Course: IRC Wall Bracing Requirements and Narrow Wall Bracing Options

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CourseIRC Wall Bracing Requirements and Narrow
Wall Bracing Options

• Texas Residential Construction Commision
• Course Number 2008-05-0222

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• Presented by
• Ed Underwood
• Engineered Wood Specialist

972/840-6479 ed.underwood_at_apawood.org
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QSD
TSD
FSD
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Wall Bracing for the International Residential
Code SDC A Wind less than 100 mph A TECHNICAL
SEMINAR FOR ENGINEERS, ARCHITECTS,BUILDING
DESIGNERS, CODE OFFICIALS, AND CONTRACTORS
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IntroductionWhy Bracing?
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IntroductionWhy Bracing?
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Hold down examples (versus) Anchor bolts
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APA The Engineered Wood Association

• Why Bracing?
• Narrow Bracing in the Code
• The APA Narrow Wall Bracing Method Solution

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Why Brace Walls?
Prevent Racking
1971 San Fernando
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Lateral Loads National Issue

• Earthquake Hazard

• Wind Hazard

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F-5 Tornado Path
1999 Moore, OK
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Fujita Damage Scale
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Percentage of Occurrence

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Safe Rooms
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Suggested ReferenceAvailable at www.fema.gov
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2003 Missouri
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2003 Missouri
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Tornado Report
www.apawood.org
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Vertical Load Path
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Lateral Load Path
Why Bracing Units?
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Wind Forces Acting on Area
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Prescriptive vs.Engineered Construction
Prescriptive Construction

• Buildings up to 3 stories
• Maximum wall height of 10
• For normal lateral loads
• Calculations are NOT needed
• Prescriptive bracing the norm

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Prescriptive vs.Engineered Construction
Prescriptive Construction

• Buildings up to 3 stories
• Maximum wall height of 10
• For normal lateral loads
• Calculations are NOT needed
• Prescriptive bracing the norm

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Prescriptive vs.Engineered Construction
Engineered Construction
Prescriptive Construction

• Any building size
• Wind speeds gt 110 mph
• Typically Seismic Zones D E
• Irregular, large geometries
• Calculations required
• Utilizes shear walls

• Buildings up to 3 stories
• Maximum wall height of 10
• For normal lateral loads
• Calculations are NOT needed
• Prescriptive bracing the norm

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Braced Wall Methods (IRC 602.10.3)
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Bracing Units (IBC 2308.9.3, IRC 602.10.3)

• Let-in bracing
• Diagonal lumber boards
• Wood structural panels
• Fiberboard sheathing
• Gypsum sheathing
• Particleboard
• Plaster
• Hardboard

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Bracing Unit Widths
8 foot
8 foot
4 foot
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Bracing BasicsDefinitions
BRACED WALL PANEL (BWP)
48" BWP
3.7
BRACED WALL LINE (BWL)
R202
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Table R602.10.1Wall Bracing
Note Discuss loads on 3-story walls.
Note Method 3 is wood structural panels (plywood
or OSB)
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Bracing Basics Braced Panel Construction Methods
Method 3 - Wood Structural Panel
48"
48"
48"
R602.10.3
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Bracing Basics Wall Panel Spacing
DOES THIS MEET CODE ?
NO, 25' MAXIMUM EXCEEDED
48"
48"
36'
R602.10.1, Table R602.10.1
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Bracing Basics Wall Panel Spacing
DOES THIS MEET CODE ?
YES, 25' MAXIMUM NOT EXCEEDED
20'
48"
48"
48"
36'
R602.10.1, Table R602.10.1
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Bracing Basics Wall Panel Spacing
MINIMUM REQUIREMENTS
48"
48"
R602.10.1, Table R602.10.1
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Bracing Basics Wall Panel Spacing
DOES THIS MEET CODE ?
NO
48"
48"
3.7
18'
R602.10.1, Table R602.10.1
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Bracing Basics Wall Panel Spacing
Does this meet code?
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No
R602.10.1, Table R602.10.1
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48 Bracing Units
1970 UBC
48"
48"
48"
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Minimum Bracing Unit Width
When using infill sheathing
48"
48"
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Minimum Bracing Unit Width
When using infill sheathing
48"
48"
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Bracing Unit Widths
Windows
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Alt. Braced Wall Panels (IRC 602.10.6)
48 or 96

32 2003 28 2006 IRC
3322222
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Narrow Solutions (IBC 2308.9.3.1, IRC 602.10.6)

• 28 Inch Bracing Units (2006 IRC)

With Hold Downs
With Hold Downs
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Bracing Basics Alternate Panel Construction
Methods
R602.10.6
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28 Bracing
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Braced Wall Methods (IRC 602.10.3)
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48 or 96
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2003/6 International Residential Code (Fully
Sheathed Method)
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High-Wind Event
Fully Sheathed
Foam Sheathed

2003 Missouri
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IRC 24" Fully Sheathed Method
IRC R602.10.5

• Submitted by NAHB Research Center
• Simple and builder friendly
• Not for every wall sheathing type

