Today s Goals & Objectives

Today’s Goals & Objectives Understanding the need for bracing Understand the requirements for wall bracing in the 2012 IRC Be able to perform a desig...
Author: Aubrey Benson
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Today’s Goals & Objectives Understanding the need for bracing Understand the requirements for wall bracing in the 2012 IRC Be able to perform a design, plan review or inspection of bracing of a wood framed dwelling Illustrate some new tools for designing/reviewing wall bracing

“What’s the big deal with wall bracing? I have been building this way for 20 years and have never had a problem”

Prescriptive Residential Codes Why do we have a prescriptive code? How does it differ from an engineered design? What is the basis for the requirements? Where might it fall short?

Purpose of a Residential Code R101.3 “…to safeguard the public safety, health and general welfare through affordability, structural strength…and safety to life and property from fire and other hazards attributed to the built environment.”

Engineered Design vs. Prescriptive Construction Engineered Design • Design loads specific to each structure • Load resisting elements are designed using accepted engineering practice Prescriptive Construction • Generic loads for all structures within the scope of the code • Historical Performance • Non-traditional engineering methods

Prescriptive Code • Based on long standing custom • Historical performance • Typical construction materials • Typical building shapes

Typical?

Typical?

Average Home Size 2,434 ft² 2005 2,095 ft² 1995

1,660 ft² 1973 1,000 ft² 1950

Source: Characteristics of Single Family Housing; Housing at the Millennium

Last 12 Years 30

25

20

15

Under 1400 Over 3000

10

5

(Z) 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Residential Design Trends More wall openings Larger rooms

Large openings in floor diaphragms Weaker “non-structural” materials Unique “architectural features”

Smaller building materials Historical performance may not be applicable to modern construction

Why Do We Need Wall Bracing?

Overall Wind Effects

Load Path Wind forces depend on size of building 1 2

1

3

Graphics courtesy of APA-The Engineered Wood Association

The Sail Boat Story What makes a sail boat faster?

Building geometry affects the amount of wind force: • The more surface area, the higher the wind loads.

How does wall bracing work?

Wall Bracing Mechanics

Wall Bracing Mechanics

Wall Bracing Mechanics

Shear Wall Connections

Wall Bracing Connections

Lateral Loads

Wall Racking Provide Shear Walls or Properly Designed Wall Bracing

Lateral Load Damage: Racking

Lateral Load Damage: Racking

Foundation Sliding Anchor building to foundation using properly installed anchor bolts or other approved alternate

Lateral and Uplift: Overturning Provide holdowns at ends of shearwall sections

Lateral Load Damage: Overturning

Lateral Load Damage: Overturning

Review: Lateral Effects from Wind or Earthquake

Shear/Sliding

Racking

Overturning

Purpose of Wall Bracing

How Does the Wall Bracing System Work?

 A Braced Wall Panel keeps the wall square by

  



transferring shear from the top of the wall to the bottom Braced wall panels are built in a specific way Braced wall panel has a specific amount of resistance Panels are placed at specific locations within a braced wall line to resist the lateral loads - typically the ends of each braced wall line and at 25 ft o.c Braced wall lines are placed at specific locations within the structure

Wall Bracing Requirements of the 2012 IRC

2006 to 2009 Wall Bracing Revisions Re-format Allow greater flexibility Add more narrow methods Add illustrations Reduce math (eliminate percentages) Correct bracing amounts for wind resistance

2012 Wall Bracing Revisions Re-re-format Add/revise illustrations Further simplify Add CS-SFB bracing method Add BV-WSP bracing method for brick veneer in higher seismic regions Add Simplified Wall Bracing Method R602.12

2012 IRC Wall Bracing Format: R602.10. Braced Wall Lines: Location, offsets, and spacing Braced Wall Panels: Construction, location, number required, uplift load path Required length of bracing Braced wall panel construction methods Braced wall panel minimum lengths Braced Wall Line corner options Braced Wall Panel Connections Braced Wall Panels Support Braced Wall Panel Joints Cripple Wall Bracing Simplified Wall Bracing provisions

R602.10 Wall Bracing R602.10 Wall bracing. Buildings shall be braced in accordance with this section or, when applicable, Section R602.12. Where a building, or portion thereof, does not comply with one or more of the bracing requirements in this section, those portions shall be designed and constructed in accordance with Section R301.1.

