider both strength and serviceability limits. For serviceability, the computed joist deflection under live load shall not exceed L/360 (span divided by 360) or more stringent criteria as specified by the manufacturer.

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2.1.5.4 Floor and Roof Diaphragm Assemblies Design of horizontal diaphragm assemblies shall be

in accordance with the SDPWS.a. Maximum spans and allowable total uniform loads

for floor sheathing are specified in Table S-1 of the WFCM Supplement.

b. Allowable stress design (ASD) allowable uniform load capacities for wind design shall be determined from SDPWS Section 3.2.3 for roof sheathing by dividing the tabulated nominal uniform load capacities in Table 3.2.2 of SDPWS by an ASD reduction factor of 1.6, modified by applicable footnotes in SDPWS. Maximum spans and allowable total uniform loads for roof live and snow loads for roof sheathing are specified in Table S-2 of the WFCM Supplement.

c. ASD allowable unit shear capacities for horizontal diaphragm assemblies are determined from SDPWS Section 4.2 by dividing the tabulated nominal unit shear capacities in Tables 4.2A, B, and C of SDPWS by an ASD reduction factor of 2.0, modified by applicable footnotes in SDPWS.

d. For horizontal diaphragm assemblies sheathed with gypsum wallboard, the allowable unit shear capacity is specified in WFCM Supplement Table S-3.

2.2 Connections

2.1.5.5 Wall Assemblies Design of vertical wall assemblies shall be in accor-

dance with the NDS and SDPWS.a. ASD allowable uniform load capacities for wall

sheathing resisting out-of-plane wind loads shall be deter-mined from SDPWS Section 3.2.1 by dividing the tabulated nominal uniform load capacities in Table 3.2.1 of SDPWS by an ASD reduction factor of 1.6, modified by applicable footnotes in SDPWS.

b. ASD allowable unit shear capacities for shear wall assemblies are determined from SDPWS Section 4.3 by dividing the tabulated nominal unit shear capacities in Tables 4.3A, B, and C of SDPWS by an ASD reduction factor of 2.0, modified by applicable footnotes in SDPWS.

2.1.5.6 FastenersDesign of fasteners shall be in accordance with the

NDS. Reference lateral design values for common, box, or sinker steel wire nails are specified in the NDS Tables 11N, P, Q, and R. Reference withdrawal values for nails are specified in the NDS Table 11.2C.

2.2.1 Lateral Framing Connections

Adequate connections between roof, ceiling, wall, and floor assemblies shall be provided to transfer lateral forces acting perpendicular to the wall surface (see Figure 2.2a).

2.2.1.1 Wall Assembly to Roof, Ceiling, or Floor Assembly

Framing connections to transfer lateral loads from the wall framing into the roof, ceiling, or floor diaphragm assembly shall be in accordance with the lateral loads specified in Table 2.1.

2.2.1.2 Foundation Wall to Floor Assembly Framing connections to transfer lateral loads from the

foundation wall into the floor diaphragm assembly shall be in accordance with the foundation design.

2.2.2 Shear Connections

Adequate connections between roof, ceiling, wall, and floor assemblies shall be provided to transfer shear forces acting parallel to the wall surface (see Figure 2.2b).

2.2.2.1 Roof, Ceiling, or Floor Assembly to Wall Assembly

Connections to transfer shear loads from the roof, ceiling, or floor diaphragm assembly to the shear wall segments shall be in accordance with the shear loads cal-culated using Tables 2.5A and 2.5B for wind perpendicular and parallel to ridge respectively, or using Table 2.6 for seismic motion.

2.2.2.2 Wall Assembly to Wall Assembly Connections to transfer shear loads from a shear wall

segment above to a shear wall segment below shall be in accordance with the shear loads calculated using Tables 2.5A and 2.5B for wind perpendicular and parallel to ridge respectively, or using Table 2.6 for seismic motion.

2.2.2.3 Floor Assembly to Foundation Connections to transfer shear loads from the floor as-

sembly to the foundation shall be in accordance with the shear loads using Tables 2.5A and 2.5B for wind perpen-dicular and parallel to ridge respectively, or using Table 2.6 for seismic motion.

2.2.2.4 Wall Assembly to Foundation Connections to transfer shear loads from the wall as-

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shear loads calculated using Tables 2.5A and 2.5B for wind perpendicular and parallel to ridge respectively, or using Table 2.6 for seismic motion.

2.2.3 Wind Uplift Connections

Adequate connections shall be provided to transfer uplift forces acting away from the roof surface(s) (see Figure 2.2c).

2.2.3.1 Roof Assembly to Foundation Connections to transfer uplift loads from the roof as-

sembly to the foundation shall be in accordance with the uplift loads specified in Table 2.2A. A continuous load path shall be maintained with either a continuous con-nector from the roof to the foundation or with a series of connections creating a complete load path.

2.2.4 Overturning Resistance

Resistance to shear wall overturning shall be provided (see Figure 2.2d). The resisting dead load moment shall be calculated using no more than 60% of the design dead load.

2.2.4.1 Hold-downs Hold-downs to provide overturning restraint to shear

wall segments at each level shall be provided at the ends of shear walls and as required to develop the shear capacity of the wall segments in accordance with 2.4.4.2. A continu-ous load path from the hold-down to the foundation shall be maintained. Where a hold-down resists the overturning load from the story or stories above, the hold-down shall be sized for the required hold-down tension capacity at its level plus the required hold-down tension capacity of the story or stories above. Hold-downs used to resist both uplift and overturning shall be designed to resist the sum of the forces determined in accordance with 2.2.3 and 2.2.4.

2.2.5 Sheathing and Cladding Attachment

Adequate attachment of sheathing and cladding shall be provided to assure the transfer of specified loads into framing members.

2.2.5.1 Roof Sheathing Roof sheathing shall be attached to roof structural

members to resist the withdrawal loads (suction) specified in Table 2.4 and provide the roof diaphragm shear capacity required in 2.5.4.2.

2.2.5.2 Wall Sheathing Wall sheathing shall be attached to wall structural

members to resist the withdrawal loads (suction) specified in Table 2.4 and provide the shear wall capacity required

in 2.4.4.2.

2.2.5.3 Floor Sheathing Sheathing shall be attached to provide the floor dia-

phragm shear capacity required in 2.3.4.2.

2.2.6 Special Connections

2.2.6.1 Ridge Connections Connection loads at the roof ridge shall be in accor-

dance with the loads specified in Table 2.2B.

2.2.6.2 Jack Rafters Connection of the jack rafter to the wall shall be in

accordance with 2.2.3.1. Connection of the jack rafter to hip beam shall be in accordance with the loads specified in Table 2.2B.

2.2.6.3 Hip and Valley BeamsHip and valley beams do not require special uplift

connections when jack rafters are attached in accordance with 2.2.6.2.

2.2.6.4 Hip Trusses Gravity and uplift loads at the hip truss to girder truss

connection shall be in accordance with the loads specified in the truss design drawings.

2.2.6.5 Non-Loadbearing Exterior Wall Assemblies

Walls which support rake overhang outlookers or lookout blocks shall be connected to the foundation in accordance with the uplift loads specified in Table 2.2C (see Figure 2.1g and 2.1h). Walls which do not support the roof assembly need only resist an uplift load of 60 plf.

2.2.6.6 Wall Openings Connections to transfer lateral, shear, and uplift loads

around wall openings shall be in accordance with the loads specified in 2.2.1.1, 2.2.2, and 2.2.3.1 for loadbearing walls or 2.2.1.1, 2.2.2, and 2.2.6.5 for non-loadbearing walls. A continuous load path shall be maintained around the opening and to the foundation.

2.2.6.7 Thrust ConnectionConnection to transfer thrust loads in the lower third

of the attic space shall be in accordance with the thrust loads specified in Table 2.3.

2.2.6.8 Rake Overhang OutlookersRake overhang outlookers shall be connected to the

gable endwall in accordance with the uplift loads specified in Table 2.2C (see Figure 2.1g).

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Lateral, Shear, and Uplift Loads

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2.3.3.3 End Restraint Restraint against twisting shall be provided at the

end of each truss by fastening to a full-height rim, band joist, header, or other member or by using blocking panels between truss ends. Framing details (see Figure 2.15a) for end restraint shall be provided in a manner consistent with SBCA/TPI’s Building Component Safety Information (BCSI) – Guide to Good Practice for Handling, Installing, Restraining, & Bracing of Metal Plate Connected Wood Trusses, or ANSI/TPI 1, or 2.3.3.1.

2.3.3.4 Chord and Web Bracing Chord and web bracing shall be provided in a manner

consistent with the guidelines provided in BCSI, ANSI/TPI 1, or in accordance with 2.3.3.1, and the bracing require-ments specified in the construction design documents (see Figure 2.14).

2.3.3.5 Single or Continuous Floor Trusses Supporting Walls

Floor trusses shall be designed for any intermediate loads and supports as shown on the construction docu-ments and/or plans.

2.3.3.6 Cantilevered Trusses Cantilevered floor trusses shall be designed for all

anticipated loading conditions (see Figures 2.13a-b).

2.3.3.7 Floor Openings Framing around floor openings shall be designed

to transfer loads to adjacent framing members that are designed to support the additional concentrated loads. Fasteners, connections, and stiffeners shall be designed for the loading conditions.

2.3.4 Floor Sheathing

2.3.4.1 Sheathing Spans Floors shall be fully sheathed with sheathing capable

of resisting and transferring the applied gravity loads to

the floor framing members. Sheathing shall be continuous over two or more spans.

2.3.4.2 Shear Capacity Floor sheathing and fasteners shall be capable of re-

sisting the total shear loads calculated using Tables 2.5A and 2.5B for wind perpendicular and parallel to ridge respectively, or using Table 2.6 for seismic motion.

2.3.4.2.1 Diaphragm Chords Diaphragm chords shall be continuous for the full length of the diaphragm. Diaphragm members and chord splices shall be capable of resisting the chord forces, calculated by the following equation:

T vL=4

(2.3-1)

where: T = Chord force, lbs

v = Required unit shear capacity of the floor diaphragm, plf

L = Floor diaphragm dimension perpendicular to the lateral load, ft

2.3.4.3 Sheathing Edge Support Edges of floor sheathing shall have approved tongue-

and-groove joints or shall be supported with blocking, unless 1/4-inch minimum thickness underlayment or 1-1/2 inches of approved cellular or lightweight concrete is in-stalled, or unless the finish floor is of 3/4-inch wood strip.

2.3.5 Floor Diaphragm Bracing

At panel edges perpendicular to floor framing mem-bers, framing and connections shall be provided to transfer the lateral wind loads from the exterior wall to the floor diaphragm assembly in accordance with the requirements of Table 2.1 (see Figure 2.3).

2.4 Wall Systems

2.4.1 Exterior Walls

2.4.1.1 Wood Studs Exterior wall studs shall be in accordance with the

requirements of Table 2.9A or Table 2.10 for the wind loads specified. Exterior loadbearing studs shall be in accordance with the requirements of Table 2.9B or Table

2.11 for the gravity loads specified. Exterior loadbearing studs shall be designed to resist the uplift loads specified in Table 2.2A, independent of the requirements of Tables 2.9A, 2.9B, 2.10, and 2.11. Exterior non-loadbearing studs shall be designed to resist the rake overhang uplift loads specified in Table 2.2C.

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of studs shall not be located in the middle one-third of the stud length. Notches in the outer thirds of the stud length shall not exceed 25% of the actual stud depth. Bored holes shall not exceed 40% of the actual stud depth and the edge of the hole shall not be closer than 5/8-inch to the edge of the stud. Notches and holes shall not occur in the same cross-section (see Figure 3.3b).

EXCEPTION: Bored holes shall not exceed 60% of the actual stud depth when studs are doubled.

2.4.1.1.2 Stud Continuity Studs shall be continuous between horizontal supports, including but not limited to: girders, oor diaphragm assemblies, ceiling diaphragm assemblies, and roof diaphragm assemblies. Where attic

oor diaphragm or ceiling diaphragm assemblies are used to brace gable endwalls, the sheathing and fasteners shall be capable of resisting the minimum shear requirements of able 2.5C.

2.4.1.1.3 Corners Corner framing shall be capable of transferring axial tension and compression loads from the shear walls and the structure abo e, connecting adjoining walls, and pro iding adequate backing for the attachment of sheathing and cladding materials.

2.4.1.2 Top Plates Exterior stud walls shall be capped with a single or

double top plate with bearing capacity in accordance with able 2.9B, and bending capacity in accordance with able

2.11. op plates shall be tied at joints, corners, and inter-secting walls to resist and transfer lateral loads to the roof or oor diaphragm in accordance with the requirements of able 2.1. Double top plates shall be lap spliced and o erlap at corners and intersections with other exterior and interior loadbearing walls.

2.4.1.3 Bottom Plate Wall studs shall bear on a bottom plate with bearing

capacity in accordance with able 2.9B. he bottom plate shall not be less than 2 inch nominal thickness and not less than the width of the wall studs. Studs shall ha e full bear-ing on the bottom plate. Bottom plates shall be connected to transfer lateral loads to the oor diaphragm or foundation in accordance with the requirements of able 2.1. Bottom plates that are connected directly to the foundation shall ha e full bearing on the foundation.

2.4.1.4 Wall Openings Headers shall be pro ided o er all exterior wall open-

ings. Headers shall be supported by wall studs, jack studs, hangers, or framing anchors.

2.4.1.4.1 Headers Headers shall be in accordance

with the lateral capacity requirements of able 2.1 and the gra ity capacity requirements of able 2.11.

2.4.1.4.2 Studs Supporting Header Beams Wall and jack studs shall be in accordance with the same require-ments as exterior wall studs selected in 2.4.1.1. Wall and jack studs shall be designed for additional lateral and uplift loads from headers and window sill plates in accordance with able 2.1 and able 2.2A.

2.4.1.4.3 Window Sill Plates Window sill plates shall be in accordance with the lateral capacity requirements of

able 2.1.

2.4.2 Interior Loadbearing Partitions

2.4.2.1 Wood Studs Interior loadbearing studs shall be in accordance with

the requirements of able 2.9C or able 2.11 for gra ity loads.

2.4.2.1.1 Notching and Boring Notches in either edge of studs shall not be located in the middle one-third of the stud length. Notches in the outer thirds of the stud length shall not exceed 25% of the actual stud depth. Bored holes in interior loadbearing studs shall not exceed 40% of the actual stud depth and shall not be closer than 5/8-inch to the edge. Notches and holes shall not occur in the same cross-section (see Figure 3.3b).

EXCEPTION: Bored holes shall not exceed 60% of the actual stud depth when studs are doubled.

2.4.2.1.2 Stud Continuity Studs shall be continuous between horizontal supports, including but not limited to: girders, oor diaphragm assemblies, ceiling diaphragm assemblies, and roof diaphragm assemblies.

2.4.2.2 Top Plates Interior loadbearing partition walls shall be capped

with a single or double top plate with bearing capacity in accordance with able 2.9C, and bending capacity in ac-cordance with able 2.11. op plates shall be tied at joints, corners, and intersecting walls. Double top plates shall be lap spliced and o erlap at corners and at intersections with other exterior and interior loadbearing walls.

2.4.2.3 Bottom Plate Wall studs shall bear on a bottom plate with bearing

capacity in accordance with able 2.9C. he bottom plate shall not be less than 2 inch nominal thickness and not less than the width of the wall studs. Studs shall ha e full bearing on the bottom plate.

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2.4.2.4 Wall Openings Headers shall be pro ided o er all interior loadbearing

wall openings. Headers shall be supported by wall studs, jack studs, hangers, or framing anchors.

2.4.2.4.1 Headers Headers shall be in accordance with the load requirements of able 2.11.

2.4.2.4.2 Studs Supporting Header Beams Wall and jack studs shall be in accordance with the same require-ments as interior loadbearing wall studs selected in 2.4.2.1.

