1. Disaster Resilience & Durability
October 8, 2014

2. Washington, IL
November 2013

3. Washington, IL
November 2013

4. Washington, IL
November 2013

5. Evansville, IN
November 6, 2005

6. Evansville, IN
November 6, 2005

7. Evansville, IN
November 6, 2005

8. Evansville, IN
November 6, 2005

9. Evansville, IN
November 6, 2005

10. Evansville, IN
November 6, 2005

11. Evansville, IN
November 6, 2005

12. Evansville, IN
November 6, 2005

13. Evansville, IN
November 6, 2005

14. Designing for Durability
Roof Sheathing Attachment
Gable end connections
Cladding attachment Roof to wall connection
Wall to wall continuity
Wall sheathing attachment
Wall sheathing continuity Wall connection to sill plate Sill plate anchorage
Reference: APA Report M310

15. Flying Debris

16. Gable-end Framing Tie gable end walls back to the structure
Gable end truss top chord
Tension-tie strap, attach with (8) 10d common nails, each end of strap
Roof Trusses
(3) 10d Common
nails (typical)
Gable end truss bottom chord
2x4 flatwise blocking between truss bottom chords
2" x 4" continuous lateral brace
@ 6' on center. Lateral brace sized to extend from end wall to over 3 interior trusses plus 6".

17. Components and Cladding
Resisting Pressure on
Components and Cladding
Sheath gable end walls with wood structural panels, such as plywood or oriented strand board (OSB)
Gable end truss top
8d Common nails - 4" on center perimeter of
panel
chord
Wood structural panel sheathing
Gable end truss vertical web member
8d Common nails - 6" on center along intermediate framing
8d Common nails - 4" on center perimeter of panel nailed to the top of the double top plate
Gable end truss
bottom chord

18. Wind Pressure Resistance
(APAform TT-105)
Table 1. Maximum wind speed (mph - 3 second gust) permitted for wood structural panel
sheathing used as wall covering to meet IRC Table R301.2(2) requirements1, 2, 3
MINIMUM NAIL
Minimum Wood Structural Panel Span Rating
Minimum Nominal Panel Thickness (inches)
Wall Stud Spacing (inches)
PANEL NAIL SPACING
MAXIMUM WIND SPEED (MPH)
Size
Penetration
Edges
Field
Wind Exposure Category --
(inches)
(inches o.c.) B C D
6d (0.113"
x 2.0")
1.5
24/0
3/8 16 6 12
110 90 85
24/16
7/16
100
150
125
8d (0.131"
x 2.5")
1.75
130
105
24 or less
Panel strength axis parallel or perpendicular to supports.
Three-ply plywood sheathing with studs spaced more than 16 inches o.c. shall be applied with panel strength axis perpendicular to supports.
Table is based on wind pressures acting toward and away from building surfaces per R301.2, lateral bracing requirements shall be in accordance with R

19. Wall Sheathing Nail Base For Siding Siding attachment at energy
efficient corners
Attachment base for utility
vents, siding trim, etc.

20. Smooth Shank and Screw Shank (Dia)
WSP Sheathing As A Nail Base
Withdrawal Load (Pounds)1
Plywood or OSB
Performance
Category
Ring Shank Nails (Dia.)
Wood Screws (Gauge)
Smooth Shank and Screw Shank (Dia)
.097
.113
.120
.128
.135 #7 #8 #9
.131
7/16 38 45 48 51 53 61 66 72 11 12 13
15/23 or 1/2 41 54 57 65 71 77 14
19/32 or 5/8 52 64 69 73 85 90 97 15 16 17
See APA TT-109 for footnotes and complete table
Reference: APA TT-109

21. Wall Sheathing
New Table in 2015 IRC

22. Wall Bracing Resources
Item no. 7102S12
Publication F430

23. Load Path 2. Transfer to roof 3. Connections 1. Load on wall
4. Transfer to wall
5. Transfer
to foundation

24. Lateral Forces Wind Seismic Force = Pressure x Area Force =
Mass x Acceleration

25. Resisted by hold-downs
Lateral Forces
Effects of Forces
Base Shear
Racking
Overturning
Resisted by Bracing
Resisted by Anchors
Resisted by hold-downs
& Dead Load

26. Lateral Forces
Racking

27. Lateral Forces
Base Shear

28. Lateral Forces Overturning February 2008 Macon Co. ‘Super Tuesday’
Tornado

29. Lateral Forces
Anchors
Hold-down

30. Bracing: BWP Location
BWP, BWL & Spacing
R202, R , R

31. Bracing: Required Length
Bracing Length Tables
2012 – Two bracing length tables
Table R (1) Table R (3)
Wind
Seismic
Required bracing length is the maximum of the two tables’ bracing length x all adjustment factors
R , Tables R (1), R (2), R (3) & R (4)