R602.10 Wall Bracing How do you do that? 1. Place braced wall lines on structure 2. Place braced wall panels on the braced wall lines 3. Construct the braced wall panels correctly

How do you brace a house? Easy as 1-2-3 1. Place braced wall lines on house 2. Place braced wall panels on walls 3. Construct braced wall panels properly

Braced Wall Lines

R602.10 Wall Bracing R602.10.1 Braced wall lines. For the purpose of determining the amount and location of bracing required in each story level of a building, braced wall lines shall be designated as straight lines in the building plan placed in accordance with this section. – R602.10.1.1 Length of a braced wall line. – R602.10.1.2 Offsets along a braced wall line. – R602.10.1.3 Spacing of braced wall lines.

Length of Braced R602.10.1.1 Length of a braced wall line. The length of a braced wall line shall be the distance between its ends. The end of a braced wall line shall be the intersection with a perpendicular braced wall line, an angled braced wall line as permitted in Section R602.10.1.4 or an exterior wall as shown in Figure R602.10.1.1.

Braced Wall Lines: Offsets R602.10.1.2 Offsets along a braced wall line. All exterior walls parallel to a braced wall line shall be offset not more than 4 feet from the designated braced wall line location as shown Figure R602.10.1.1. Interior walls used as bracing shall be offset not more than 4 feet from a braced wall line through the interior of the building as shown in Figure R602.10.1.1.

Braced Wall Lines: Spacing R602.10.1.3 Spacing of braced wall lines. The spacing between parallel braced wall lines shall be in accordance with Table R602.10.1.3. Intermediate braced wall lines through the interior of the building shall be permitted.

Braced Wall Lines: Angled Walls R602.10.1.4 Angled walls. Any portion of a wall along a braced wall line shall be permitted to angle out of plane for a maximum diagonal length of 8 feet. Where the angled wall occurs at a corner, the length of the braced wall line shall be measured from the projected corner as shown in Figure R602.10.1.4. Where the diagonal length is greater than 8 feet, it shall be considered a separate braced wall line and shall be braced in accordance with Section R602.10.1.

Braced Wall Lines: Easy as 1-2-3 BWL is a straight line through the building plan view. They do not have to be on a wall

All exterior walls must be within 4’ of a BWL (4’ maximum offset permitted) BWL spaced a maximum of 60’ O.C.

Wall Bracing Example: BWL

Wall Bracing Example: BWL

Wall Bracing Example: BWL

Example: 1) All Exterior Walls Part of a BWL 60 ft 25 ft

20 ft 8 ft

40 ft 52 ft

12 ft

20 ft

60 ft

Example: 2) BWL Spaced a Max. of 60’ O.C. 60 ft 25 ft

20 ft 8 ft

40 ft 52 ft

12 ft

20 ft

60 ft

Example: 3) 4’ Max. Offset from BWL 60 ft 25 ft

20 ft 8 ft

40 ft 52 ft

12 ft

20 ft

60 ft

Braced Wall Panels:

Where do they go? How do you build them?

≤ 25’

≤ 25’

≤ 25’

Braced Wall Panels: What are they? 1. Intermittent

2. Continuous

3. Narrow Alternates

Intermittent Wood Structural Panel Bracing

Same 8 Braced Wall Panel Methods: Intermittent BWP – R602.10.2 1. LIB - 1x4 Let in Brace 2. DWB - Diagonal Wood Boards 3. WSP - Wood Structural Panels 4. SFB - Structural Fiberboard 5. GB - Gypsum Board 6. PBS - Particleboard 7. PCP - Portland Cement Plaster 8. HPS - Hardboard Panel Siding

Braced Wall Panels: Table R602.10.2

Intermittent Bracing Methods

R602.10.2 Intermittent braced wall panel construction Method LIB: 1x4 Let In Bracing Installed at an angle of 45°- 60° from horizontal Min wall length = 8’-6” to 5’-1” for 8’ wall 2-8d nails at each stud and plate

R602.10.2 Intermittent braced wall panel construction Method LIB continued: Metal Wall Brace Installed at an angle of 45°- 60° from horizontal Min wall length = – 5’-0” for WB for 8’ wall – 5’-6” for RCWB for 8’ wall

Install in pairs in “X” or “V” for flat strap style Install only one for “let in” style Nailing to each stud and plate per manufacturer