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IRC 24" Fully Sheathed Method
IRC R602.10.5

• For fully sheathed walls only

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IRC 24" Fully Sheathed Method
IRC R602.10.5

• For fully sheathed walls only

OSB/Plywood Wall Sheathing Shares
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IRC 24" Fully Sheathed Method
24"
24"
24"
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IRC 24" Fully Sheathed Method
24"
24"
24"
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Continuous Sheathing

• No hold-downs

24"
24"
24"
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Continuous Sheathing

• No hold-downs
• Full Sheathing
• Corner Detail

24"
24"
24"
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Corner Framing Detail (Typ.)
16d nail at 24" o.c.
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Fully Sheathed Homes
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IRC 24" Fully Sheathed Method
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Continuous WSP SheathingTable R602.10.5
8 wall Window (65) 24 Door (85) 32
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31
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IRC 24" Fully Sheathed Method
IRC R602.10.5

• For fully sheathed walls, IF
• Max opening height next to bracing
  is 65 of wall height
• permits use of
• 5-0 window
• Corner details are
• followed as given

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Continuous WSP SheathingTable R602.10.5

• Max opening height 85 of H
• 85 X 8 81.6 or 6 9
• 9 91.8 or 7 8
• 10 102 or 8 6
• a door or
• large window

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Corner Framing Detail (Typ.)
16d nail at 24" o.c.
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Depends on the Infill Panels Used
Fully Sheathed in Structural Panels (R602.10.5)
Infill with foam, fiberboard, laminated kraft
paper.
24 wide bracing
48 wide bracing
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Depends on the Infill Panels Used
Fully Sheathed in Structural Panels (R602.10.5)
Infill with foam, fiberboard, laminated kraft
paper.
24 wide bracing
48 wide bracing
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Narrower Than 24 Inches?

• Prefabricated Bracing

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Narrower Than 24 Inches?

• Prefabricated Bracing

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Narrower Than 24 Inches?

• Prefabricated Bracing
• APA Narrow Wall Bracing Method

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APA Narrow Wall Bracing Method

• Developed at the request of builders who wanted
  site built narrow bracing solutions

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APA Narrow Wall Bracing Method

• 1991 - King County, WA Recognition
• Western Washington
• Seattle to Portland
• Utah
• Kansas City
• Texas

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APA Narrow Wall Bracing Method

• 2004 Adopted by the International Residential
  Code
• Passed final hearings
• May 2004

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APA Narrow Wall Bracing Method
2004 Supplement to the 2003 IRC and The 2006 IRC
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IRC 2006See page 140, Fig. R602.10.6.2Flip
back to page 138 Table R602.10.5Read footnote
c. It describes the APA Method
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Alternate Braced Method Extended Header
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Alternate Braced Method APA Narrow Wall
Bracing Method
Inside Elevation
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Outside Elevation
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IRC 24 Wide Bracing (Fully Sheathed Method)
24"
24"
24"
Comparison to what is in the IRC
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Summary Of Test Results

• IRC Braced Wall Segment
• Average Maximum Load 3004 lb
• APA Narrow Wall Bracing Method
• Average Maximum Load 4351 lb
• Source APA Report T2003-48

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Summary Of Test Results
Load
(lbs)
Displacement - Inches
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APA Narrow Wall Bracing Method
Outside Elevation
3" x 11-1/4" min. header built-up, solid sawn,
glulam, etc.)
16" min. for 8' height 18" min. for 9' height
20" min. for 10' height
See typ. Corner framing detail.
Anchor bolts and plate washers, typ.
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APA Narrow Wall Bracing Method
Outside Elevation
3" x 11-1/4" min. header built-up, solid sawn,
glulam, etc.)
16" min. for 8' height 18" min. for 9' height
20" min. for 10' height
See typ. Corner framing detail.
Anchor bolts and plate washers, typ.
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Braced Wall Segments
One braced wall segment
Braced wall segment per R602.10.5
No. of jack studs per code
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Sheathing/Header Nailing
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Top Corner(Front View)
8d nails in 3" o.c. grid pattern
8d nails 3" o.c. to each stud
11 ¼"
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Top Corner(Back View)
16d nails at 24 inches o.c.
1000 Strap
Fasten top plate to header w/ two rows of 16d
sinkers 3" o.c.
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Corner Details (APA Method)
16d nail at 24" o.c.
Portal frame wall segment
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Corner Details (APA Method)
16d nail at 12" o.c.
Portal frame wall segment
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Corner Details (APA Method)
16d nail at 24" o.c.
Portal frame wall segment
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Corner Details (APA Method)
16d nail at 12" o.c.
Portal frame wall segment
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IRC 24" Fully Sheathed Method (Corner Framing)
16d _at_ 12" o.c.
(No portal frame)
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IRC 24" Fully Sheathed Method (Corner Framing)
16d _at_ 12" o.c.
8d _at_ 6" o.c.
(No portal frame)
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Base View
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Inside Base View
3/16" x 2" x 2" plate washers
Anchor bolts per code
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Header Between Openings(If Counted as a Bracing
Unit)
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Header Between Openings(If Counted as a Bracing
Unit)
3" o.c. nailing
16" minimum
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Code Accepted System
Continuous Foundation
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Continuous Foundations (Sill Plate Connections)
c
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Continuous Foundations (Sill Plate Connections)
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What About Raised Floors?
Requests from Builders

• Over basements and crawl spaces
• Second story bracing
• Sunrooms, etc.