2.4.3 Interior Non-Loadbearing Partitions

2.4.3.1 Wood Studs Interior non-loadbearing studs shall be of adequate

size and spacing to carry the weight of the applied nish.2.4.3.1.1 Notching and Boring Notches in studs shall

not exceed 40% of the actual stud depth. Bored holes shall not exceed 60% of the actual stud depth and shall not be closer than 5/8-inch to the edge. Notches and holes shall not occur in the same cross-section.

2.4.3.2 Top Plates All interior non-loadbearing partitions shall be capped

with single or double top plates.

2.4.3.3 Bottom Plate Wall studs shall bear on at least one bottom plate.

2.4.4 Wall Sheathing

2.4.4.1 Sheathing Spans Exterior wall sheathing shall be capable of resisting

and transferring the wind suction loads speci ed in able 2.4 to the wall framing.

2.4.4.2 Shear WallsWalls parallel to the applicable wind load or seismic

motion shall pro ide the required shear resistance at each le el. he sum of the indi idual shear wall segment shear capacities shall meet or exceed the sum of shear loads collected by horizontal diaphragms abo e. otal shear loads shall be calculated using ables 2.5A and 2.5B for wind perpendicular and parallel to ridge respecti ely, or using able 2.6 for seismic motion. Design loads shall be distributed to the arious ertical elements of the seismic force-resisting system in the story under consideration, based on the relati e lateral stiffness of the ertical resist-ing elements and the diaphragm.

2.4.4.3 Sheathing Edge Support All shear wall sheathing edges shall be supported.

2.5 Roof Systems

2.5.1 Wood Rafter Systems

2.5.1.1 Rafters Rafters shall be in accordance with the maximum

spans (horizontal projection) as speci ed in ables 2.14A-D. he span of each rafter shall be measured along the horizontal projection of the rafter.

2.5.1.1.1 Jack Rafters Jack rafters shall be in accor-dance with 2.5.1.1.

2.5.1.1.2 Rafter Overhangs Rafter o erhangs shall not exceed the lesser of one-third of the rafter span or 2 feet (see Figure 2.1f).

2.5.1.1.3 Rake Overhangs Rake o erhang outlookers shall use continuous 2x4 purlins connected in accordance with 2.2.6.8. Rake o erhangs shall not exceed the lesser of one-half of the purlin length or 2 feet (see Figure 2.1g).

EXCEPTION: Rake o erhangs using lookout blocks shall not exceed 1 foot (see Figure 2.1h).

2.5.1.1.4 Notching and Boring Notches in the top or bottom edge of rafters shall not be located in the middle one-third of the rafter span. Notches in the outer thirds of the span shall not exceed one-sixth of the actual rafter depth. Where notches are made at the supports, they shall not exceed one-fourth the actual rafter depth. Bored holes are limited in diameter to one-third the actual rafter depth and the edge of the hole shall not be closer than 2 inches to the top or bottom edge of the rafter (see Figure 3.3a).

2.5.1.2 Bearing Rafters shall bear directly on beams, girders, ledgers,

or loadbearing walls or be supported by hangers or fram-ing anchors.

2.5.1.3 End Restraint Where the nominal depth-to-thickness ratio of a rafter

exceeds 3, restraint against twisting shall be pro ided at the end of each rafter by fastening to a rim board or by

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Polling Question

3) Load-bearing wall header connections are designed for which of the following loads?

a) Lateral

b) Shear

c) Uplift

d) All of the above

e) a) and c) only

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List of Tables

2.1 Lateral Framing Connection Loads from Wind ............................................................ 62

2.2A Uplift Connection Loads from Wind ........... 63

2.2B Ridge Connection Loads from Wind ........... 64

2.2C Rake Overhang Outlooker Uplift Connection Loads ........................................................... 65

2.3 Thrust Connection Loads............................. 66

2.4 Roof and Wall Sheathing Suction Loads ..... 67

2.5A Lateral Diaphragm Loads from Wind - Perpendicular to Ridge ................................ 68

2.5B Lateral Diaphragm Loads from Wind - Parallel to Ridge .......................................... 69

2.5C Lateral Diaphragm Loads from Wind - Parallel to Ridge (Attic/Floor/Ceiling) ........ 71

2.6 Lateral Loads from Seismic ......................... 73

2.7A Floor Joist Spans for 30 psf Live Load........ 74

2.7B Floor Joist Spans for 40 psf Live Load........ 75

2.7C Floor Joist Bearing Stresses for Floor Loads ........................................................... 76

2.8A Floor Framing Capacity Requirements for 30 psf Live Load .................................... 77

2.8B Floor Framing Capacity Requirements for 40 psf Live Load .................................... 78

2.9A Exterior Wall Stud Bending Stresses from Wind Loads .................................................. 80

2.9B Exterior Wall Stud Compression Stresses ... 82

2.9C Interior Loadbearing Wall Stud Compression Stresses from Live Loads ...... 84

2.10 Exterior Wall Induced Moments from Wind Loads .................................................. 85

2.11 Loadbearing Wall Loads from Snow or Live Loads ................................................... 86

2.12A1-2 Ceiling Joist Spans for 10 psf Live Load .... 87

2.12B1-2 Ceiling Joist Spans for 20 psf Live Load .... 89

2.13A1-2 Ceiling Joist Framing Capacity Requirements (without storage)................... 91

2.13B1-2 Ceiling Joist Framing Capacity Requirements (with limited storage) ........... 93

2.14A Rafter Spans for 20 psf Live Load............... 96

2.14B Rafter Spans for 30 psf Ground Snow Load ............................................................. 99

2.14C Rafter Spans for 50 psf Ground Snow Load ........................................................... 100

2.14D Rafter Spans for 70 psf Ground Snow Load ........................................................... 101

2.15A Roof Framing Capacity Requirements for 20 psf Roof Live Load ......................... 103

2.15B Roof Framing Capacity Requirements for 30 psf Ground Snow Load ................... 106

2.15C Roof Framing Capacity Requirements for 50 psf Ground Snow Load ................... 107

2.15D Roof Framing Capacity Requirements for 70 psf Ground Snow Load ................... 108

2.16 Ridge Beam Capacity Requirements for Interior Center Bearing Roof and Ceiling . 110

2.17 Hip and Valley Beam Capacity Requirements ..............................................111

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Table 2.1 Lateral Framing Connection Loads from Wind (For Roof-to-Plate, Plate-to-Plate, Plate-to-Stud, and Plate-to-Floor)

110 115 120 130 140 150 160 170 180 195

67 73 79 93 108 124 141 159 178 20979 87 94 111 129 148 168 190 212 24991 100 109 128 148 170 193 218 245 287103 112 122 144 167 191 218 246 275 323114 124 135 159 184 212 241 272 305 358124 136 148 174 201 231 263 297 333 391135 147 160 188 218 250 285 321 360 423

1

2

3

12 16 19.2 24 481.00 1.33 1.60 2.00 4.00

4

Tabulated framing loads assume a building located in Exposure B with a mean roof height of 33 feet.  For buildings located in other exposures, tabulated values shall be multiplied by the appropriate adjustment factor in Section 2.1.3.1.Tabulated framing loads are specified in pounds per linear foot of wall.  To determine connection requirements, multiply the tabulated unit lateral framing load by the multiplier from the table below corresponding to the spacing of the connection:

When calculating lateral loads for ends of headers, girders, and window sills, multiply the tabulated unit lateral load by ½ of the header, girder, or sill span (ft).

Connection Spacing (in.)Multiplier

Wall Height (ft)

810

Tabulated framing loads shall be permitted to be multiplied by 0.92 for framing not located within 3 feet of corners for buildings less than 30 feet in width (W), or within W/10 of corners for buildings greater than 30 feet in width.

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Unit Framing Loads (plf)1,2,3,4

1618

1214

700‐yr. Wind Speed 3‐second gust (mph)

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Table 2.1 Lateral Framing Connection Loads from Wind

Description: Lateral framing connection loads at base and top of wall expressed in pounds per linear foot of wall length.

Procedure: Compute the lateral framing connection load at the top and bottom of studs based on tributary wind loads, using external (end zone) components and cladding pressure coefficients and internal pressure coefficients for enclosed buildings.

Background: Components and cladding (C&C) coeffi-cients result in higher wind loads relative to main wind force resisting system (MWFRS) coefficients. When determin-ing C&C pressure coefficients (GCp), the effective wind area equals the tributary area of the framing member. For long and narrow tributary areas, the area width may be increased to one-third the framing member span to account for actual load distributions. This results in lower aver-age wind pressures. The increase in width applies only to calculation of wind force coefficients.

Example:Given -150 mph, Exposure B, 33' MRH, 10' wall height, 16" o.c. connection spacing.

pmax = qGCp - qGCpi

where: pmax = pressure on the wall

q = 21.15 psf (See Table C1.1)

GCp = external pressure coefficients for C&C

GCpi = +/- 0.18 internal pressure coefficient for enclosed buildings

Stud tributary area equals 13.3 ft2. The minimum required area for analysis is h2/3=33.3 ft2. The GCp equation is determined using ASCE 7-10 Figure 30.4-1.

End Zones (See Zone 5 as shown in WFCM Table 2.4): GCp = -1.4 for A ≤ 10 ft2

GCp = -0.8 - 0.6[(log(A/500)) / (log (10/500))] for 10 < A ≤ 500 ft2

GCp = -0.8 for A > 500 ft2

therefore:

GCp = -0.8 - 0.6[(log(33.3/500)) / (log (10/500))]

GCp = -1.22

The internal pressure coefficient (GCpi) is taken from ASCE 7-10 Table 26.11-1. GCpi = +/- 0.18

therefore:

pmax = 21.15 (-1.22 - 0.18)

= -29.61 psf (Negative pressure denotes suction)

The pressure is multiplied by half the stud height to obtain the unit lateral framing connection load:

= -29.61(10/2)

= |-148 plf| (WFCM Table 2.1)

Required capacity of lateral framing connections spaced at 16" o.c. is:

= 148plf (16 in./12 in./ft)

= 197 lbs = 148 (1.33) (WFCM Table 2.1 Footnote 3)

Footnote 1:Lateral framing connection loads are based on End Zone Coefficients (Zone 5) per the figure of Table 2.4. Where Interior Zones (Zone 4) occur, connection loads may be reduced. Adjustment of tabulated loads are conservatively based on a 20' wall height where A = 133 ft2.

End Zone

GCp = -0.8 - 0.6[(log(A/500)) / (log (10/500))]

= -0.8 - 0.6[(log(133/500)) / (log(10/500))]

= -1.00

Interior Zone

GCp = -0.8 - 0.3[(log(A/500)) / (log(10/500))]

= -0.8 - 0.3[(log(133/500)) / (log(10/500))]

= -0.9

The ratio of Zone 4 to Zone 5 loads is:

(-0.9-0.18) / (-1.0-0.18) = 0.92 (WFCM Table 2.1 Footnote 1)

Therefore, Interior Zone loads may be reduced to 92% of tabulated values.

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Table 2.2A Uplift Connection Loads from Wind (For Roof-to-Wall, Wall-to-Wall, and Wall-to-Foundation)

110 115 120 130 140 150 160 170 180 195

Roof Span (ft)

12 118 128 140 164 190 219 249 281 315 36924 195 213 232 272 315 362 412 465 521 61236 272 298 324 380 441 506 576 650 729 85648 350 383 417 489 567 651 741 836 938 110060 428 468 509 598 693 796 906 1022 1146 134512 70 80 92 116 142 171 201 233 267 32124 111 129 148 188 231 278 328 381 437 52836 152 178 204 260 321 386 456 530 609 73648 194 227 261 333 411 495 585 680 782 94460 236 276 317 406 501 604 714 830 954 115312 46 56 68 92 118 147 177 209 243 29724 69 87 106 146 189 236 286 339 395 48636 92 118 144 200 261 326 396 470 549 67648 116 149 183 255 333 417 507 602 704 86660 140 180 221 310 405 508 618 734 858 105712 22 32 44 68 94 123 153 185 219 27324 27 45 64 104 147 194 244 297 353 44436 32 58 84 140 201 266 336 410 489 61648 38 71 105 177 255 339 429 524 626 78860 44 84 125 214 309 412 522 638 762 96112 ‐ 8 20 44 70 99 129 161 195 24924 ‐ 3 22 62 105 152 202 255 311 40236 ‐ ‐ 24 80 141 206 276 350 429 55648 ‐ ‐ 27 99 177 261 351 446 548 71060 ‐ ‐ 29 118 213 316 426 542 666 865

1

2

3

12 16 19.2 24 48

1.00 1.33 1.60 2.00 4.004

5

6

7

8

25 psf

Multiplier

Connection Spacing (in.)

700‐yr. Wind Speed 3‐second gust (mph)

Tabulated uplift loads assume a building located in Exposure B with a mean roof height of 33 feet.  For buildings located in other exposures, the tabulated values for 0 psf roof dead load shall be multiplied by the appropriate adjustment factor in Section 2.1.3.1 then reduced by the appropriate design dead load.

15 psf

0 psf 8

Unit Connection Loads (plf)1,2,3,4,5,6,7Roof/Ceiling Assembly Design Dead Load

10 psf

20 psf

Tabulated uplift loads for 0 psf design dead load are included for interpolation or use with actual roof dead loads.

Tabulated unit uplift connection loads shall be permitted to be multiplied by 0.75 for framing not located within 6 feet of corners for buildings less than 30 feet in width (W), or W/5 for buildings greater than 30 feet in width.

Tabulated uplift loads are specified in pounds per linear foot of wall.  To determine connection requirements, multiply the tabulated unit uplift load by the multiplier from the table below corresponding to the spacing of the connectors:

Tabulated uplift loads are specified for roof‐to‐wall connections.  When calculating uplift loads for wall‐to‐wall or wall‐to‐foundation connections, tabulated uplift values shall be permitted to be reduced by 73 plf (0.60 x 121 plf) for each full wall above.

For jack rafter uplift connections, use a roof span equal to twice the jack rafter length. The jack rafter length includes the overhang length and the jack span.

When calculating uplift loads for ends of headers/girders, multiply the tabulated unit uplift load by 1/2 of the header/girder span (ft.).  Cripple studs need only be attached per typical uplift requirements.

Tabulated uplift loads equal total uplift minus 0.6 of the roof/ceiling assembly design dead load.

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Table 2.2A Uplift Connection Loads from Wind

Description: Uplift loads at the roof to wall connection. Procedure: Use Main Wind Force Resisting System

(MWFRS) coefficients to calculate wind uplift forces. Sum moments to compute maximum uplift force at the roof to wall connection.

Background: Per ASCE 7-10, worst case uplift loads occur at a 20 degree roof slope with wind perpendicular to the ridge and roof over-hang uplift forces included. Roof/ceiling gravity loads are included to resist uplift forces.

Example:Given - 150 mph, Exposure B, 33' MRH, 20 degree roof slope, 36' roof span, 2' overhangs, 15 psf roof/ceiling dead load, 16" o.c. connection spacing.