Braced Wall Panels: LIB

Braced Wall Panels: LIB

R602.10.2 Intermittent braced wall panel construction Method WSP: Wood Structural Sheathing Min wall length = 48” 3/8” min thickness OSB or Plywood 6” O.C. edge nailing 12” O.C. field nailing

WSP Fastening

R602.10.2 Intermittent braced wall panel construction Method SFB: Structural Fiberboard Sheathing Min wall length = 48” 1/2” min thickness structural fiberboard 3” O.C. edge nailing 6” O.C. field nailing All Panel Edges to be blocked Fasteners: •1½” galv. roofing nail •8d common nail

Method SFB: Structural Fiberboard Sheathing

R602.10.2 Intermittent braced wall panel construction Method GB: Gypsum Board 1/2” min thickness Fastening: Nails or screws at 7″ spacing at panel edges including top and bottom plates; for all braced wall panel locations for exterior sheathing nail or screw size, see Table R602.3(1); for interior gypsum board nail or screw size, see Table R702.3.5

Min wall length = 48” for double sided

Min wall length = 96” for single sided

Interior Gypsum Board Fastening

b. Screws shall be in accordance with Section R702.3.6.

R702.3.6 Fastening. Screws for attaching gypsum board to wood framing shall be Type W or Type S in accordance with ASTM C 1002 and shall penetrate the wood not less than 5/8 inch (16 mm).

Exterior Gypsum Sheathing Nailing: Table 602.3(1)

Other Methods Method DWB Diagonal Boards 5/8” minimum thickness •8d nails or 1¾” staples, •2 to each stud

PBS ” 1-1/2″ galvanized roofing nails or 8d common (2-1/2″ × 0.131) nails at 3″ spacing (panel edges) at 6 spacing (intermediate supports)

Other Methods Method PCP 1-1/2″, 11 gage, 7/16″ head nails at 6″ spacing or 7/8″, 16 gage staples at 6″ spacing

Method HPS Hardboard Panel Siding 0.092″ dia., 0.225″ head nails with length to accommodate 11/2″ penetration into studs at 4″ spacing (panel edges), at 8″ spacing (intermediate supports)

Brace-oProprietary Methods

Brace-o-ply

The Magic Bracing Company Braceville, USA

Brace-O-Ply

R602.10.2.1 Intermittent braced wall panel interior finish material Intermittent braced wall panels shall have gypsum wall board installed on the side of the wall opposite the bracing material. Gypsum wall board shall be not less than 1/2 inch in thickness and be fastened in accordance with Table R702.3.5 for interior gypsum wall board. Exceptions: 1. Wall panels that are braced in accordance with Methods GB, ABW, PFG and PFH. 2. When an approved interior finish material with an in-plane shear resistance equivalent to gypsum board is installed. 3. For Methods DWB, WSP, SFB, PBS, PCP and HPS, omitting gypsum wall board is permitted provided the length of bracing in Tables R602.10.1.2(1) and R602.10.1.2(2) is multiplied by a factor of 1.5.

Braced Wall Panels: Minimum Lengths Minimum Lengths: Table R602.10.3.1

Partial Credit: Table R602.10.3

Alternate Braced Wall Panel Most braced wall panels have minimum lengths of 48” or more Alternate Braced Wall Panels allow lengths less than 48”

So what are our biggest challenges?

GARAGE RETURNS

Garage Openings

GARAGE RETURNS Usually the weakest part of the building Typical width of 12”-24” Less than 2’-4” minimum required by code for prescriptive methods or 4:1 when supporting light roof only

Not enough wall space

Effect of Narrow Panels

Effect of Narrow Panels

Effect of Narrow Panels

Effect of Narrow Panels

Alternate Braced Wall Panel Most braced wall panels have minimum lengths of 48” or more Alternate Braced Wall Panels allow lengths less than 48” To make up for reduced width, have to have restraint to keep from overturning

ABW Type 1: One Story Building Replaces 4’ Braced Wall Minimum Length of 2’-4” Maximum Height of 12’ Sheath with 3/8” min W.S.P. 6” O.C. 8d edge nailing 12” O.C. 8d field nailing 2 Anchor Bolts 2 Holdowns Reinforced Foundation

ABW Type 2: First Story of TwoStory Building All the requirements of Type 1 plus: Nail at 4” o.c. at edges instead of 6” o.c. 2 Holdowns Three Anchor Bolts

Figures instead of text

ABW Minimum Widths of Alternate Braced Wall Panel Minimum Widths & Tie-Down Forces of Alternate Braced Wall Panels