Approved 2007 Suppl. to 2006 IRC
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APA Raised Floor Testing
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APA Raised Floor Testing
Lumber Joists Rim
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APA Raised Floor Testing
I-joists OSB Rimboard
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APA Raised Floor Testing
I-joists I-joist Rim
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Raised Floor Sill Connections(Framing Anchor
Option)
c
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Raised Floor Sill Connections(Framing Anchor
Option)
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Raised Floor Testing
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Raised Floor Sill Connections(Framing Anchor
Option)
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Raised Floor Sill Connections(Panel Overlap
Option)
c
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Raised Floor Sill Connections(Panel Overlap
Option)
3" o.c. nailing
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Raised Floor Sill Connections(Panel Overlap
Option)
Nailing into band joist
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Raised Floor Sill Connections(Panel Overlap
Option)
Nail sole plate, per R602.3(1)
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What About Raised Floors?
Check Local Building Officials
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Alternative material, design and methodsR104.11

• Allows for material that can be shown to be
  equivalent to what is currently in the existing
  code.

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Summary of Bracing Widths
Nonstructural panel infill sheathing
48"
48"
R602.10.1
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Summary of Bracing Widths
Nonstructural panel infill sheathing
Solutions for houses that are fully sheathed w/
structural panels
48"
24"
48"
24"
R602.10.1
R602.10.5
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Summary of Bracing Widths (8 tall walls shown)
Nonstructural panel infill sheathing
Solutions for houses that are fully sheathed w/
structural panels
48"
24"
16"
16"
48"
24"
R602.10.1
R602.10.5
APA Method
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Summary APA Method
Fully sheathed walls are required
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Limitations
Limited to -Garages only -Low seismic (SDC
A-C) -1st story or 1st of 2 story
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Fully-Sheathed Bracing Methods
Summary

• Builder Focused
• NAHB RC Developed (IRC 24" Method)
• Builder requested (APA Method)
• Framer friendly
• Typical construction methods and materials
• Easy to inspect
• Helps solves the narrow bracing problem

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Benefits of Fully Sheathed Homes

• Stronger walls minimize racking

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Benefits of Fully Sheathed Homes

• Stronger walls minimize racking
• Provides solid nail base for siding

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Benefits of Fully Sheathed Homes

• Stronger walls minimize racking
• Provides solid nail base for siding
• Helps reduce callbacks
• Drywall cracks / nail pops

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Benefits of Fully Sheathed Homes

• Stronger walls minimize racking
• Provides solid nail base for siding
• Helps reduce callbacks
• Drywall cracks / nail pops
• Siding waviness

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Benefits of Fully Sheathed Homes

• Stronger walls minimize racking
• Provides solid nail base for siding
• Helps reduce callbacks
• Drywall cracks / nail pops
• Siding waviness

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Benefits of Fully Sheathed Homes

• Stronger walls minimize racking
• Provides solid nail base for siding
• Helps reduce callbacks
• Drywall cracks / nail pops
• Siding waviness
• Reduces jobsite damage and vandalism
• Reduces "hidden" costs of repairs
• and replacement

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For Maximum Design Flexibility

• Fully Sheath with Plywood or OSB

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Continuous Sheathing Garage Openings
FULLY SHEATHED
Garage only, supporting roofwith 3 psf covering.
41 Aspect Ratio (24" min.) Table R602.10.5,
footnote b
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Continuous Sheathing Garage Openings Extended
Header Option
Garage only, permitsstory above
2006
61 Aspect Ratio (16" min.) Table R602.10.5,
footnote c
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Continuous Sheathing Whole House, R104.11
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www.apawood.org
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www.APACAD.org
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Order from ICC 800/786-4452
or www.iccsafe.org/store
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APA Wood Universitywww.wooduniversity.org

• Web-based instructional courses
• Modules on various engineered wood topics
• Self-paced with test your knowledge questions
• Earn AIA or AIBD credits

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Questions?
Apawood.org
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Research and Development

• 1989 - Narrow wall testing

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Portal Frame with Hold-downs
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Portal Frame with Hold-downs
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Sturd-I-Frame with Hold-downs
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16 APA Sturd-I-Frame (w/ Hold-downs)
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24 APA Sturd-I-Frame (w/ Hold-downs)
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Engineering Values

• Design values were derived. These are based on
  the load and deflection behavior observed, making
  the Sturd-I-Frame suitable for engineered
  applications too.

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IRC Wall Bracing Solutions