External pressure coefficients are taken from ASCE 7-10 Figure 28.4-1. Internal pressure coefficients are taken from ASCE 7-10 Table 26.11-1 and applied to the Windward Roof (WR) and Leeward Roof (LR). The pressure coef-ficient for the bottom surface of the Windward Overhang (WO) is computed using a gust factor (0.85) and a pressure coefficient (0.7) from sections ASCE 7-10 sections 26.9.1 and 28.4.3, respectively. The positive internal pressure co-efficient was applied to the bottom surface of the Leeward Overhang (LO) to model background pressure.

proof = pressure on the roof portion

proof = q(GCpf - GCpi), for each portion of the roofwhere:

q = 21.15 psf (See Table C1.1)

GCpf = external pressure coefficients for MWFRS

GCpi = +/- 0.18 internal pressure coefficient for enclosed buildings

End Zone:WO GCpf = -1.07, GCp = (0.85) (-0.7) = -0.60

WR GCpf = -1.07, GCpi = -0.18

LO GCpf = -0.69, GCpi = -0.18

LR GCpf = -0.69, GCpi = -0.18

Substituting:

pWO = 21.15 (-1.07 - 0.60) = -35.2 psf

pWR = 21.15 (-1.07 - 0.18) = -26.4 psf

pLR = 21.15 (-0.69 - 0.18) = -18.4 psf

pLO = 21.15 (-0.69 - 0.18) = -18.4 psf

Since dead loads in this case are resisting uplift forces, they are multiplied by 0.6, per ASCE 7-10 section 2.4.1. Thus roof/ceiling dead loads are equal to: (15 psf) 0.6 = 9 psf

Summing moments about the leeward roof-to-wall inter-section, the uplift forces are calculated for a 1' wide section through the building. To parallel the notation above, the forces retain the WR, WO, etc., notation and are preceded by a V (for vertical) or H (for horizontal):

VWO = -35.2(2) = -70.4 lbs

VWR = -26.4(36 / 2) = -475.2 lbs

VLR = -18.4(36 / 2) = -331.2 lbs

VLO = -18.4(2) = -36.8 lbs

HWO = -35.2(2)(tan(20°)) = -25.7 lbs

HWR = -26.4(36 / 2)(tan(20°)) = -173.0 lbs

HLR = -18.4(36 / 2)(tan(20°)) = -120.5 lbs

HLO = -18.4(2)(tan(20°)) = -13.4 lbs

The dead load of the roof, R, is also added:

RWO = 9(2) = 18 lbs

RWR = 9(18) = 162 lbs

RLO = 9(2) = 18 lbs

RLR = 9(18) = 162 lbs

Summing moments about the leeward top of wall:

ΣML = 0 = [-70.4+18][1+36] + [-475.2+162][9+18] + [-331.2+162][9]- [-36.8+18][1] + [(-25.7) (0.364)] - [(-173.0)(3.276) ] + [(-120.5)(3.276)] - [(-13.4)(0.364)] - 36FW

Solving for FW:

FW = -326 plf

Unit uplift connection load is:

= 326 plf (WFCM Table 2.2A)

Required uplift capacity of connections spaced at 16" o.c.

= 326 plf (16 in./12in./ft)

= 434 lbs = 326(1.33) (WFCM Table 2.2A Footnote 3)

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Footnote 1:Tabulated loads are based on end zone pressures. Where the requirements of footnote 1 are met, tabulated loads may be decreased as follows:

Given - 110 mph, Exposure B, 33' MRH, 20 degree roof slope, 12' roof span, 2' overhangs, 0 psf roof/ceiling dead load, 12" o.c.

End Zone uplift force is:

118 plf

Interior Zone uplift force based on calculation similar to exterior zone is:

88 plf

Reduction factor: = (88 plf) / (118 plf)

= 0.75

Dead Load

Leeward Wall

Wind Uplift Force

Uplift Force Reaction (FW)

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Table 2.9A Exterior Wall Stud Bending Stresses from Wind Loads (Cont.)

2x4 2x6 2x8 2x4 2x6 2x8 2x4 2x6 2x8 2x4 2x6 2x8 2x4 2x6 2x8

Wall Height

Stud Spacing

12 in. 903 366 211 1028 416 240 1160 470 270 1301 527 303 1527 618 35616 in. 1205 488 281 1371 555 319 1547 627 361 1735 702 404 2036 824 47424 in. 1807 732 421 2056 833 479 2321 940 541 2602 1054 606 3054 1237 71212 in. 1365 553 318 1553 629 362 1754 710 409 1966 796 458 2307 934 53816 in. 1820 737 424 2071 839 483 2338 947 545 2621 1062 611 3077 1246 71724 in. 2731 1106 636 3107 1258 724 3507 1420 817 3932 1592 916 4615 1869 107612 in. 1906 772 444 2168 878 505 2448 991 570 2744 1111 640 3220 1304 75116 in. 2541 1029 592 2891 1171 674 3263 1322 761 3659 1482 853 4294 1739 100124 in. 3811 1543 888 4336 1756 1011 4895 1982 1141 5488 2222 1279 ‐ 2608 150112 in. 2519 1020 587 2866 1161 668 3236 1310 754 3628 1469 845 4258 1724 99216 in. 3359 1360 783 3822 1548 891 4314 1747 1006 4837 1959 1127 5677 2299 132324 in. 5039 2040 1174 5733 2322 1336 ‐ 2621 1508 ‐ 2938 1691 ‐ 3448 198512 in. 3203 1297 746 3644 1476 849 4113 1666 959 4612 1868 1075 5412 2192 126116 in. 4270 1729 995 4858 1967 1132 5485 2221 1278 ‐ 2490 1433 ‐ 2922 168224 in. ‐ 2594 1493 ‐ 2951 1698 ‐ 3332 1917 ‐ 3735 2150 ‐ 4383 252312 in. 3952 1600 921 4496 1821 1048 5076 2056 1183 5691 2304 1326 ‐ 2705 155616 in. 5269 2134 1228 5995 2428 1397 ‐ 2741 1577 ‐ 3073 1768 ‐ 3606 207524 in. ‐ 3201 1842 ‐ 3642 2096 ‐ 4111 2366 ‐ 4609 2652 ‐ 5409 311312 in. 4764 1929 1110 5420 2195 1263 ‐ 2478 1426 ‐ 2778 1599 ‐ 3260 187616 in. ‐ 2572 1480 ‐ 2927 1684 ‐ 3304 1901 ‐ 3704 2132 ‐ 4347 250224 in. ‐ 3859 2221 ‐ 4390 2527 ‐ 4956 2852 ‐ 5556 3198 ‐ ‐ 3753

1

2

3

Induced fb (psi)1,2,3

195180150 160 170

8 ft

700‐yr. Wind Speed 

3‐second gust (mph)

Stud Size

10 ft

The tabulated bending stress (fb) shall be less than or equal to the allowable bending design value (Fb').

18 ft

20 ft

12 ft

14 ft

16 ft

Tabulated bending stresses assume a building located in Exposure B with a mean roof height of 33 feet.  For buildings located in other exposures, the tabulated values shall be multiplied by the appropriate adjustment factor in Section 2.1.3.1.Tabulated bending stresses shall be permitted to be multiplied by 0.92 for framing not located within 3 feet of corners for buildings less than 30 feet in width (W), or within W/10 of corners for buildings greater than 30 feet in width.

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Table 2.9A Exterior Wall Stud Bending Stresses from Wind Loads

Description: Bending stress in wall studs due to wind load.

Procedure: Compute wind pressures using C&C coef-ficients and calculate stud requirements.

Background: As in Table 2.4, peak suction forces are very high. Defining the effective wind area and the tributary area of the wall stud is key to computing the design suction. Stud span equals the wall height minus the thickness of the top and bottom plates. For a nominal 8' wall, the height is: 97 1/8" - 4.5" = 92 3/8". Two cases have been checked in these tables. For C&C wind pressures, the bending stresses are computed independent of axial stresses. In addition, the case in which bending stresses from MWFRS pressures act in combination with axial stresses from wind and gravity loads must be analyzed. For buildings limited to the conditions in this Manual, the C&C loads control the stud design.

Example: Given - 150 mph, Exposure B, 33' MRH, 10' wall height, 2x4 studs, 16" o.c. stud spacing.

Calculations from Table 2.10 for exterior wall induced moments from wind loads showed the applied bending moment for this case to be 464.6 ft-lbs.

Substituting this bending moment into a bending stress calculation:

fb = M(tabulated)/S

= 464.6 (12)/3.0625

= 1,820 psi

fb (Tabulated) = 1,820 psi (WFCM Table 2.9A)

Footnote 2:See Commentary Table 2.1 for calculation of footnotes.

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Table 2.10 Exterior Wall Induced Moments from Wind Loads

110 115 120 130 140 150 160 170 180 195

Wall HeightStud 

Spacing

12 in. 124 136 148 173 201 231 262 296 332 39016 in. 165 181 197 231 268 307 350 395 443 52024 in. 248 271 295 346 402 461 525 592 664 77912 in. 187 205 223 262 304 348 396 448 502 58916 in. 250 273 297 349 405 465 529 597 669 78524 in. 375 410 446 523 607 697 793 895 1004 117812 in. 262 286 311 365 424 486 553 625 700 82216 in. 349 381 415 487 565 648 738 833 934 109624 in. 523 572 622 731 847 973 1107 1249 1401 164412 in. 346 378 411 483 560 643 732 826 926 108716 in. 461 504 549 644 747 857 975 1101 1234 144924 in. 692 756 823 966 1120 1286 1463 1652 1852 217312 in. 440 480 523 614 712 817 930 1050 1177 138116 in. 586 641 697 819 949 1090 1240 1400 1569 184224 in. 879 961 1046 1228 1424 1635 1860 2100 2354 276312 in. 542 593 645 758 879 1009 1147 1295 1452 170416 in. 723 790 861 1010 1171 1345 1530 1727 1936 227324 in. 1085 1186 1291 1515 1757 2017 2295 2591 2905 340912 in. 654 715 778 913 1059 1216 1383 1562 1751 205516 in. 872 953 1038 1218 1412 1621 1844 2082 2334 274024 in. 1308 1429 1556 1826 2118 2432 2767 3123 3502 4110

1

2

16 ft

Induced Moment (ft‐lbs)1,2

14 ft

700‐yr. Wind Speed 3‐second gust (mph)

8 ft

10 ft

12 ft

Tabulated induced moments assume a building located in Exposure B with a mean roof height of 33 feet.  For buildings located in other exposures , the tabulated values shall be multiplied by the appropriate adjustment factor in Section 2.1.3.1. Tabulated induced moments shall be permitted to be multiplied by 0.92 for framing not located within 3 feet of corners for buildings less than 30 feet in width (W), or within W/10 of corners for buildings greater than 30 feet in width.

18 ft

20 ft

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Table 2.10 Exterior Wall Induced Moments From Wind Loads

Description: Applied moment on wall due to wind loads.

Procedure: Calculate the applied moment based on C&C wind pressures.

Background: Applied suction force is dependent on tributary areas.

Example:Given - 150 mph, Exposure B, 33' MRH, 10' wall height, 16" o.c. stud spacing.

pmax = 29.61 psf (See Commentary to Table 2.1)

w = pmax (16 in./12in./ft)

= 39.48 plf

Substituting this uniform load, w, into a bending calcula-tion for a simply supported member:

M wL=

=( ) −

= −

2

2

8

39 48 103 375

12

8

466

. (.

)

ft lbs

M(Tabulated) = 466 ft-lbs

(A value of 465ft-lbs is shown in WFCM Table 2.10 – dif-ference due to rounding in calculation of pmax)

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Table 2.11 Loadbearing Wall Loads from Snow or Live Loads (For Wall Studs, Headers, and Girders)

Dead Load Assumptions: Roof Assembly DL = 20 psf, Wall Assembly DL = 121 plf, Floor Assembly DL = 10 psf, Floor LL = 40 psf

RLL RLL RLL

20 30 50 70 20 30 50 70 20 30 50 70

320 360 493 627 200 260 367 473 240 259 351 443560 613 834 1056 320 405 568 732 480 517 702 887800 867 1178 1489 440 553 776 998 720 776 1053 13301280 1379 1872 2365 680 782 1089 1407 1200 1293 1755 2217

RLL RLL RLL RLL RLL

20 30 50 70 20 30 50 70 20 30 50 70 20 30 50 70 20 30 50 70

641 671 771 871 521 551 651 778 300* 300* 300* 300* 416 461 541 624 571 585 654 7241091 1130 1297 1463 851 890 1057 1237 600* 600* 600* 600* 641 705 827 950 1021 1049 1188 13261541 1591 1824 2058 1181 1231 1464 1700 900* 900* 900* 900* 866 951 1118 1284 1471 1513 1721 19292441 2515 2885 3255 1841 1915 2285 2655 1500* 1500* 1500* 1500* 1316 1392 1623 1862 2371 2441 2787 3134

RLL RLL RLL RLL RLL

20 30 50 70 20 30 50 70 20 30 50 70 20 30 50 70 20 30 50 70

1002* 1032 1132 1232 762 792 892 992 721* 721* 721* 721* 657 702 782 862 962* 962* 1015 10851722* 1731 1898 2064 1212 1251 1418 1584 1321* 1321* 1321* 1321* 1002 1066 1188 1311 1682* 1682* 1789 19272442* 2442* 2665 2899 1662 1712 1945 2179 1921* 1921* 1921* 1921* 1362 1432 1599 1765 2402* 2402* 2562 27703882* 3882* 4206 4576 2562 2636 3006 3376 3121* 3121* 3121* 3121* 2082 2113 2344 2583 3842* 3842* 4108 4455

1

*

GSL

3660

Unit Header/Girder Beam Loads (plf)1Roof Span (ft)

1224

Tabulated unit header/girder beam loads (plf) are based on the maximum load combination: Dead Load + Floor Live Load (i.e. D + L). Reduced unitloads are permitted for load combinations that include Roof Live Load (RLL) and Ground Snow Load (GSL).

GSL

Roof Span (ft) Unit Header/Girder Beam Loads (plf)1

Ground SnowLoad or RoofLive Load (psf)

GSL GSL GSL

2436

Unit Header/Girder Beam Loads (plf)1

Tabulated loads assume simply supported single span floor joists. For continuous two span floor joists, loads on interior loadbearing walls,headers, and girders shall be multiplied by 1.25.

Roof Span (ft)

1224

GSL

36

12

GSL GSL GSL GSLGround SnowLoad or RoofLive Load (psf)

60

60

GSL GSLGround Snow Loador Roof Live Load (psf)

GSL

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Table 2.11 Loadbearing Wall Loads From Snow or Live Loads (For Wall Studs, Headers, and Girders)

Description: Gravity loads on walls, headers, and gird-

Procedure: Sum gravity loads and calculate wall and

Background: In calculating the unit header/girder beam

Table 2.11, the following ASCE 7-10 load combinations were considered. When designing structural wood members, it is also necessary to consider the effect of

D

#1 1.25#2 1.00#3 1.15#4 1.25#5 1.15

2.11 were controlled by the Dead Load + Floor Live Load

Example:Given - Loadbearing wall supporting Roof, Ceiling, & 2

studs, 12" o.c., 20 psf roof dead load, 30 psf ground snow

Dead Load

Ridge

Left Side of Building

Floor Dead and Live Loads

Floor Dead and Live Loads

Header

Exterior Wall

Unbalanced Snow Load

LOAD COMBINATIONS:Per ASCE 7-10, the following load combinations were

1. Dead + Floor Live2. Dead + Snow3.

LOADS:

wroof dead = 20 psf [(36 ft/2) + 2ft] = 400 plf

wwalldead = 11 psf (11 ft)(2 walls) = 242 plf

wfloordead = 10 psf (36 ft/2) (2 floors) = 360 plf

TOTAL = 1,002 plf

qsnow = 0.7CeCtIpg

= 0.7(1.0)(1.1)(1.0)(30 psf)

= 23.1 psf

Rright(Snow) = 23.1 psf (36ft + 2ft + 2ft)/2

= 462 plf

qsnow = Ipg (building width < 40 ft)

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in Table 2.11), a more complex unbalanced snow load-ASCE 7-10 which places 30 percent

of the balanced snow load on the windward side of the roof and 100 percent of the balanced snow load plus a rectangular surcharge snow load on the leeward side of

dS(1/2) where hd is the roof step drift height and S is the slope expressed as the roof

to hd S(1/2) where is the unit weight of snow, which is a

function of the ground snow load, pg

The slope, S, assumed in calculating the unit header loads

Sum moments about the top of the wall opposite the unbal-anced roof snow load.