Height of Braced Wall Panel Sheathed Width Seismic Design Category and Windspeed

8 ft

9 ft

10 ft

11 ft

12 ft

Tie-Down Force (lb)

2'-4"

2'-8"

2'-8"

3'-2"

3'-6"

R602.10.6.1, Item 1

1800

1800

1800

2000

2200

3000

3000

3000

3300

3600

SDC A-C Windspeed < 110 R602.10.6.1, Item 2

Sheathed Width

R602.10.6.1, Item 1 SDC D (all) Windspeed < 110 R602.10.6.1, Item 2

8 ft

9 ft

10 ft

11 ft

12 ft

2'-8"

2'-8"

2'-8"

3'-2"

3'-6"

1800

1800

1800

---

---

3000

3000

3000

---

---

Simpson Components from T-WALLBRACE

Method PFH •Portal with holdowns •Replaces 4’ of braced wall panel •Must be adjacent to a window or door opening with a full-length header

PFH Alternate Panel Size • Height of not more than 10 feet • One story buildings – – minimum length of 16”

• First of two story buildings – – minimum length of 24”

PFH Sheathed on one face with a single layer of 3/8” minimum-thickness wood structural panel sheathing Nailed with 8d common or galvanized box nails in accordance with Figure R602.10.6.2.

PFH The wood structural panel sheathing extends up over the solid sawn or gluedlaminated header and is nailed in accordance with Figure R602.10.6.2. The header extends over and rests on studs at each side of opening.

PFH The clear span of the header not less than 6’ and not more than 18’ in length. A 1000 pound strap installed from the header to the inner studs opposite the sheathing.

1000 LB. STRAP INSTALLED TO FRAMING AND HEADER OPPOSITE SHEATHING

PFH One anchor bolt not less than 5/8” diameter installed in the center of a triple sill plate Embedded strap type tie-down device (holdown) with a min. capacity of 4,200 lbs. installed to the studs at each end of the panel.

PFH Panels supported directly on a foundation or on floor framing supported directly on a foundation, which is continuous across the entire length of the braced wall line. The foundation reinforced with not less than one No. 4 bar top and bottom.

PFH

Portal Frame Garage (PFG): R602.10.3.4 (Intermittent) Minimum 3” x 11¼” Continuous Header

Sheathing Nailed to Header with 8d Nails in 3” Grid Pattern

2x Top Plate 1000 lb Header Strap 2 Rows of 16d Sinkers Nails at 3” O.C. Min (2) 2x4 Minimum Width: 8-ft = 24-in 9-ft = 27-in 10-ft = 30-in 7/16” Min. Thickness Wood Structural Panel Sheathing Sheathing Nailed to all Studs, Plates, Blocking with 8d Common Nails at 3” O.C.

Full Height Outer Stud Nailed to Header with 6-16d Sinkers

Splices Shall Occur Within 24” of Mid-height and Edges Shall be Blocked

10’ Max

Two Anchor Bolts with 2½”x2½”x3/16” Plate Washers

• SDC A-C • Adjacent to Garage Door Opening • Directly on Foundation

Use wall length x 1.5 when determining bracing amounts

Method PFG

Simple right? Problems anywhere else?

Challenges with minimum panel width?

Continuously Sheathed Wall IRC Introduced new bracing concept All areas of all walls fully sheathed with wood structural panel sheathing, including above and below all openings – Lengths less than 4’ allowed – Reduced bracing amounts allowed – Specific exemption for garage return

Braced Wall Panels: Continuous Sheathing – R602.10.4 3/8” WSP Sheathing Above and Below all Openings 6”/12” O.C. Nailing

Similar Table for Continuous Methods

Continuously Sheathed Method: Minimum Lengths

2009 Req’d Length Table

Continuously Sheathed Method: Minimum Lengths (2012)

Continuously Sheathed Method Special corner framing Figure R602.10.4.4(1)

Continuously Sheathed Method Special corner framing 24” panel each side of corner

Continuously Sheathed Method Special corner framing not present

Continuously Sheathed Method Special corner framingfirst panel doesn’t meet width rqmts

Continuously Sheathed Method Special corner framingFirst panel not at corner

Continuously Sheathed Method Special corner framing 800-pound hold-down fastened to foundation or framing below Straps to framing below Anchor connecting to foundation

Effect of Narrow Panels

Continuously Sheathing: 3 Primary Benefits Braced wall panels can be narrower than 48” Braced wall lengths are reduced Method CS-G can be used at garages of one-story homes Method CS-PF can be used at openings

What if I STILL can’t meet the min. braced wall panel requirements? Garage returns too small? Windows too close to corners? Too much glass on back/front of

house?