Mleft = 0

Mleft = [(30.0 psf)(28)][(36 ft/2) + 2] - 36RRight

Rright(Snow) = 467 plf Unbalanced Case Governs

In accordance with ASCE 7-10, balanced and unbalanced -

lation. Unbalanced snow loads are 1.3 (30.0/23.1) times larger than balanced snow loads, but only act along one

the exterior, unbalanced snow loads result in the maximum force to the wall.

wlive = 40 psf (36 ft/2)(2 floors) = 1,440 plf

wdead = 1,002 plf

wfloorlive = 1,440 plf

wsnow = 467 plf

Dead + Floor Live = 1,002 + 1,440

= 2,442 plf

Dead + Snow = 1,002 + 467

= 1,469 plf

= 1,002 + 0.75(1,440) + 0.75(467)

= 2,432 plf

wtotal = 2,442 plf (WFCM Table 2.11)

Tabulated values in Table 2.11 denoted with a “*” are in-

by the Dead Load plus Floor Live Load combination. The designer should therefore apply the appropriate load dura-tion factor, CD, of 1.0 when using these loads to design a wood header.

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Polling Question

4) Which of the following is true for calculating exterior wall stud stresses per WFCM?

a) Compute bending due to C&C wind loads independent of axial

b) Analyze bending due to MWFRS loads combined with axial from gravity and wind

c) C&C loads control stud design for buildings limited to WFCM conditions

d) All of the above

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PRESCRIPTIVE DESIGN

3.1 General Provisions 115

3.2 Connections 116

3.3 Floor Systems 119

3.4 Wall Systems 121

3.5 Roof Systems 123

List of Figures 125

List of Tables 146

Appendix A 303

WOOD FRAME CONSTRUCTION MANUAL

3

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3.1 General Provisions

3.1.1 Prescriptive Requirements

The provisions in Chapter 3 establish a specific set of resistance requirements for buildings meeting the scope of this document (see 1.1). Tabular wind requirements are provided for buildings sited in exposure categories B and C.

3.1.2 Equivalent Materials and Systems

The provisions of this Chapter are not intended to preclude the use of other methods or materials of con-struction. When alternative methods or materials are used, design loads and capacities shall be determined from the provisions of Chapter 2.

3.1.3 Prescriptive Design Limitations

Wood frame buildings built in accordance with Chap-ter 3 of this document shall be limited to the conditions of this section (see Table 3). Conditions not complying with Chapter 3 of this document shall be designed in ac-cordance with accepted engineering practice in accordance with Chapter 2.

3.1.3.1 Wind Exposure and Mean Roof HeightTabulated wind requirements in Chapter 3 are provided

for exposure categories B and C at a mean roof height of up to 33 feet. The building shall neither exceed three stories nor a mean roof height of 33 feet, measured from average grade to average roof elevation (see Figure 3.1a). Habitable attics shall be considered an additional floor for purposes of determining gravity and seismic loads.

3.1.3.2 Floor Systemsa. Framing Member Spans Single spans of floor

framing members shall not exceed 26 feet for lumber joists.b. Framing Member Spacings Floor framing member

spacings shall not exceed 24 inches on center for lumber joists, I-joists, and floor trusses.

c. Cantilevers Lumber floor joist cantilevers support-ing loadbearing walls shall not exceed the depth, d, of the joists (see Figure 2.1a). Lumber floor joist cantilevers supporting non-loadbearing walls shall be limited to L/4 (see Figure 2.1b). Lumber joists shall be located directly over studs when used in cantilever conditions.

EXCEPTION: For roof live loads and ground snow loads less than or equal to 20 psf and 30 psf, respectively, lumber floor joist cantilevers supporting load-bearing walls shall not exceed one-eighth of the backspan when supporting only a roof load where the roof clear span does not exceed 28 feet.

d. Setbacks Setbacks of loadbearing walls on lumber floor joist systems shall not exceed the depth, d, of the joists (see Figure 2.1d). Lumber floor joists shall be lo-cated directly over studs when used in setback conditions supporting loadbearing walls.

e. Vertical Floor Offsets Vertical floor offsets shall be limited to the floor depth, df, (including floor fram-ing members and floor sheathing), and the floor framing members on each side of the offset shall be lapped or tied together to provide a direct tension tie across the offset, and to transfer diaphragm shear in both orthogonal direc-tions (see Figure 2.1i).

f. Diaphragm Aspect Ratio Floor diaphragm lengths shall be in accordance with Tables 3.16B and 3.16C.

g. Diaphragm Openings Floor diaphragm openings shall not exceed the lesser of 12 feet or 50% of the build-ing dimension (see Figure 2.1k).

3.1.3.3 Wall Systemsa. Wall Heights Loadbearing walls shall not exceed

10 feet in height. Non-loadbearing walls shall not exceed 20 feet in height.

b. Wall Stud Spacings Wall stud spacings shall not exceed 24 inches on center.

c. Shear Wall Line Offsets Offsets in a shear wall line within a story shall not exceed 4 feet (see Figure 2.1l).

EXCEPTION: Where shear wall line offsets ex-ceed these limits, the structure shall be designed as separate structures attached in the plane of the offset. Shear wall length for the shared wall shall be the sum of the lengths required for the shared wall of each attached structure. For the purpose of determining wind loads, the structure shall be per-mitted to be considered as a rectangular structure with perimeter dimensions which inscribe the total structure (see Figure 3.1b). Distribution of shear loads into shear wall lines shall be proportional to the diaphragm area tributary to each shear wall line or by other accepted engineering practice.

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8d common nails spaced at a maximum of 6 inches on cen-ter at panel edges and 12 inches on center in the panel field.

3.2.5.4 Roof Cladding Roof cladding shall be attached in accordance with

the manufacturer’s recommendations.

3.2.5.5 Wall Cladding Wall cladding shall be attached in accordance with the

minimum nailing requirements in Table 3.11 or comply with the manufacturer’s recommendations.

3.2.6 Special Connections

3.2.6.1 Ridge Connection RequirementsRidge connections shall be in accordance with the

requirements given in Table 3.6. Prescriptive solutions for ridge straps are provided in Table A-3.6. Where ridge straps are used, they shall attach to opposing rafters.

EXCEPTION: Ridge straps are not required when collar ties (collar beams) of nominal 1x6 or 2x4 lumber are located in the upper third of the attic space and attached to rafters in accordance with Table A-3.6.

3.2.6.2 Jack RaftersJack rafters shall be attached to the wall assembly in

accordance with 3.2.2.1 and attached to hip beams in ac-cordance with Table 3.6.

3.2.6.3 Non-Loadbearing Wall Assemblies Rake overhang to wall, wall to wall, and wall to

foundation connections shall be in accordance with the requirements given in Table 3.4C (see Figures 2.1g-h). Walls which do not support the roof assembly and are at-tached in accordance with 3.2.1 need no additional uplift connections.

3.2.6.4 Connections around Wall Openings 3.2.6.4.1 Header and/or Girder to Stud Connections

Header and/or girder to stud connections shall be in accor-dance with the requirements given in Table 3.7. Window sill plate to stud connections shall be in accordance with the requirements given in Table 3.8.

3.2.6.4.2 Top and Bottom Plate to Full Height Studs When the number of full height studs required at each end of a header are selected from Table 3.23C, each stud shall be connected in accordance with the requirements given in Table 3.5. Prescriptive solutions for top and bottom plate to stud connections are provided in Table 3.5A.

EXCEPTION: When the number of full height studs required at each end of a header are selected from Table 3.23D, the capacity of the connection of the top or bottom plate to each full height stud shall be equal to the unit lateral load, w (plf), given in Table 3.5 times half of the header span, L/2 (ft), divided by the required number of full height studs, NFH, selected from Table 3.23D.

Top or Bottom Plate to Each Full Height Stud Connection = w * (L/2) / NFH

3.3 Floor Systems

3.3.1 Wood Joist Systems

3.3.1.1 Floor Joists Floor joists shall be in accordance with the maximum

spans for common species and grades of lumber floor joists specified in Tables 3.18A-B.

3.3.1.1.1 Notching and Boring Notches in the top or bottom edge of solid-sawn joists shall not be located in the middle one-third of the joist span. Notches in the outer thirds of the span shall not exceed one-sixth of the actual joist depth, and shall not be longer than one-third of the depth of the member. Where notches are made at the supports, they shall not exceed one-fourth the actual joist depth. Bored holes are limited in diameter to one-third the actual joist depth and the edge of the hole shall not be closer than 2 inches to the top or bottom edge of the joist. Bored holes shall not be located closer than 2 inches to a notch (see Figure 3.3a).

3.3.1.2 Bearing Joists shall bear directly on beams, girders, ledgers, or

loadbearing walls or be supported by hangers. Joist bear-ing shall not be less than 1-1/2 inches on wood or metal or 3 inches on masonry (see Figures 3.4a-e). Beams and girders shall bear on loadbearing walls, piles, concrete or masonry foundations, or beam hangers (see Figure 3.4f).

3.3.1.3 End Restraint Restraint against twisting shall be provided at the end

of each joist by fastening to a rim, band joist, header, or other member or by using full-height blocking between floor joist ends. Fasteners for end restraint shall be pro-vided in accordance with Table 3.1 (see Figures 3.4a-e).

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3.3.4 Floor Sheathing

3.3.4.1 Sheathing Spans Floor sheathing spans shall not exceed the provisions

of Table 3.14.

3.3.4.2 Sheathing Edge Support Edges of floor sheathing shall have approved

tongue-and-groove joints or shall be supported with block-ing, unless ¼ inch minimum thickness underlayment or 1½ inches of approved cellular or lightweight concrete is installed, or unless the finish floor is of ¾ inch wood strip.

3.3.5 Floor Diaphragm Bracing

For 700-year return period, 3-second gust wind speeds greater than 130 mph, blocking and connections shall be provided at panel edges perpendicular to floor framing members in the first two bays of framing and shall be spaced at a maximum of 4 feet on center. Nailing require-ments are given in Table 3.1 (see Figure 3.7b).

3.4 Wall Systems3.4.1 Exterior Walls

3.4.1.1 Wood Studs Wall studs shall be in accordance with the maximum

spans for common species and grades of walls studs specified in Tables 3.20A-B and spaced in accordance with Table 3.20C. Exterior loadbearing studs shall be limited to a height of 10 feet or less between horizontal supports as specified in Table 3.20C. Exterior non-loadbearing studs shall be limited to a height of 14 feet or less for 2x4 studs and 20 feet or less for 2x6 and 2x8 studs in accordance with Table 3.20C.

3.4.1.1.1 Notching and Boring Notches in either edge of studs shall not be located in the middle one-third of the stud length. Notches in the outer thirds of the stud length shall not exceed 25% of the actual stud depth. Bored holes shall not exceed 40% of the actual stud depth and the edge of the hole shall not be closer than 5/8 inch to the edge of the stud (see Figure 3.3b). Notches and holes shall not occur in the same cross-section.

EXCEPTION: Bored holes shall not exceed 60% of the actual stud depth when studs are doubled.

3.4.1.1.2 Stud Continuity Studs shall be continuous between horizontal supports, including but not limited to: girders, floor diaphragm assemblies, ceiling diaphragm assemblies, and roof diaphragm assemblies. When attic floor diaphragm or ceiling diaphragm assemblies are used to brace gable endwalls, the sheathing and fasteners shall be as specified in Table 3.15. The framing and connections shall be capable of transferring the loads into the ceiling or attic floor diaphragm (see Figures 3.7a-b).

3.4.1.1.3 Corners A minimum of three studs shall be provided at each corner of an exterior wall (see Figures 3.8a-b).

EXCEPTION: Reduced stud requirements shall be permitted provided shear walls are not con-tinuous to corners. Framing must be capable of transferring axial tension and compression loads from above and providing adequate backing for the attachment of sheathing and cladding materi-als.

3.4.1.2 Top Plates Double top plates shall be provided at the top of all

exterior stud walls. The double plates shall overlap at corners and at intersections with other exterior or interior loadbearing walls (see Figure 3.8d). Double top plates shall be lap spliced with end joints offset in accordance with the minimum requirements given in Table 3.21.

3.4.1.3 Bottom Plates Bottom plates shall not be less than 2 inch nominal

thickness and not less than the width of the wall studs. Studs shall have full bearing on the bottom plate.

3.4.1.4 Wall Openings Headers shall be provided over all exterior wall open-

ings. Headers shall be supported by wall studs, jack studs, hangers, or framing anchors (see Figures 3.9a-b).

3.4.1.4.1 Headers Maximum spans for common species of lumber headers and structural glued laminated timber beams used in exterior loadbearing walls shall not exceed the lesser of the applicable spans given in Tables 3.22A-E and Table 3.23A. Maximum spans for common species of lumber headers used in exterior non-loadbearing walls shall not exceed spans given in Table 3.23B.

3.4.1.4.2 Full Height Studs Full height studs shall meet the same requirements as exterior wall studs selected in 3.4.1.1 (see Figures 3.9a-b). The minimum number of full height studs at each end of the header shall not be less

Copyright © American Wood Council. Downloaded/printed pursuant to License Agreement. No reproduction or transfer authorized.40

AMERICAN WOOD COUNCIL

PRESCRIPTIVE DESIGN

than half the number of studs replaced by the opening, in accordance with Table 3.23C.

EXCEPTION: The minimum number of full height studs at each end of the header shall be permitted to be reduced in accordance with Table 3.23D. The capacity of the connection of the top or bottom plate to each full height stud shall be equal to the unit lateral load, w (plf) given in Table 3.5 times half of the header span, L/2 (ft.), divided by the required number of full height studs, NFH, selected from Table 3.23D.

Top or Bottom Plate to Each Full Height Stud Connection = w * (L/2) / NFH

3.4.1.4.3 Jack Studs Jack studs shall be at least Stud grade lumber. The minimum number of jack studs support-ing each end of a header shall not be less than jack stud requirements given in Table 3.22F (see Figures 3.9a-b). Full height studs selected in accordance with 3.4.1.4.2 shall be permitted to replace an equivalent number of jack studs, when adequate gravity connections are provided.

3.4.1.4.4 Window Sill Plates Maximum spans for window sill plates used in exterior walls shall not exceed the spans given in Table 3.23B.

3.4.2 Interior Loadbearing Partitions

3.4.2.1 Wood Studs Interior loadbearing studs shall be at least Stud grade

lumber.

EXCEPTION: Interior loadbearing studs sup-porting only a roof shall be at least Utility grade lumber.

3.4.2.1.1 Notching and Boring Notches in either edge of studs shall not be located in the middle one-third of the stud length. Notches in the outer thirds of the stud length shall not exceed 25% of the actual stud depth. Bored holes in interior loadbearing studs shall not exceed 40% of the actual stud depth and shall not be closer than 5/8 inch to the edge. Notches and holes shall not occur in the same cross-section (see Figure 3.3b).

EXCEPTION: Bored holes shall not exceed 60% of the actual stud depth when studs are doubled.

3.4.2.1.2 Stud Continuity Studs shall be continuous between horizontal supports, including but not limited to: girders, floor diaphragm assemblies, ceiling diaphragm

assemblies, and roof diaphragm assemblies.

3.4.2.2 Top Plates Double top plates shall be provided at the top of all

interior loadbearing partition walls. The double plates shall overlap at corners and at intersections with other exterior or interior loadbearing walls (see Figure 3.8d).

3.4.2.3 Bottom Plates Bottom plates shall not be less than 2 inch nominal

thickness and not less than the width of the wall studs. Studs shall have full bearing on the bottom plate.