Narrow Continuous Methods

Continuously Sheathed - Garage Wall supporting light framed roof only Adjacent to a garage 3/8” minimum Continuous WSP One wall of a garage only 10-ft max Height No special construction req’d Wall Height

Min. Length

8-ft

24-in

9-ft

27-in

10-ft

30-in

CS-PF Walls on either or both sides of openings attached to fully sheathed dwellings shall be permitted to be built similar to PFG EXCEPT •a single bottom plate is used •two anchor bolts are placed at 1/3 points of sill plate.

CS-PF •Tie-down devices are not required •The vertical wall segment has a minimum width per Table R602.10.4.2 W

(H/W≤6)

H

Continuous Portal Frame (CS-PF): R602.10.4.1.1 Minimum 3” x 11¼” Continuous Header

Sheathing Nailed to Header with 8d Nails in 3” Grid Pattern

2x Top Plate 1000 lb Header Strap 2 Rows of 16d Sinkers Nails at 3” O.C. Min (2) 2x4 Minimum Width: 8-ft = 16-in 9-ft = 18-in 10-ft = 20-in 3/8” Min. Thickness Wood Structural Panel Sheathing Sheathing Nailed to all Studs, Plates, Blocking with 8d Common Nails at 3” O.C.

Full Height Outer Stud Nailed to Header with 6-16d Sinkers

Splices Shall Occur Within 12” of Mid-height and Edges Shall be Blocked

Foundation: Two Anchor Bolts with 2”x2”x3/16” Plate Washers Wood Floor: Two 670-lb Framing Anchors or Overlapped Sheathing

10’ Max

Use actual wall length when determining bracing amounts

CS-PF Alternate Anchorage for Upper Story Walls

Continuous

Intermittent

Braced Wall Panels: Narrow Alternates Alternate Braced Wall (ABW), R602.10.3.2 Portal Frame with Hold-Downs (PFH), R602.10.3.3 Portal Frame at Garage Opening (PFG), R602.10.3.4 Continuous Sheathed Portal Frame (CS-PF), R602.10.4.1.1 Continuous Sheathed at Garage Opening (CS-G), R602.10.4

BIG CHANGE: AMOUNT OF BRACING No longer just a percentage (16%) Based on either • BWL spacing for wind • BWL length for seismic

Wall Bracing Amounts

Wall Bracing Amounts

Wall Bracing Amounts

Wall Bracing Amounts

Wall Bracing Amounts

Wall Bracing Amounts

Wall Bracing Amounts

2009 IRC Wind Hazard Map

Amount of Bracing: WIND R602.10.1.2(1)

SEISMIC R602.10.1.2(2)

A) Amount of Bracing: Table R602.10.1.2(1)

A) Amount of Bracing: Table R602.10.1.2(1)

Adjustment Factors •Wind Force

•Projected Area

•Bracing Strength

Adjustment Factors: Exposure

Wind Exposures: Consult your local building department for site classification!

Adjustment Factors: Exposure Exposure B Numerous closely spaced obstructions having the size of single-family dwellings or larger.

Adjustment Factors: Exposure Exposure C Open terrain extending more than 1500 feet in any quadrant. Exposure C extends 600 feet into adjacent exposure B type terrain. Includes flat open country, grasslands, and shorelines in hurricane prone regions.

Adjustment Factors: Exposure Exposure D Exposed to wind flowing over open water for a distance of at least 1 mile. Extends inland 1500 feet. Excludes shorelines in hurricane prone regions. Includes inland waterways and Great Lakes.

Adjustment Factors: Ridge Height

Eave-toRidge Height BWL Supporting Roof Above BWL Supporting Roof and One Story Above BWL Supporting Roof and Two Stories Above

Wall Height

Wall Height

Wall Height

Adjustment Factors: Wall Height • 0.90 for 8’

• 1.00 for 10’

• 0.95 for 9’

• 1.10 for up to 12’ Eave-toRidge Height

BWL Supporting Roof Above BWL Supporting Roof and One Story Above BWL Supporting Roof and Two Stories Above

Wall Height

Wall Height

Wall Height

Adjustment Factors: No. of BWLs

BWL C

BWL Spacing

BWL B BWL Spacing

Number of BWLs

BWL A

Wall Bracing for Wind EXPOSURE CATEGORY B 30 FT MEAN ROOF HEIGHT 10 FT EAVE TO RIDGE HEIGHT 10 FT WALL HEIGHT 2 BRACED WALL LINES BASIC WIND SPEED

≤ 90 MPH

STORY LOCATION

MINIMUM TOTAL LENGTH (FEET) OF BRACED WALL PANELS REQUIRED ALONG EACH BRACED WALL LINE

BRACED WALL LINE SPACING (FT)

METHOD LIBf,h

METHOD GB (DOUBLE SIDED)g

METHODS DWB, WSP, SFB, PBS, PCP, HPS i

CONT. SHEATHING

10

3.5

3.5

2.0

2.0

20

7.0

7.0

4.0

3.5

30

9.5

9.5

5.5

5.0

40

12.5

12.5

7.5

6.0

50

15.5

15.5

9.0

7.5

60

18.5

18.5

10.5

9.0

60 X 30 Bldg. 2 braced wall lines, Spacing = 60 feet Bracing req’d for WSP = 10.5’ Total bracing = 2 X 10.5 = 21’

Wall Bracing for Wind EXPOSURE CATEGORY B 30 FT MEAN ROOF HEIGHT 10 FT EAVE TO RIDGE HEIGHT 10 FT WALL HEIGHT 2 BRACED WALL LINES BASIC WIND SPEED

≤ 90 MPH

STORY LOCATION

MINIMUM TOTAL LENGTH (FEET) OF BRACED WALL PANELS REQUIRED ALONG EACH BRACED WALL LINE

BRACED WALL LINE SPACING (FT)

METHOD LIBf,h

METHOD GB (DOUBLE SIDED)g

METHODS DWB, WSP, SFB, PBS, PCP, HPS i

CONT. SHEATHING

10

3.5

3.5

2.0

2.0

20

7.0

7.0

4.0

3.5

30

9.5

9.5

5.5

5.0

40

12.5

12.5

7.5

6.0

50

15.5

15.5

9.0

7.5

60

18.5

18.5

10.5

9.0

60 X 30 Bldg. 3 braced wall lines, Spacing = 30 feet Bracing req’d for WSP = 5.5’ Total bracing = 3 X 5.5 = 16.5’ (less than 21’ required)

Adjustment Factors: 800-Pound Tie-Down 0.80 for top-most story only Each end of each BWP in BWL Fastened to foundation or framing below Straps to framing below Anchor connecting to foundation

Adjustment factor: Gypsum on inside face of BWP f.

Bracing lengths are based on the application of gypsum board finish (or equivalent) applied to the inside face of a braced wall panel. When gypsum board finish (or equivalent) is not applied to the inside face of braced wall panels, the tabulated lengths shall be multiplied by the appropriate factor from the following table:

Bracing Method Method LIB Methods DWB, WSP, SFB, PBS, PCP, HPS

Adjustment Factor 1.8 1.4

Seismic Bracing Table

Seismic adjustments all in one table

A) Amount of Bracing: R602.10.1.2 Length of Bracing In no case shall the minimum total length of bracing in a braced wall line, after all adjustments have been taken, be less than 48 inches total.

Braced Wall Panel Placement Easy as A…..B……C A. Amount (LENGTH) of bracing B. Spacing between panel edges C. Placement at ends of wall lines

A) Amount of Bracing A

B

C

Amount = A + B + C + D (Each segment must meet minimum width rqmts.)

D

B) Braced Wall Panel Spacing C) Braced Wall Panel at End of Wall

R602.10.2.2 Locations of braced wall panels. A braced wall panel shall begin within 10 feet from each end of a braced wall line as determined in Section R602.10.1.1. The distance between adjacent edges of braced wall panels along a braced wall line shall be no greater than 20 feet as shown in Figure R602.10.2.2.

BWP Spacing and End Distance

Mixing Bracing Amounts Mixing of bracing method shall be permitted as follows: 1. Mixing bracing methods from story to story is permitted. 2. Mixing bracing methods from braced wall line to braced wall line within a story is permitted, except that continuous sheathing methods shall conform to the additional requirements of Sections R602.10.4 and R602.10.5. 3. Mixing bracing methods within a braced wall line is permitted only in Seismic Design Categories A and B, and detached dwellings in Seismic Design Category C. The length of required bracing for the braced wall line with mixed sheathing types shall have the higher bracing length requirement, in accordance with Tables R602.10.1.2(1) and R602.10.1.2(2), of all types of bracing used.