3.4.2.4 Wall Openings Headers shall be provided over all interior loadbearing

wall openings. Headers shall be supported by wall studs, jack studs, joist hangers, or framing anchors.

3.4.2.4.1 Headers Maximum spans for common spe-cies of lumber headers and glued laminated beams are given in Tables 3.24A-B.

3.4.2.4.2 Studs Supporting Header Beams Jack studs shall be at least Stud grade lumber. The minimum number of jack studs supporting each end of a header shall not be less than jack stud requirements given in Table 3.24C (see Figures 3.9a-b). An equivalent number of full height studs shall be permitted to replace jack studs, when adequate gravity connections are provided.

3.4.3 Interior Non-Loadbearing Partitions

3.4.3.1 Wood Studs Interior non-loadbearing studs shall be at least Utility

grade lumber.3.4.3.1.1 Notching and Boring Notches in studs shall

not exceed 40% of the stud depth. Bored holes shall not exceed 60% of the stud depth and shall not be closer than 5/8 inch to the edge. Notches and holes shall not occur in the same cross-section.

3.4.3.2 Top Plates Single or double top plates shall be provided at the

top of all stud walls.

3.4.3.3 Bottom Plates Bottom plates shall not be less than 2 inch nominal

thickness and not less than the width of the wall studs. Studs shall have full bearing on the bottom plate.

Copyright © American Wood Council. Downloaded/printed pursuant to License Agreement. No reproduction or transfer authorized.41

PRESCRIPTIVE DESIGN

AMERICAN WOOD COUNCIL

C3.4.1.2 Top Plates Capacity of top plate splices is typi-cally controlled by diaphragm chord forces per Table 3.21. If large shear forces from the upper stories of a structure are transferred through the top plates to shear walls at the bottom story, drag strut forces, as opposed to chord forces, may govern the top plate slice design and should be considered.

C3.4.1.4 Wall OpeningsC3.4.1.4.1 Headers Maximum header spans are tabulated for both “raised” headers − headers are assumed to be laterally supported at ends and along their length, and

“dropped” headers − headers are assumed to be laterally supported at ends only. Dropped headers address the case where the header is not attached directly to the double-top plate framing as shown in Figure C3.4.1.4.1.

C3.4.4.2 Exterior Shear Walls Minimum length of full height sheathing on exterior shear walls is provided for wind design in Table 3.17A and for seismic design in Table 3.17C. Minimum lengths are calculated for Table 3.17A by assuming a top plate-to-ridge height of 10 feet and adjustments for other top plate-to-ridge heights are provided in footnote 4.

Figure C3.4.1.4.1 Dropped and Raised Headers

C3.5 Roof SystemsWood I-joists and wood trusses are not covered directly in the prescriptive provisions of Chapter 3 since product properties and installation recommendations are manu-facturer specific.

Raised Header

Full Height Stud

Double TopPlate

Window Sill Plate

Bottom Plate

Jack Stud

Dropped Header

Copyright © American Wood Council. Downloaded/printed pursuant to License Agreement. No reproduction or transfer authorized.42

November 2007 1 / 5

Dropped Header Design Guide

Consideration of the stability of deep beams is important to ensure proper product application. Typically, designers assume that perpendicularly framed roof or floor systems provide bracing to prevent beam buckling. However, in many parts of the country, framing practices call for "dropping" a header below the roof or floor framing and then building a short wall between the header and top plate. Figure 1 shows a typical example of this practice – a garage door header. If beam buckling is not considered in the design of a “dropped” header, a performance problem can occur. Review of “dropped” header applications has been conducted under uniform load, single span conditions. Based on this evaluation, the following recommendations have been developed for engineered lumber products. In addition, provisions in this guide are based on downward uniform vertical loads only and do not account for additional effects due to lateral loads; such as, wind or seismic. The building designer is responsible for accounting for any design effects due to lateral loads. Fully-Braced Dropped Header Applications Under some “dropped” conditions, a header may be assumed to be "fully-braced" and a design reduction does not need to be applied to account for buckling. These conditions are illustrated in Figure 2. For example, light duty headers (usually ≤ 12 in. deep), such as those over windows and sliding glass doors, may be considered fully-braced when the height of the wall above is 4 ft.-0 in. or less. The designer may also assume that deeper sections are fully-braced if designed within the constraints outlined in Figure 2. Other Dropped Header Applications Dropped headers with multiple spans, non-uniform loading, or with dimensions not addressed by Figure 2 may also be specified by the designer. However, beam stability must be considered in their design. A design example has been provided to illustrate a beam stability calculation in accordance with the 2005 National Design Specification for Wood Construction. A designer also has the option of detailing the header in a manner that provides the required lateral support to prevent beam buckling. Figure 3 illustrates a single span condition where lateral support has been provided by raising the primary structural header to the level of the perpendicular framing.

Figure 1: 2 ply 1 ¾ in. x 16 in. Buckled Garage Door Header

1" Lateral Deflection

43

WORKBOOKDesign of Wood Frame Buildings for High Wind, Snow, and Seismic Loads

WFCMWood Frame Construction Manual for One- and Two-Family Dwellings2015 EDITION

44

BUILDING DESCRIPTION

Figure 1: Isometric view (roof overhangs not shown).

45

AMERICAN WOOD COUNCIL

2015 Wood Frame Construction Manual Workbook 3

BUILDING DESCRIPTION

North

Wall Heights = 9' Windows Finished Grade to Foundation Top = 1' Typical 3'x4'-6" Floor Assembly Height = 1' Foyer 6'x4'-6" Roof Pitch = 7:12 Kitchen 4'x4'-6" House Mean Roof Height = 24.7' Bath 4'x6' Roof Overhangs = 2' Doors Building Length (L) = 40' Typical 3'x7'-6" Building Width (W) = 32' Foyer 6'x7'-6" Top plate to ridge height = 9.3' Kitchen 9'x7'-6"

AMERICAN WOOD COUNCIL

4 General Information

LOADS ON THE BUILDING

Structural systems in the WFCM 2015Edition have been sized using dead, live, snow, seismic and wind loads in accordance with ASCE/SEI 7-10 Minimum Design Loads for Buildings and Other Structures. Lateral Loads:

Wind:

3-second gust wind speed in Exposure Category B (700 yr. return) = 160 mph

Seismic:

Simplified Procedure (ASCE 7-10 Section 12.14)

Seismic Design Category (SDC) – (ASCE 7-10 Section 11.4.2 and IRC Subcategory) = D1

Vertical force distribution factor (F) - (ASCE 7-10 Section 12.14.8.1) = 1.2

Gravity Loads*:

Roof: Roof Dead Load = 10 psf Ground Snow Load, Pg = 30 psf Roof Live Load = 20 psf Ceiling: Roof Ceiling Load = 10 psf *Assumptions vary for wind and seismic dead loads Deflection limits per 2015 IRC Roof Rafters with flexible Ceiling Attached L/Δ = 240 Roof Rafters with no Ceiling Attached L/Δ = 180 Raised Ceiling Joists with flexible finish L/Δ = 240 Floor Joists L/Δ = 360 Exterior Studs (gypsum interior) H/Δ = 180

Note: See comparable deflection limits in 2015 IBC section 2308 for joists and rafters.

Floors: First Floor Live Load = 40 psf Second Floor Live Load = 30 psf Attic Floor Live Load = 30 psf Floor Dead Load = 10 psf

Walls: Wall Dead Load = 11 psf

2015 International Residential Code for One- and Two-Family Dwellings, International Code Council, Inc., Washington, DC. Reproduced with permission. All rights reserved. www.iccsafe.org

AMERICAN WOOD COUNCIL

56 First Story Design

Wall Sheathing Sheathing and Cladding (WFCM 3.4.4.1) Choose Exterior Wall Sheathing OR Cladding from Tables 3.13A and 3.13B respectively Three second gust wind speed (700 yr) and Exposure category: ................ 160 mph Exp. B Sheathing Type (wood structural panels, fiberboard, board, hardboard): ... WSP Strength Axis to Support (Parallel or Perpendicular): ................................ Parallel Stud Spacing: .............................................................................................. 16 in. Minimum Panel Thickness to resist suction loads: ..................................... 15/32 in.

LFH = 25 ft 1-2 North Elevation LFH = 22 ft

1-1 South Elevation

LFH = 25 ft 1-B East Elevation

LFH = 29 ft

1-A West Elevation

Wall Framing (cont’d) Exterior Loadbearing Wall Headers (WFCM 3.4.1.4.1)

Family Room Door Choose Headers in Loadbearing Walls from Tables 3.22A-E and Table 3.22F Building Width: .......................................................................................... 32 ft Required Span: ............................................................................................ 9 ft Ground Snow Load: .................................................................................... 30 psf Three second gust wind speed (700 yr.) and Exposure category: ............... 160 mph Exp. B Headers supporting roof, ceiling, and two center bearing floors Table 3.22D1 (Dropped) Preliminary Header Selection (Gravity Loads): ............................ 20F Glulam 3-1/8x13-3/4 Maximum Header/Girder Span (interpolated): ........................................... 9'-4" Table 3.22D2 (Raised) Preliminary Header Selection (Gravity Loads): ............................. 20F Glulam 3-1/8x13-3/4 Maximum Header/Girder Span (interpolated): ........................................... 9'-9" Table 3.22F Tabulated Number of Jack Studs Required (R+C+2CBF): ........................ 5 Roof Span Adjustment (Footnote 1: (W+12)/48): ...................................... 0.92 Adjusted no. of jack studs required = tabulated x roof span adjustment: ... 5 Table 3.23A (Dropped) Dropped Header Wind Load Check: ............................................. 20F Glulam 3-1/8x13-3/4 Maximum Header/Girder Span ................................................................... 11'-6" OK Table 3.23C Tabulated Number of Full Height (King) Studs: ........................................ 4* Reduced Full Height Stud Requirements (Table 3.23D) x/h = 0.15: .......... 3 Final Selection of Header Grade and Size: Gravity Loads Control: ............................................................ 20F Glulam 3-1/8x13-3/4 Number of Jack Studs Required (gravity controlled): ........................ 5** Number of Full Height (King) Studs Required (wind controlled): .... 3* (same species / grade as Loadbearing Studs (WFCM 3.4.1.4.2)) Using identical procedures: Foyer header (6' required): .................. 20F Glulam 3-1/8x9-5/8 6'-9" >6' OK Number of Jack Studs Required: ................................................... 3** Number of Full Height (King) Studs Required:............................. 2* Typical Window headers (3' required): ............... Dropped 2-2x8's 3'-8" >3' OK Typical Window headers (3' required): ................... Raised 2-2x6's 3'-0" >3' OK Number of Jack Studs Required: ................................................... 2** Number of Full Height (King) Studs Required:............................. 1

* Full height studs could be determined based on 24" o.c. spacing from Tables W6.1-W6.2. ** WFCM 3.4.1.4.3 allows jack studs to be replaced with an equivalent number of full height (king) studs if adequate gravity connections are provided.

If all first floor headers align vertically with second floor headers, only one floor is being carried and headers could be designed for more efficiency (Table 3.24A1/A2 adjusted by 1.4 for half the tributary area). However, jack studs still need to be designed for roof, ceiling, and two floors.

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PRESCRIPTIVE DESIGN

Table 3.22D1 Laterally Unsupported (Dropped) Header Spans for Exterior Loadbearing Walls

(Supporting a Roof, Ceiling, and Two Center Bearing Floors) Dead Load Assumptions:

Roof/Ceiling Assembly = 20 psf, Floor Assembly = 10psf, Wall Assembly = 121plf, L/DLL=360

DroppedExterior

12 24 36 12 24 36 12 24 36 12 24 36

Size

1-2x6 2 - 8 2 - 1 1 - 10 2 - 8 2 - 1 1 - 10 2 - 6 2 - 0 1 - 9 2 - 5 1 - 11 1 - 71-2x8 3 - 4 2 - 8 2 - 3 3 - 4 2 - 8 2 - 3 3 - 2 2 - 6 2 - 2 3 - 0 2 - 5 2 - 1

1-2x10 3 - 11 3 - 2 2 - 8 3 - 11 3 - 2 2 - 8 3 - 9 3 - 0 2 - 7 3 - 6 2 - 10 2 - 51-2x12 4 - 6 3 - 8 3 - 2 4 - 6 3 - 8 3 - 2 4 - 3 3 - 5 3 - 0 4 - 1 3 - 3 2 - 10

2-2x4 2 - 8 2 - 1 1 - 9 2 - 8 2 - 1 1 - 9 2 - 6 2 - 0 1 - 8 2 - 5 1 - 11 1 - 72-2x6 3 - 11 3 - 1 2 - 8 3 - 11 3 - 1 2 - 8 3 - 8 3 - 0 2 - 6 3 - 6 2 - 10 2 - 52-2x8 4 - 10 3 - 11 3 - 4 4 - 10 3 - 11 3 - 4 4 - 7 3 - 8 3 - 2 4 - 4 3 - 6 3 - 0

2-2x10 5 - 7 4 - 6 3 - 11 5 - 6 4 - 6 3 - 11 5 - 2 4 - 3 3 - 8 5 - 0 4 - 1 3 - 62-2x12 6 - 2 5 - 1 4 - 6 6 - 0 5 - 1 4 - 5 5 - 9 4 - 10 4 - 3 5 - 6 4 - 7 4 - 0

3-2x8 5 - 11 4 - 9 4 - 1 5 - 10 4 - 9 4 - 1 5 - 7 4 - 6 3 - 11 5 - 4 4 - 4 3 - 83-2x10 6 - 8 5 - 6 4 - 9 6 - 6 5 - 5 4 - 9 6 - 2 5 - 2 4 - 6 5 - 11 4 - 11 4 - 33-2x12 7 - 2 6 - 0 5 - 4 7 - 0 5 - 11 5 - 3 6 - 8 5 - 8 5 - 0 6 - 5 5 - 5 4 - 10

4-2x8 6 - 8 5 - 5 4 - 9 6 - 7 5 - 5 4 - 9 6 - 3 5 - 2 4 - 5 6 - 0 4 - 11 4 - 34-2x10 7 - 5 6 - 2 5 - 5 7 - 3 6 - 1 5 - 4 6 - 11 5 - 9 5 - 1 6 - 8 5 - 6 4 - 104-2x12 7 - 11 6 - 8 6 - 0 7 - 9 6 - 7 5 - 10 7 - 5 6 - 3 5 - 7 7 - 2 6 - 0 5 - 4

Size3.125x5.500 5 - 5 4 - 4 3 - 8 5 - 5 4 - 4 3 - 8 5 - 2 4 - 1 3 - 6 4 - 11 3 - 11 3 - 43.125x6.875 6 - 9 5 - 5 4 - 7 6 - 9 5 - 5 4 - 7 6 - 5 5 - 2 4 - 5 6 - 1 4 - 10 4 - 23.125x8.250 8 - 1 6 - 5 5 - 6 8 - 1 6 - 5 5 - 6 7 - 8 6 - 2 5 - 3 7 - 4 5 - 10 5 - 03.125x9.625 9 - 5 7 - 6 6 - 5 9 - 5 7 - 6 6 - 5 8 - 11 7 - 1 6 - 1 8 - 6 6 - 9 5 - 9