Blocking of Horizontal Joints R602.10.8 Blocking required at all horizontal joints in BWPs – Blocking may be omitted for WSP, SFB, GB, PBS, HPS when bracing amount is doubled – GB installed horizontally does not require blocking

R301.3 Story height. R301.3 Story height. Buildings constructed in accordance with these provisions shall be limited to story heights of not more than the following: 1. For wood wall framing, the laterally unsupported bearing wall stud height permitted by Table R602.3(5) plus a height of floor framing not to exceed 16 inches.

Stud Table

R301.3 Story height. Exception: For wood framed wall buildings with bracing in accordance with Tables R602.10.1.2(1) and R602.10.1.2(2), the wall stud clear height used to determine the maximum permitted story height may be increased to 12 feet without requiring an engineered design for the building wind and seismic force resisting systems provided that the length of bracing required by Table R602.10.1.2(1) is increased by multiplying by a factor of 1.10 and the length of bracing required by Table R602.10.1.2(2) is increased by multiplying by a factor of 1.20. Wall studs are still subject to the requirements of this section.

Construction Issues Overdriven Fasteners (APA TT-012) No Reduction if: – < 1/16” in dry conditions – Not more than 20% around perimeter > 1/16” up to 1/8” – Actual panel thickness less overdriving amount ≥ required panel thickness (i.e. 7/16” actual w/ 1/8” overdriven = 5/16” net thickness

Construction Issues Overdriven Fasteners (APA TT-012) If more than 20% around perimeter are overdriven by 1/16” or if ANY are overdriven by 1/8”, additional fasteners shall be driven to maintain the required shear capacity. Install one additional fastener for every two fasteners that are overdriven

Construction Issues Fastener Location Fasteners must be located a minimum of 3/8” from the edge of the panel

Connections Where joists are perpendicular to the braced wall lines above, blocking shall be provided under and in line with the braced wall panels. Where joists are perpendicular to braced wall lines below, blocking shall be provided over and in line with the braced wall panels. Where joists are parallel to braced wall lines above or below, a rim joist or other parallel framing member shall be provided at the wall to permit fastening per Table R602.3(1).

Connections Braced wall line sole plates shall be fastened to the floor framing and top plates shall be connected to the framing above in accordance with Table R602.3(1). Sills shall be fastened to the foundation or slab in accordance with Sections R403.1.6 and R602.11.

Connections R602.10.6 BWP connections – Table R602.3(1): 8d Box Nails 6” O.C. rim board/blocking to top plate below – Joist, full height blocking, or other framing member above and below BWPs

Connections Sole plate to joist or blocking at braced wall panels 3-16d (3½”×0.135”) at 16” o.c.

Rim joist to top plate, toe nail 8d (2-1/2″×0.113″) at 6″ o.c.

Connections 2. Where joists are parallel to a braced wall panel above or below, a rim joist, end joist or other parallel framing member shall be provided directly above and below the braced wall panel in accordance with Figure R602.10.6(2). Where a parallel framing member cannot be located directly above and below the panel, full-depth blocking at 16 inch (406 mm) spacing shall be provided between the parallel framing members to each side of the braced wall panel in accordance with Figure R602.10.6(2). Fastening of blocking and wall plates shall be in accordance with Table R602.3(1) and Figure R602.10.6(2).

Connections 3. Connections of braced wall panels to concrete or masonry shall be in accordance with Section R403.1.6.

Miscellaneous Bracing Provisions Figure R602.10.6(1) Perpendicular Framing

Miscellaneous Bracing Provisions Figure R602.10.6(2) Parallel Framing

R403.1.6 Foundation anchorage. Sill plates and walls supported directly on continuous foundations shall be anchored to the foundation in accordance with this section. Wood sole plates at all exterior walls on monolithic slabs, wood sole plates of braced wall panels at building interiors on monolithic slabs and all wood sill plates shall be anchored to the foundation with anchor bolts spaced a maximum of 6 feet on center.