3.125x11.000 10 - 8 8 - 6 7 - 3 10 - 8 8 - 6 7 - 3 10 - 1 8 - 1 6 - 11 9 - 7 7 - 8 6 - 63.125x12.375 11 - 9 9 - 5 8 - 1 11 - 8 9 - 5 8 - 1 11 - 1 8 - 11 7 - 8 10 - 7 8 - 6 7 - 33.125x13.750 12 - 9 10 - 4 8 - 11 12 - 6 10 - 3 8 - 11 11 - 11 9 - 9 8 - 5 11 - 5 9 - 3 8 - 03.125x15.125 13 - 6 11 - 1 9 - 7 13 - 2 11 - 0 9 - 7 12 - 7 10 - 5 9 - 1 12 - 1 9 - 11 8 - 73.125x16.500 14 - 0 11 - 9 10 - 3 13 - 8 11 - 6 10 - 1 13 - 1 10 - 11 9 - 7 12 - 7 10 - 5 9 - 23.125x17.875 14 - 5 12 - 2 10 - 9 14 - 2 11 - 11 10 - 7 13 - 6 11 - 4 10 - 0 13 - 0 10 - 10 9 - 73.125x19.250 14 - 10 12 - 6 11 - 1 14 - 7 12 - 3 10 - 11 13 - 11 11 - 9 10 - 5 13 - 5 11 - 3 10 - 03.125x20.625 15 - 2 12 - 9 11 - 5 14 - 11 12 - 7 11 - 3 14 - 3 12 - 0 10 - 9 13 - 9 11 - 7 10 - 43.125x22.000 15 - 6 13 - 1 11 - 8 15 - 3 12 - 11 11 - 7 14 - 7 12 - 4 11 - 0 14 - 0 11 - 10 10 - 73.125x23.375 15 - 9 13 - 4 12 - 0 15 - 6 13 - 2 11 - 10 14 - 10 12 - 7 11 - 4 14 - 4 12 - 2 10 - 103.125x24.750 16 - 1 13 - 7 12 - 3 15 - 10 13 - 5 12 - 1 15 - 2 12 - 11 11 - 7 14 - 7 12 - 5 11 - 1

5.125x5.500 7 - 0 5 - 6 4 - 9 7 - 0 5 - 6 4 - 9 6 - 8 5 - 3 4 - 6 6 - 4 5 - 0 4 - 35.125x6.875 8 - 9 6 - 11 5 - 11 8 - 9 6 - 11 5 - 11 8 - 4 6 - 7 5 - 8 7 - 10 6 - 3 5 - 45.125x8.250 10 - 6 8 - 3 7 - 1 10 - 6 8 - 3 7 - 1 9 - 11 7 - 11 6 - 9 9 - 5 7 - 6 6 - 55.125x9.625 12 - 2 9 - 8 8 - 3 12 - 2 9 - 8 8 - 3 11 - 7 9 - 2 7 - 10 11 - 0 8 - 8 7 - 5

5.125x11.000 13 - 11 11 - 0 9 - 5 13 - 11 11 - 0 9 - 5 13 - 2 10 - 6 9 - 0 12 - 6 9 - 11 8 - 65.125x12.375 15 - 7 12 - 4 10 - 7 15 - 7 12 - 4 10 - 7 14 - 9 11 - 9 10 - 1 14 - 0 11 - 2 9 - 65.125x13.750 17 - 3 13 - 8 11 - 8 17 - 3 13 - 8 11 - 8 16 - 4 13 - 0 11 - 2 15 - 6 12 - 4 10 - 75.125x15.125 18 - 10 15 - 0 12 - 10 18 - 10 15 - 0 12 - 10 17 - 10 14 - 3 12 - 3 16 - 11 13 - 6 11 - 75.125x16.500 20-0† 16 - 3 13 - 11 20-0† 16 - 3 13 - 11 19 - 3 15 - 5 13 - 3 18 - 4 14 - 8 12 - 75.125x17.875 20-0† 17 - 6 15 - 0 20-0† 17 - 6 15 - 0 20-0† 16 - 7 14 - 3 19 - 7 15 - 9 13 - 65.125x19.250 20-0† 18 - 8 16 - 1 20-0† 18 - 8 16 - 1 20-0† 17 - 8 15 - 3 20-0† 16 - 9 14 - 55.125x20.625 20-0† 19 - 9 17 - 1 20-0† 19 - 8 17 - 1 20-0† 18 - 8 16 - 2 20-0† 17 - 9 15 - 45.125x22.000 20-0† 20-0† 18 - 0 20-0† 20-0† 18 - 0 20-0† 19 - 6 17 - 0 20-0† 18 - 7 16 - 25.125x23.375 20-0† 20-0† 18 - 10 20-0† 20-0† 18 - 8 20-0† 20-0† 17 - 8 20-0† 19 - 4 16 - 105.125x24.750 20-0† 20-0† 19 - 7 20-0† 20-0† 19 - 4 20-0† 20-0† 18 - 4 20-0† 20 - 0 17 - 6

†1

23

50 psf 70 psf30 psf20 psf

The number of jack studs required at each end of the header shall be determined from Table 3.22F.

Roof Live Load Ground Snow Load

Tabulated spans are based on #2 Grade Hem-Fir, and are applicable to species with equal or greater Fb and E from the NDS Supplement (i.e., Douglas Fir-Larch, Southern Pine, or Spruce-Pine-Fir). For #3 Grade lumber, spans shall be multiplied by 0.75.Tabulated spans assume 20F combination glulam with a minimum Fbx=2,000psi, Fvx=210psi, and E=1,500,000psi.

Spans are limited to 20 feet in length.

Maximum Header/Girder Spans (ft-in.) for Common Lumber Species1,3,4

Roof, Ceiling, and Two Center

Bearing Floors

Headers Supporting

Maximum Header/Girder Spans (ft-in.) for Glued Laminated Timber Beams2,3,4

Building Width (ft)

† Spansarelimitedto20feetinlength.1 TabulatedspansarebasedonthelowestFb,Fv,andEfor#2GradeDouglasFir-Larch,Hem-Fir,SouthernPine,andSpruce-Pine-Fir.For#3Gradelumber,spansshallbemultipliedby0.75.2 Tabulatedspansassume20FcombinationglulamwithaminimumFbx=2,000psi,Fvx=210psi,andE=1,500,000psi.3 ThenumberofjackstudsrequiredateachendoftheheadershallbedeterminedfromTable3.22F.4 Spanscheckedforliveloaddeflectiononly.

Copyright © American Wood Council. Downloaded/printed pursuant to License Agreement. No reproduction or transfer authorized.50

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WOOD FRAME CONSTRUCTION MANUAL

Table 3.22D2 Laterally Supported (Raised) Header Spans for Exterior Loadbearing Walls

(Supporting a Roof, Ceiling, and Two Center Bearing Floors) Dead Load Assumptions:

Roof/Ceiling Assembly = 20 psf, Floor Assembly = 10psf, Wall Assembly = 121plf, L/DLL=360

12 24 36 12 24 36 12 24 36 12 24 36

Size

1-2x6 2 - 8 2 - 1 1 - 10 2 - 8 2 - 1 1 - 10 2 - 7 2 - 0 1 - 9 2 - 5 1 - 11 1 - 81-2x8 3 - 5 2 - 8 2 - 4 3 - 5 2 - 8 2 - 4 3 - 3 2 - 7 2 - 2 3 - 1 2 - 5 2 - 1

1-2x10 4 - 0 3 - 2 2 - 9 4 - 0 3 - 2 2 - 9 3 - 10 3 - 1 2 - 7 3 - 8 2 - 11 2 - 51-2x12 4 - 9 3 - 9 3 - 2 4 - 9 3 - 9 3 - 2 4 - 6 3 - 7 3 - 1 4 - 3 3 - 5 2 - 11

2-2x4 2 - 8 2 - 1 1 - 9 2 - 8 2 - 1 1 - 9 2 - 6 2 - 0 1 - 8 2 - 5 1 - 11 1 - 72-2x6 4 - 0 3 - 2 2 - 8 4 - 0 3 - 2 2 - 8 3 - 9 3 - 0 2 - 7 3 - 7 2 - 10 2 - 52-2x8 5 - 0 4 - 0 3 - 5 5 - 0 4 - 0 3 - 5 4 - 10 3 - 10 3 - 3 4 - 7 3 - 7 3 - 1

2-2x10 6 - 0 4 - 9 4 - 0 6 - 0 4 - 9 4 - 0 5 - 8 4 - 6 3 - 10 5 - 5 4 - 3 3 - 82-2x12 7 - 0 5 - 7 4 - 9 7 - 0 5 - 7 4 - 9 6 - 8 5 - 4 4 - 6 6 - 4 5 - 0 4 - 3

3-2x8 6 - 4 5 - 0 4 - 3 6 - 4 5 - 0 4 - 3 6 - 0 4 - 9 4 - 1 5 - 8 4 - 6 3 - 103-2x10 7 - 6 5 - 11 5 - 1 7 - 6 5 - 11 5 - 1 7 - 1 5 - 8 4 - 10 6 - 9 5 - 4 4 - 73-2x12 8 - 10 7 - 0 5 - 11 8 - 10 7 - 0 5 - 11 8 - 5 6 - 8 5 - 8 8 - 0 6 - 4 5 - 4

4-2x8 7 - 3 5 - 9 4 - 11 7 - 3 5 - 9 4 - 11 6 - 11 5 - 6 4 - 8 6 - 7 5 - 2 4 - 54-2x10 8 - 8 6 - 10 5 - 10 8 - 8 6 - 10 5 - 10 8 - 3 6 - 6 5 - 7 7 - 10 6 - 2 5 - 34-2x12 10 - 2 8 - 1 6 - 10 10 - 2 8 - 1 6 - 10 9 - 8 7 - 8 6 - 7 9 - 2 7 - 3 6 - 2

Size3.125x5.500 5 - 6 4 - 4 3 - 8 5 - 6 4 - 4 3 - 8 5 - 2 4 - 2 3 - 6 4 - 11 3 - 11 3 - 43.125x6.875 6 - 10 5 - 5 4 - 7 6 - 10 5 - 5 4 - 7 6 - 6 5 - 2 4 - 5 6 - 2 4 - 11 4 - 23.125x8.250 8 - 2 6 - 6 5 - 6 8 - 2 6 - 6 5 - 6 7 - 10 6 - 2 5 - 3 7 - 5 5 - 10 5 - 03.125x9.625 9 - 7 7 - 7 6 - 6 9 - 7 7 - 7 6 - 6 9 - 1 7 - 3 6 - 2 8 - 8 6 - 10 5 - 10

3.125x11.000 10 - 11 8 - 8 7 - 5 10 - 11 8 - 8 7 - 5 10 - 5 8 - 3 7 - 1 9 - 10 7 - 10 6 - 83.125x12.375 12 - 4 9 - 9 8 - 4 12 - 4 9 - 9 8 - 4 11 - 9 9 - 3 7 - 11 11 - 1 8 - 9 7 - 63.125x13.750 13 - 8 10 - 10 9 - 3 13 - 8 10 - 10 9 - 3 13 - 0 10 - 4 8 - 10 12 - 4 9 - 9 8 - 43.125x15.125 15 - 1 11 - 11 10 - 2 15 - 1 11 - 11 10 - 2 14 - 4 11 - 4 9 - 8 13 - 7 10 - 9 9 - 23.125x16.500 16 - 5 13 - 0 11 - 1 16 - 5 13 - 0 11 - 1 15 - 7 12 - 5 10 - 7 14 - 10 11 - 9 10 - 03.125x17.875 17 - 9 14 - 1 12 - 0 17 - 9 14 - 1 12 - 0 16 - 11 13 - 5 11 - 5 16 - 0 12 - 8 10 - 103.125x19.250 19 - 2 15 - 2 12 - 11 19 - 2 15 - 2 12 - 11 18 - 3 14 - 5 12 - 4 17 - 3 13 - 8 11 - 83.125x20.625 20-0† 16 - 3 13 - 10 20-0† 16 - 3 13 - 10 19 - 6 15 - 6 13 - 3 18 - 6 14 - 8 12 - 63.125x22.000 20-0† 17 - 4 14 - 9 20-0† 17 - 4 14 - 9 20-0† 16 - 6 14 - 1 19 - 8 15 - 7 13 - 43.125x23.375 20-0† 18 - 4 15 - 8 20-0† 18 - 4 15 - 8 20-0† 17 - 7 15 - 0 20-0† 16 - 7 14 - 23.125x24.750 20-0† 19 - 4 16 - 7 20-0† 19 - 4 16 - 7 20-0† 18 - 6 15 - 10 20-0† 17 - 6 15 - 0

5.125x5.500 7 - 0 5 - 6 4 - 9 7 - 0 5 - 6 4 - 9 6 - 8 5 - 3 4 - 6 6 - 4 5 - 0 4 - 35.125x6.875 8 - 9 6 - 11 5 - 11 8 - 9 6 - 11 5 - 11 8 - 4 6 - 7 5 - 8 7 - 11 6 - 3 5 - 45.125x8.250 10 - 6 8 - 4 7 - 1 10 - 6 8 - 4 7 - 1 10 - 0 7 - 11 6 - 9 9 - 6 7 - 6 6 - 55.125x9.625 12 - 3 9 - 8 8 - 3 12 - 3 9 - 8 8 - 3 11 - 8 9 - 3 7 - 11 11 - 1 8 - 9 7 - 6

5.125x11.000 14 - 0 11 - 1 9 - 5 14 - 0 11 - 1 9 - 5 13 - 4 10 - 7 9 - 0 12 - 8 10 - 0 8 - 65.125x12.375 15 - 9 12 - 6 10 - 8 15 - 9 12 - 6 10 - 8 15 - 0 11 - 11 10 - 2 14 - 3 11 - 3 9 - 75.125x13.750 17 - 6 13 - 10 11 - 10 17 - 6 13 - 10 11 - 10 16 - 8 13 - 3 11 - 3 15 - 10 12 - 6 10 - 85.125x15.125 19 - 2 15 - 3 13 - 0 19 - 2 15 - 3 13 - 0 18 - 3 14 - 6 12 - 5 17 - 4 13 - 9 11 - 95.125x16.500 20-0† 16 - 7 14 - 2 20-0† 16 - 7 14 - 2 19 - 9 15 - 10 13 - 6 18 - 9 15 - 0 12 - 105.125x17.875 20-0† 17 - 10 15 - 4 20-0† 17 - 10 15 - 4 20-0† 17 - 0 14 - 8 20-0† 16 - 2 13 - 105.125x19.250 20-0† 19 - 0 16 - 4 20-0† 19 - 0 16 - 4 20-0† 18 - 2 15 - 8 20-0† 17 - 3 14 - 105.125x20.625 20-0† 20-0† 17 - 5 20-0† 20-0† 17 - 5 20-0† 19 - 4 16 - 8 20-0† 18 - 5 15 - 95.125x22.000 20-0† 20-0† 18 - 6 20-0† 20-0† 18 - 6 20-0† 20-0† 17 - 8 20-0† 19 - 6 16 - 95.125x23.375 20-0† 20-0† 19 - 6 20-0† 20-0† 19 - 6 20-0† 20-0† 18 - 8 20-0† 20-0† 17 - 85.125x24.750 20-0† 20-0† 20-0† 20-0† 20-0† 20-0† 20-0† 20-0† 19 - 8 20-0† 20-0† 18 - 7

†1

23 The number of jack studs required at each end of the header shall be determined from Table 3.22F.

Roof Live Load Ground Snow Load30 psf

Spans are limited to 20 feet in length.

Maximum Header/Girder Spans (ft-in.) for Common Lumber Species1,3,4

Maximum Header/Girder Spans (ft-in.) for Glued Laminated Timber Beams2,3,4

Building Width (ft)

Tabulated spans assume 20F combination glulam with a minimum Fbx=2,000psi, Fvx=210psi, and E=1,500,000psi.

50 psf

Roof, Ceiling, and Two Center

Bearing Floors

Headers Supporting

20 psf

Tabulated spans are based on #2 Grade Hem-Fir, and are applicable to species with equal or greater Fb and E from the NDS Supplement (i.e., Douglas Fir-Larch, Southern Pine, or Spruce-Pine-Fir). For #3 Grade lumber, spans shall be multiplied by 0.75.