R403.1.6 Foundation anchorage. Bolts shall be at least ½ inch in diameter and shall extend a minimum of 7 inches into concrete or grouted cells of concrete masonry units. A nut and washer shall be tightened on each anchor bolt.

IRC R403.1.6 Foundation Anchorage There shall be a minimum of two bolts per plate section with one bolt located not more than 12 inches or less than seven bolt diameters from each end of the plate section. Interior bearing wall sole plates on monolithic slab foundation that are not part of a braced wall panel shall be positively anchored with approved fasteners.

IRC R403.1.6 Foundation Anchorage Exceptions: 1. Foundation anchorage, spaced as required to provide equivalent anchorage to 1/2-inch-diameter anchor bolts.

IRC R403.1.6 Foundation Anchorage Exceptions: 1. Foundation anchorage, spaced as required to provide equivalent anchorage to 1/2-inch-diameter anchor bolts. 2. Walls 24 inches total length or shorter connecting offset braced wall panels shall be anchored to the foundation with a minimum of one anchor bolt located in the center third of the plate section and shall be attached to adjacent braced wall panels per Figure R602.10.5 at corners. 3. Walls 12 inches (305 mm) total length or shorter connecting offset braced wall panels shall be permitted to be connected to the foundation without anchor bolts. The wall shall be attached to adjacent braced wall panels per Figure R602.10.5 at corners.

Miscellaneous Bracing Provisions

Miscellaneous Bracing Provisions R106.1.1 Building official may require that construction documents include – – – –

Braced Wall Lines Braced Wall Panel location and length Bracing Method Foundation Requirements

Uplift at braced wall panels R602.10.1.2.1 Braced wall panel uplift load path. Braced wall panels located at exterior walls that support roof rafters or trusses (including stories below top story) shall have the framing members connected in accordance with one of the following: 1. Fastening in accordance with Table R602.3(1) where: 1.1 The basic wind speed does not exceed 90 mph, the wind exposure category is B, the roof pitch is 5:12 or greater, and the roof span is 32 feet or less, or 1.2 The net uplift value at the top of a wall does not exceed 100 plf. The net uplift value shall be determined in accordance with Section R802.11 and shall be permitted to be reduced by 60 plf for each full wall above. 2. Where the net uplift value at the top of a wall exceeds 100 plf, installing approved uplift framing connectors to provide a continuous load path from the top of the wall to the foundation. The net uplift value shall be as determined in Item 1.2 above. 3. Bracing and fasteners designed in accordance with accepted engineering practice to resist combined uplift and shear forces.

Uplift at BWP’s R602.10.1.2.1 Uplift load path required – Approved uplift framing connectors required at top and bottom of studs at braced wall panels when net uplift from R802.11 exceeds 100 plf

These loads are for framing 24” o.c. Divide by two for plf

Miscellaneous Bracing Provisions R602.10.6.2 BWP connections to roof – Top of rafter/truss to top of top plate ≤ 9¼”: no additional requirements (low seismic) – ≤ 14¼”: Figure R602.10.6.2(1) – ≤ 48”: Figures R602.10.6.2(2) or R602.10.6.2(3)

Miscellaneous Bracing Provisions R602.10.7 BWP support 1. BWP on cantilevered floor joists 2. BWP on elevated post or pier foundations 3. BWP on masonry stem walls a. Length ≤ 48”: reinforced per Figure R602.10.7 b. ABW and PFH not permitted on masonry

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Another Challenge

About That Great Room… Topics: – Framing for great room walls – Framing for 2 story entry area walls – Bracing in these areas – Alternative solutions

Great Room & Tall Wall Areas

Great Room & Tall Wall Areas IRC R602.10 – Bracing amounts based on 10’ wall heights

IRC R301.3 Exception – Can increase wall height to 12’ without engineered design provided length of bracing in Table R602.10.1 is increased by a factor of 1.2

IRC Table R602.10.6 – alternate wall panels up to 12’ height (SDC AC only)

IRC Table R602.3(5) – Limits bearing wall stud height to 10’

Great Room & Tall Wall Areas How do I build a great room wall? IRC 2006 R602.3.1 – Studs more than 10’ in height in accordance with Table R602.3.1 – Allows for certain size & grade stud heights up to 24’

IRC 2006 R602.8 -- Fireblocking – Requires horizontal blocking at intervals not exceeding 10 feet

IRC 2006 R602.10 – Bracing still applies! – Is it 1 story or 2? – What type of braced wall panels do I use?