70 psf

RaisedExterior

† Spansarelimitedto20feetinlength.1 TabulatedspansarebasedonthelowestFb,Fv,andEfor#2GradeDouglasFir-Larch,Hem-Fir,SouthernPine,andSpruce-Pine-Fir.For#3Gradelumber,spansshallbemultipliedby0.75.2 Tabulatedspansassume20FcombinationglulamwithaminimumFbx=2,000psi,Fvx=210psi,andE=1,500,000psi.3 ThenumberofjackstudsrequiredateachendoftheheadershallbedeterminedfromTable3.22F.4 Spanscheckedforliveloaddeflectiononly.

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Table 3.22F Jack Stud Requirements for Headers in Exterior Loadbearing Walls

3"(2‐2x)

4.5"(3‐2x)

5" 6"(4‐2x)

3"(2‐2x)

4.5"(3‐2x)

5" 6"(4‐2x)

3"(2‐2x)

4.5"(3‐2x)

5" 6"(4‐2x)

3"(2‐2x)

4.5"(3‐2x)

5" 6"(4‐2x)

Header Span (ft)

2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 14 1 1 1 1 1 1 1 1 2 1 1 1 2 2 1 16 2 1 1 1 2 1 1 1 2 2 2 1 3 2 2 28 2 2 2 1 2 2 2 1 3 2 2 2 4 3 2 210 3 2 2 2 3 2 2 2 4 3 2 2 5 3 3 312 3 2 2 2 3 2 2 2 4 3 3 2 5 4 3 314 4 3 2 2 4 3 2 2 5 4 3 3 6 4 4 316 4 3 3 2 4 3 3 2 6 4 4 3 7 5 4 418 4 3 3 2 5 3 3 3 6 4 4 3 8 5 5 420 5 3 3 3 5 4 3 3 7 5 4 4 9 6 5 52 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 14 2 1 1 1 2 1 1 1 2 2 1 1 2 2 2 16 2 2 2 1 3 2 2 2 3 2 2 2 3 2 2 28 3 2 2 2 3 2 2 2 4 3 2 2 4 3 3 210 4 3 2 2 4 3 3 2 5 3 3 3 5 4 3 312 4 3 3 2 5 3 3 3 5 4 3 3 6 4 4 314 5 4 3 3 5 4 3 3 6 4 4 3 7 5 4 416 6 4 4 3 6 4 4 3 7 5 4 4 8 5 5 418 6 4 4 3 7 5 4 4 8 5 5 4 9 6 6 520 7 5 4 4 7 5 5 4 9 6 5 5 10 7 6 52 1 1 1 1 1 1 1 1 2 1 1 1 2 1 1 14 2 2 2 1 2 2 2 1 3 2 2 2 3 2 2 26 3 2 2 2 3 2 2 2 4 3 2 2 4 3 3 28 4 3 3 2 4 3 3 2 5 3 3 3 5 4 3 310 5 3 3 3 5 3 3 3 6 4 4 3 6 4 4 312 6 4 4 3 6 4 4 3 7 5 4 4 7 5 5 414 6 4 4 3 7 5 4 4 8 5 5 4 8 6 5 416 7 5 5 4 7 5 5 4 9 6 5 5 10 7 6 518 8 6 5 4 8 6 5 4 10 7 6 5 11 7 7 620 9 6 6 5 9 6 6 5 11 7 7 6 12 8 7 62 1 1 1 1 1 1 1 1 2 1 1 1 2 1 1 14 2 2 2 1 2 2 2 1 3 2 2 2 3 2 2 26 3 2 2 2 3 2 2 2 4 3 2 2 4 3 3 28 4 3 3 2 4 3 3 2 5 3 3 3 5 4 3 310 5 4 3 3 5 4 3 3 6 4 4 3 6 4 4 312 6 4 4 3 6 4 4 3 7 5 4 4 8 5 5 414 7 5 4 4 7 5 4 4 8 5 5 4 9 6 6 516 8 5 5 4 8 6 5 4 9 6 6 5 10 7 6 518 9 6 5 5 9 6 6 5 10 7 6 5 11 8 7 620 10 7 6 5 10 7 6 5 11 8 7 6 12 8 8 62 2 1 1 1 2 1 1 1 2 1 1 1 2 2 1 14 3 2 2 2 3 2 2 2 3 2 2 2 4 3 2 26 5 3 3 3 5 3 3 3 5 3 3 3 5 4 3 38 6 4 4 3 6 4 4 3 6 4 4 3 7 5 4 410 7 5 5 4 7 5 5 4 8 5 5 4 8 6 5 412 9 6 5 5 9 6 5 5 9 6 6 5 10 7 6 514 10 7 6 5 10 7 6 5 11 7 7 6 12 8 7 616 11 8 7 6 11 8 7 6 12 8 8 6 13 9 8 718 13 9 8 7 13 9 8 7 14 9 8 7 15 10 9 820 14 9 9 7 14 9 9 7 15 10 9 8 16 11 10 8

1

2

3

Where the number of jack studs equals 1, the header shall be permitted to be supported by a framing anchor attached to the full‐height wall stud.

An equivalent number of full height studs are permitted to replace jack studs, when adequate gravity connections are provided.

Header Width

Roof, Ceiling, and One Clear Span Floor

Roof, Ceiling, and Two 

Center Bearing Floors

Roof, Ceiling, and Two Clear Span Floors

Jack stud requirements are based on a roof span (W) of 36 feet.  For other roof spans, the tabulated number of jack studs required at each end of the header shall be multiplied by (W + 12)/48.

Header Supporting

Number of Jack Studs Required at Each End of the Header1,2,3

Roof and Ceiling

Roof, Ceiling, and One 

Center Bearing Floor

Roof Live Load Ground Snow Load20 psf 30 psf 50 psf 70 psf

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Table 3.23A Laterally Unsupported (Dropped) Header Spans for Exterior Loadbearing Walls Resisting Wind Loads Dropped

110 115 120 130 140 150 160 170 180 195

5 - 8 5 - 5 5 - 2 4 - 9 4 - 5 4 - 2 3 - 11 3 - 8 3 - 5 3 - 26 - 3 6 - 0 5 - 9 5 - 3 4 - 11 4 - 7 4 - 3 4 - 0 3 - 10 3 - 66 - 8 6 - 5 6 - 2 5 - 8 5 - 3 4 - 11 4 - 7 4 - 4 4 - 1 3 - 97 - 2 6 - 10 6 - 7 6 - 1 5 - 7 5 - 3 4 - 11 4 - 7 4 - 4 4 - 06 - 6 6 - 3 6 - 0 5 - 6 5 - 2 4 - 9 4 - 6 4 - 3 4 - 0 3 - 88 - 0 7 - 8 7 - 4 6 - 9 6 - 3 5 - 10 5 - 6 5 - 2 4 - 11 4 - 6

8 - 10 8 - 5 8 - 1 7 - 6 6 - 11 6 - 6 6 - 1 5 - 8 5 - 5 5 - 09 - 6 9 - 1 8 - 8 8 - 0 7 - 5 6 - 11 6 - 6 6 - 1 5 - 9 5 - 4

10 - 1 9 - 8 9 - 3 8 - 7 7 - 11 7 - 5 6 - 11 6 - 6 6 - 2 5 - 810 - 10 10 - 4 9 - 11 9 - 2 8 - 6 7 - 11 7 - 5 7 - 0 6 - 7 6 - 111 - 7 11 - 1 10 - 7 9 - 10 9 - 1 8 - 6 8 - 0 7 - 6 7 - 1 6 - 612 - 4 11 - 10 11 - 4 10 - 6 9 - 9 9 - 1 8 - 6 8 - 0 7 - 7 7 - 012 - 6 11 - 11 11 - 5 10 - 7 9 - 10 9 - 2 8 - 7 8 - 1 7 - 7 7 - 013 - 5 12 - 10 12 - 3 11 - 4 10 - 6 9 - 10 9 - 2 8 - 8 8 - 2 7 - 714 - 3 13 - 8 13 - 1 12 - 1 11 - 3 10 - 6 9 - 10 9 - 3 8 - 9 8 - 1

10 - 7 10 - 1 9 - 8 8 - 11 8 - 4 7 - 9 7 - 3 6 - 10 6 - 5 6 - 011 - 10 11 - 4 10 - 10 10 - 0 9 - 3 8 - 8 8 - 1 7 - 8 7 - 3 6 - 812 - 11 12 - 5 11 - 10 11 - 0 10 - 2 9 - 6 8 - 11 8 - 4 7 - 11 7 - 414 - 0 13 - 4 12 - 10 11 - 10 11 - 0 10 - 3 9 - 7 9 - 1 8 - 7 7 - 11

14 - 11 14 - 4 13 - 8 12 - 8 11 - 9 11 - 0 10 - 3 9 - 8 9 - 2 8 - 515 - 10 15 - 2 14 - 6 13 - 5 12 - 5 11 - 7 10 - 11 10 - 3 9 - 8 8 - 1116 - 8 16 - 0 15 - 4 14 - 2 13 - 2 12 - 3 11 - 6 10 - 10 10 - 3 9 - 517 - 6 16 - 9 16 - 1 14 - 10 13 - 9 12 - 10 12 - 1 11 - 4 10 - 9 9 - 1118 - 4 17 - 6 16 - 9 15 - 6 14 - 5 13 - 5 12 - 7 11 - 10 11 - 2 10 - 419 - 1 18 - 3 17 - 6 16 - 1 15 - 0 14 - 0 13 - 1 12 - 4 11 - 8 10 - 919 - 9 18 - 11 18 - 1 16 - 9 15 - 6 14 - 6 13 - 7 12 - 10 12 - 1 11 - 220-0† 19 - 7 18 - 9 17 - 4 16 - 1 15 - 0 14 - 1 13 - 3 12 - 6 11 - 720-0† 20-0† 19 - 4 17 - 11 16 - 7 15 - 6 14 - 6 13 - 8 12 - 11 11 - 1120-0† 20-0† 20 - 0 18 - 5 17 - 1 16 - 0 15 - 0 14 - 1 13 - 4 12 - 320-0† 20-0† 20-0† 19 - 0 17 - 7 16 - 5 15 - 5 14 - 6 13 - 8 12 - 8

16 - 11 16 - 2 15 - 6 14 - 3 13 - 3 12 - 5 11 - 7 10 - 11 10 - 4 9 - 618 - 10 18 - 1 17 - 4 16 - 0 14 - 10 13 - 10 13 - 0 12 - 3 11 - 6 10 - 820-0† 19 - 9 18 - 11 17 - 6 16 - 3 15 - 2 14 - 3 13 - 4 12 - 8 11 - 820-0† 20-0† 20-0† 18 - 11 17 - 6 16 - 4 15 - 4 14 - 5 13 - 8 12 - 720-0† 20-0† 20-0† 20-0† 18 - 9 17 - 6 16 - 5 15 - 5 14 - 7 13 - 620-0† 20-0† 20-0† 20-0† 19 - 11 18 - 7 17 - 5 16 - 5 15 - 6 14 - 320-0† 20-0† 20-0† 20-0† 20-0† 19 - 7 18 - 4 17 - 3 16 - 4 15 - 120-0† 20-0† 20-0† 20-0† 20-0† 20-0† 19 - 3 18 - 1 17 - 1 15 - 920-0† 20-0† 20-0† 20-0† 20-0† 20-0† 20-0† 18 - 11 17 - 10 16 - 620-0† 20-0† 20-0† 20-0† 20-0† 20-0† 20-0† 19 - 8 18 - 7 17 - 220-0† 20-0† 20-0† 20-0† 20-0† 20-0† 20-0† 20-0† 19 - 4 17 - 1020-0† 20-0† 20-0† 20-0† 20-0† 20-0† 20-0† 20-0† 20 - 0 18 - 520-0† 20-0† 20-0† 20-0† 20-0† 20-0† 20-0† 20-0† 20-0† 19 - 020-0† 20-0† 20-0† 20-0† 20-0† 20-0† 20-0† 20-0† 20-0† 19 - 820-0† 20-0† 20-0† 20-0† 20-0† 20-0† 20-0† 20-0† 20-0† 20-0†

†

1

2

3

4

5

5.125x5.500

Spans are limited to 20 feet in length.Tabulated spans shall be permitted to be divided by 0.96, for framing not located within 8 feet of building corners.The number of jack studs required at each end of the header shall be determined from Table 3.22F. Tabulated spans are based on the lowest Fb and E for #2 Grade Douglas Fir-Larch, Hem-Fir, Southern PIne, and Spruce-Pine-Fir. Tabulated spans assume 20F combination glulam with a minimum Fby = 800 psi.The number of full height studs required at each end of the header shall be determined in accordance with Table 3.23C.

5.125x9.6255.125x11.0005.125x12.3755.125x13.7505.125x15.1255.125x16.5005.125x17.8755.125x19.250

5.125x24.750

Maximum Header/Girder Spans (ft-in.) for Glued Laminated Timber Beams1,2,4,5

2-2x12

3.125x9.6253.125x11.000

3-2x83-2x103-2x124-2x8

Size

3.125x5.5003.125x6.8753.125x8.250

3.125x13.7503.125x15.1253.125x16.500

5.125x6.875

3.125x12.375

3.125x23.375

5.125x20.6255.125x22.0005.125x23.375

3.125x24.750

5.125x8.250

Size

2-2x41-2x12

3.125x20.6253.125x22.000

3.125x17.8753.125x19.250

Maximum Header/Girder Spans (ft-in.) for Common Lumber Species1,2,3,5

1-2x101-2x81-2x6

2-2x62-2x8

2-2x10

4-2x104-2x12

700-yr. Wind Speed 3-second gust (mph)

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Table 3.23C Full Height Stud Requirements for Headers or Window Sill Plates in Exterior Walls Resisting Wind Loads

ExposuresB & C

12 16 24

1 1 12 2 13 3 24 3 25 4 36 5 37 6 48 6 49 7 510 8 5

1

8101214

Wall Stud Spacing (in.)

Header Span (ft)Number of Full Height Stud Required at 

Each End of the Header1

246

20The number of full height studs required at each end of the header shall be permitted to be reduced in accordance with the requirements of Section 3.4.1.4.2 and Table 3.23D.

1618

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Table 3.23D Reduced Full Height Stud Requirements for Headers or Window Sill Plates in Exterior Walls Resisting Wind Loads

ExposuresB & C

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Wall Stud Spacing (in.)

1 1 1 1 1 1 1 1 1 1 11 1 2 2 2 2 2 2 2 1 11 2 2 3 3 3 3 3 2 2 11 2 3 4 4 4 4 4 3 2 11 2 4 5 5 5 5 5 4 2 11 3 4 6 6 6 6 6 4 3 11 3 5 6 7 7 7 6 5 3 11 3 6 7 8 8 8 7 6 3 11 4 6 8 9 9 9 8 6 4 11 4 7 9 10 10 10 9 7 4 11 1 1 1 1 1 1 1 1 1 11 1 1 2 2 2 2 2 1 1 11 1 2 2 3 3 3 2 2 1 11 2 2 3 3 3 3 3 2 2 11 2 3 4 4 4 4 4 3 2 11 2 3 4 5 5 5 4 3 2 11 2 4 5 6 6 6 5 4 2 11 3 4 6 6 6 6 6 4 3 11 3 5 6 7 7 7 6 5 3 11 3 5 7 8 8 8 7 5 3 11 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 11 1 1 2 2 2 2 2 1 1 11 1 2 2 2 2 2 2 2 1 11 1 2 3 3 3 3 3 2 1 11 2 2 3 3 3 3 3 2 2 11 2 3 3 4 4 4 3 3 2 11 2 3 4 4 4 4 4 3 2 11 2 3 4 5 5 5 4 3 2 11 2 4 5 5 5 5 5 4 2 1

1

24

Header Span (ft) Number of Full Height Stud Required at Each End of the Header1

18

12

16

18

Distance from Top Plate Down to Header (a) or Distance from Bottom Plate Up to Window Sill Plate (b) to Wall Height (x/h), where x is the larger of a or b

101214

2

14

20

The capacity of the connection of the top or bottom plate to each full height stud shall be equal to the unit lateral load (w) given on Table 3.5 times half of the header span (L/2) divided by the required number of full height studs (NFH) selected from 3.23D.Top or Bottom Plate to Each Full Height Stud Connection = w*(L/2)/NFH

20

246

16

12

12

246810

1618

8

46810

14

20

16

Double Top Plate

Header

Bottom Plate

Full HeightStud Jack Stud

WindowSill Plate

a

b

h

Double Top Pla t e

Hea de r

Bo� om Pl at e

Full Hei g htS t ud Jac k S t ud

W i ndowS il l Plat e

a

b

h

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Exterior Non-Loadbearing Wall Headers and Window Sill Plates (WFCM 3.4.1.4.1 and 3.4.1.4.4) Choose Window Sill Plates from Table 3.23B Three second gust wind speed (700 yr) and Exposure category: ................ 160 mph Exp. B Required Span: ............................................................................................ 3 and 4 ft Selection of Window Sill Plate Grade, and Size: ...................................... 1-2x6 (flat) Tabulated Window Sill Plate Span: ............................................................ 6'-11" Wall Height Adjustment (Footnote 3: (H/10)1/2): ....................................... 0.95 Adjusted Maximum Sill Plate Length: Tabulated maximum sill plate Length ÷ Wall Height Adjustment: ..... 7'-3" > 4' OK Table 3.23C Number of Full Height (King) Studs Required: .......................................... 2 Reduced Full Height Stud Requirements (Table 3.23D) x/h = 0.25: .......... 2 Interior Loadbearing Wall Headers (WFCM 3.4.2.4.1)

Living Room Door Choose Headers for Interior Loadbearing Walls from Tables 3.24A-C Building Width: .......................................................................................... 32 ft Required Span: ............................................................................................ 6 ft Header supporting two center bearing floors Table 3.24B1 (Dropped) Selection of Header Grade and Size: ............................................. 20F Glulam 3-1/8x9-5/8 Maximum Header/Girder Span (interpolated): ........................................... 6'-1" ft. > 6' OK Table 3.24B2 (Raised) Selection of Header Grade and Size: ............................................ 20F Glulam 3-1/8x9-5/8 Maximum Header/Girder Span (interpolated): ........................................... 6'-1" ft. > 6' OK Number of Jack Studs Required (Table 3.24C): ......................................... 4 Using identical procedures: Foyer header (4' required): ............................................................. 2-2x10 4'-0" > 4' OK Number of Jack Studs Required (Table 3.24C): ......................................... 3 Interior Non-Loadbearing Wall Headers (WFCM 3.4.1.4.1)

Ends of Hallway The 2015 International Residential Code (IRC) section R602.7.3 allows a single flat 2x4 for interior non-loadbearing walls up to 8' spans.

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110 115 120 130 140 150 160 170 180 195

(ft-in.) (ft-in.) (ft-in.) (ft-in.) (ft-in.) (ft-in.) (ft-in.) (ft-in.) (ft-in.) (ft-in.)

6 - 9 6 - 5 6 - 2 5 - 8 5 - 3 4 - 11 4 - 8 4 - 4 4 - 1 3 - 1010 - 1 9 - 8 9 - 3 8 - 6 7 - 11 7 - 5 6 - 11 6 - 6 6 - 2 5 - 810 - 0 9 - 7 9 - 2 8 - 5 7 - 10 7 - 4 6 - 10 6 - 5 6 - 1 5 - 815 - 0 14 - 4 13 - 8 12 - 8 11 - 9 11 - 0 10 - 3 9 - 8 9 - 2 8 - 5

1

2

3

4

Maximum Header/Girder Spans for Common Lumber Species1,2,3,4

700-yr. Wind Speed 3-second gust (mph)

Size

1-2x4 (flat)

Tabulated spans shall be permitted to be divided by 0.96, for framing not located within 8 feet of building corners.

Tabulated spans are based on 10 foot wall heights. For other wall heights, H, the tabulated spans shall be divided by (H/10)1/2.

Tabulated spans are based on the lowest Fb and E for #2 Grade Douglas Fir-Larch, Hem-Fir, Southern PIne, and Spruce-Pine-Fir.

The number of full height studs required at each end of the header shall be determined in accordance with Table 3.23C.

1-2x6 (flat)2-2x4 (flat)2-2x6 (flat)

110 115 120 130 140 150 160 170 180 195

(ft-in.) (ft-in.) (ft-in.) (ft-in.) (ft-in.) (ft-in.) (ft-in.) (ft-in.) (ft-in.) (ft-in.)

5 - 9 5 - 6 5 - 3 4 - 10 4 - 6 4 - 2 3 - 11 3 - 8 3 - 6 3 - 38 - 7 8 - 2 7 - 10 7 - 3 6 - 9 6 - 3 5 - 11 5 - 6 5 - 3 4 - 108 - 6 8 - 1 7 - 9 7 - 2 6 - 8 6 - 3 5 - 10 5 - 6 5 - 2 4 - 9

12 - 8 12 - 2 11 - 8 10 - 9 10 - 0 9 - 4 8 - 9 8 - 3 7 - 9 7 - 21

2

3

4

Tabulated spans are based on 10 foot wall heights. For other wall heights, H, the tabulated spans shall be divided by (H/10)1/2. Tabulated spans are based on the lowest Fb and E for #2 Grade Douglas Fir-Larch, Hem-Fir, Southern PIne, and Spruce-Pine-Fir. The number of full height studs required at each end of the header shall be determined in accordance with Table 3.23C.

1-2x6 (flat)2-2x4 (flat)

Tabulated spans shall be permitted to be divided by 0.96, for framing not located within 8 feet of building corners.2-2x6 (flat)

Maximum Header/Girder Spans for Common Lumber Species1,2,3,4

700-yr. Wind Speed 3-second gust (mph)

Size

1-2x4 (flat)

Table 3.23B Laterally Unsupported (Dropped) Header Spans for Exterior Non-Loadbearing Walls and Window Sill Plate Spans Resisting Wind Loads

Table 3.23B Laterally Unsupported (Dropped) Header Spans for Exterior Non-Loadbearing Walls and Window Sill Plate Spans Resisting Wind Loads

Exposure C

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Connections (cont’d) Special Connections (WFCM 3.2.6) Connections around Wall Openings (WFCM 3.2.6.4) Typical Window Choose Header/Girder Connections based on loads from Table 3.7 Three second gust wind speed (700 yr) and Exposure category: ................ 160 mph Exp. B Roof Span: .................................................................................................. 32 ft Header Span (Typical Window): ................................................................ 9 ft Required Connection Capacity at Each End of Header: Tabulated Uplift Capacity (interpolated): ................................................... 1636 lbs Floor load adjustment (per footnote 3: 36plf x header span): ..................... -324 lbs Adjusted Uplift Capacity ............................................................................ 1312 lbs Tabulated Lateral Capacity: ....................................................................... 756 lbs Top/bottom plate to FHS Connection (3.4.1.4.2 Exception) = w*(L/2)/NFH w = 155 plf (Table 3.5); Z' = 125 lbs (Table 3.5A Commentary) Required capacity = 232 lbs. Dividing by Z' yields: ...................... 2-16d Commons All shorter headers will require lower capacity. Using identical procedures: Window (6' header) Adjusted Uplift Capacity (interpolated): .................... 1091 lbs Window (6' header) Tabulated Lateral Capacity: ....................................... 504 lbs Window (4' header) Adjusted Uplift Capacity (interpolated): .................... 583 lbs Window (4' header) Tabulated Lateral Capacity: ....................................... 336 lbs Window (3' header) Adjusted Uplift Capacity (interpolated): .................... 437 lbs Window (3' header) Tabulated Lateral Capacity: ....................................... 252 lbs Choose Window Sill Plate Connections based on loads from Table 3.8 Three second gust wind speed (700 yr) and Exposure category: ................ 160 mph Exp. B Window Sill Plate Span: ............................................................................. 3 ft Tabulated Lateral Connection Capacity - Each End of Window Sill: ....... 252 lbs

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AMERICAN WOOD COUNCIL

Exposure B

PRESCRIPTIVE DESIGN

Table 3.7 Header Connection Requirements for Wind (Dead Load Assumptions: Roof Assembly DL = 15 psf)

U2,3,4 L U2,3,4 L U2,3,4 L U2,3,4 L U2,3,4 L U2,3,4 L U2,3,4 L U2,3,4 L U2,3,4 L U2,3,4 L

2 48 79 59 87 70 94 95 111 122 129 151 148 181 168 214 190 248 212 304 2494 95 159 118 173 141 189 190 222 244 257 301 295 362 336 428 379 497 425 608 4996 143 238 176 260 211 283 285 333 366 386 452 443 544 504 641 569 745 637 912 7488 191 317 235 347 282 378 381 443 487 514 602 590 725 672 855 758 994 850 1216 99810 238 397 294 434 352 472 476 554 609 643 753 738 906 839 1069 948 1242 1062 1520 124712 286 476 353 520 422 567 571 665 731 771 903 885 1087 1007 1283 1137 1491 1275 1824 149614 334 555 412 607 493 661 666 776 853 900 1054 1033 1268 1175 1497 1327 1739 1487 2128 174616 381 635 470 694 563 756 761 887 975 1028 1204 1181 1449 1343 1710 1516 1987 1700 2432 199518 429 714 529 781 634 850 856 998 1097 1157 1355 1328 1631 1511 1924 1706 2236 1912 2736 224420 477 794 588 867 704 944 951 1108 1218 1285 1505 1476 1812 1679 2138 1895 2484 2125 3041 24942 71 79 89 87 108 94 149 111 193 129 240 148 290 168 344 190 401 212 492 2494 141 159 178 173 216 189 297 222 385 257 479 295 580 336 688 379 801 425 984 4996 212 238 267 260 324 283 446 333 578 386 719 443 870 504 1031 569 1202 637 1476 7488 283 317 356 347 432 378 595 443 770 514 959 590 1161 672 1375 758 1603 850 1968 99810 353 397 445 434 540 472 744 554 963 643 1199 738 1451 839 1719 948 2003 1062 2460 124712 424 476 534 520 648 567 892 665 1156 771 1438 885 1741 1007 2063 1137 2404 1275 2953 149614 495 555 623 607 757 661 1041 776 1348 900 1678 1033 2031 1175 2406 1327 2805 1487 3445 174616 565 635 712 694 865 756 1190 887 1541 1028 1918 1181 2321 1343 2750 1516 3205 1700 3937 199518 636 714 801 781 973 850 1338 998 1733 1157 2158 1328 2611 1511 3094 1706 3606 1912 4429 224420 707 794 890 867 1081 944 1487 1108 1926 1285 2397 1476 2901 1679 3438 1895 4007 2125 4921 24942 94 79 120 87 146 94 203 111 264 129 330 148 400 168 475 190 555 212 682 2494 189 159 240 173 293 189 406 222 529 257 660 295 801 336 950 379 1109 425 1364 4996 283 238 360 260 439 283 609 333 793 386 990 443 1201 504 1426 569 1664 637 2046 7488 377 317 479 347 586 378 813 443 1058 514 1321 590 1602 672 1901 758 2218 850 2728 99810 472 397 599 434 732 472 1016 554 1322 643 1651 738 2002 839 2376 948 2773 1062 3411 124712 566 476 719 520 879 567 1219 665 1586 771 1981 885 2402 1007 2851 1137 3328 1275 4093 149614 660 555 839 607 1025 661 1422 776 1851 900 2311 1033 2803 1175 3327 1327 3882 1487 4775 174616 755 635 959 694 1172 756 1625 887 2115 1028 2641 1181 3203 1343 3802 1516 4437 1700 5457 199518 849 714 1079 781 1318 850 1828 998 2379 1157 2971 1328 3604 1511 4277 1706 4991 1912 6139 224420 943 794 1198 867 1465 944 2032 1108 2644 1285 3301 1476 4004 1679 4752 1895 5546 2125 6821 2494

U = Connector uplift load.L = Connector lateral load (perpendicular to the wall).

1

2

3

4

24

160 170

Required Capacity of Connection at Each End of Header (lbs)1

140120 180110 195150130700‐yr. Wind Speed3‐ second gust (mph)

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For jack rafter uplift connections, use a roof span equal to twice the jack rafter length. The jack rafter length includes the overhang length and the jack span.

Tabulated lateral connection requirements shall be permitted to be multiplied by 0.75 and 0.92, respectively, for framing not located within 8 feet of building corners.Tabulated connection requirements assume a roof assembly dead load of 9 psf  (0.6 x 15 psf = 9 psf).

Tabulated uplift loads are specified for headers supporting a roof assembly.  When calculating uplift loads for headers supporting floor loads, thetabulated uplift loads shall be permitted to be reduced by 36 plf times the header span for each full wall above.

36

Header Span (ft)

Roof Span(ft)

12

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Wall Detailing Summary (cont’d) Table W6.19 Header Detailing Requirements for Wind and Gravity Loads

Header Span and Details Ext. Loadbearing (1-1&1-2)

Ext. Non-loadbearing Headers & Sill Plates

(1-A&1-B) Int. Loadbearing

9'

Type Dropped or Raised - -

Size/Plies 20F Glulam 3-1/8x13-3/4 - -

Uplift load 1312 - - Lateral load 756 - - No. Jack studs 5 - - No. King studs 3 - - King to plate nails 2-16d comm. - -

6'

Type Dropped or Raised - Dropped or Raised

Size/Plies 20F Glulam 3-1/8x9-5/8 - 20F Glulam

3-1/8x9-5/8 Uplift load 1091 - n/a Lateral load 504 - n/a No. Jack studs 3 - 4 No. King studs 2 - 1 King to plate nails 2-16d comm. - n/a

4'

Type - Dropped Dropped or Raised Size/Plies - 1-2x6 flat 2-2x10 Uplift load - n/a n/a Lateral load - 336 n/a No. Jack studs - n/a 3 No. King studs - 2 1 King to plate nails - 2-16d comm. n/a

3'

Type Dropped or Raised Dropped - Size/Plies 2-2x8 1-2x6 flat - Uplift load 437 n/a - Lateral load 252 252 - No. Jack studs 2 n/a - No. King studs 1 2 - King to plate nails 2-16d comm. 2-16d comm. -

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Wall Detailing Summary (cont’d) Table W6.20 Header Detailing Requirements for Gravity Loads Only

Header Span and Details Ext. Loadbearing (1-1 & 1-2)

Ext. Non-loadbearing Headers & Sill Plates

(1-A & 1-B) Int. Loadbearing

9'

Type Dropped or Raised - -

Size/Plies 20F Glulam 3-1/8x13-3/4 - -

No. Jack studs 5 - - No. King studs 1 - -

6'

Type Dropped or Raised Dropped or Raised -

Size/Plies 20F Glulam 3-1/8x9-5/8 1-2x6 flat -

No. Jack studs 3 n/a - No. King studs 1 1 -

4'

Type - Dropped or Raised Dropped or Raised Size/Plies - 1-2x6 flat 2-2x10 No. Jack studs - n/a 3 No. King studs - 1 1

3'

Type Dropped or Raised Dropped or Raised - Size/Plies 2-2x8 1-2x6 flat - No. Jack studs 2 n/a - No. King studs 1 1 -

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Polling Question

5) Which of the following is false regarding dropped headers?

a) Requires a lateral wind load check

b) Assumes full lateral buckling restraint

c) Spans less than a comparable raised header

d) None of the above

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This concludes the American Institute of Architects Continuing Education Systems Course

info@awc.org

www.awc.org

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