32. Bracing: Required Length
Bracing Requirements Based on Wind Speed – Adjustment Factors
Wind bracing adjustment factors are in Table R (2)
Wind exposure category
Eave-to-ridge height
Wall height
Number of braced wall lines
800-lb hold-down on top story
Application of interior gypsum board finish
Gypsum board fastening
Table R (2)

33. Bracing: Panel Material – Intermittent
Intermittent Bracing Methods:
LIB DWB WSP
BV-WSP
Let-in diagonal brace
3/4" Diagonal wood boards
3/8" Wood structural panel
7/16" Wood structural panel with
stone or masonry veneer
1/2" Structural fiberboard
1/2" Interior gypsum wallboard
or gypsum sheathing particleboard
3/8" Particleboard sheathing
SFB GB
PBS PCP HPS
Portland cement plaster on studs
7/16" Hardboard panel siding
Table R

34. Bracing: Panel Material – Intermittent
Intermittent Bracing Methods:
ABW PFH PFG
Alternate braced wall
Portal frame with hold-downs
Portal frame at garage door openings
in SDC A-C

35. Bracing: Panel Material – Continuous
Continuously sheathed wood structural panel
Continuously sheathed wood structural panel adjacent to garage openings
Continuously sheathed portal frame
Continuously sheathed structural fiberboard
Continuous Sheathing Bracing Methods:
CS-WSP
CS-G
CS-PF
CS-SFB
Table R

36. Bracing: Panel Material – Continuous
Method CS-WSP
Full-height sheathed wall segments having a length equal or greater than Table R are counted toward the total bracing length.
Wall minimum length is based on wall height and height of the adjacent clear opening.
Too Narrow
Table R

37. Bracing: Panel Material – Continuous
Method CS-WSP
Table R Minimum Length of Braced Wall Panels (in)
Method
Adjacent Clear Opening Height (ft)
Wall Height (ft) 8 9 10 11 12
CS-WSP 64 24 27 30 33 36 68 26 72 76 29 80 32 84 35 88 38 92 43 37 96 48 41
100 44 40
104 49 39
108 54 46
112 50 45
116 55
120 60 52
Table R

38. Bracing: Panel Material – Continuous
Method CS-G
Wood structural panel adjacent to garage opening
Full-height sheathed wall segments to either
side of garage openings
Roof covering dead loads of 3 psf or less (seismic requirement only)
Applied to one wall line of garage only
Garage Opening
12' Max
Panel length = bracing length
4:1 aspect ratio
R , Table R
H/4

39. Bracing: Panel Material – Continuous
Method CS-PF
Continuous portal frame
Walls on either or both sides of openings in garage may
have wall segment with a maximum 6:1 height-to-length ratio.
No hold-downs required
OK on raised floor
Top of header at 10' max
Top of wall at 12' max 
Panel length = bracing length
10' max
(12' max with
pony wall)
Garage Opening
H/6
Fully sheathed dwelling R

40. Bracing: Panel Material – Continuous
Method CS-PF
Figure R

41. Bracing: Panel Material – Continuous
CS-G
CS-PF 4

42. Bracing: Sufficient Length2' 4'
Method CS- WSP
Wind Direction
37'
CS-WSP
Bottom of Two Stories
90 mph SDC A
? NA
40'
40'
18"
48"
48"
27" 9'
Tables R (1)&(2), R , R

43. Bracing: Sufficient Length
Minimum Total Length of Braced Wall Panels Required Along Each Braced Wall Line
Braced Wall Line Spacing (ft)
Basic Wind Speed (mph)
Story
Location
Methods DWB, WSP, SFB, PBS, PCP, HPS
Method GB (double sided)
Method LIB
Continuous Sheathing 10 20 30 40 50 60
3.5 7
9.5
12.5
15.5
18.5
3.5 7
9.5
12.5
15.5
18.5 2 4
5.5
7.5 9
10.5 2
3.5 5 6
7.5 9
< 90 (mph) 10 20 30 7 13
18.5 7 13
18.5 4
7.5
10.5
3.5
6.5 9 40 24 24 14 12 50 60
29.5 35
29.5 35 17 20
14.5 17
Table R (1)

44. Bracing: Sufficient Length
Method CS- WSP
Can interpolate for BWL spacing or for wall height.
0.95 x 12′ = 11.4′ 2' 4'
CS-WSP
Bottom of Two Stories
90 mph
SDC A
11.4' NA
Total Bracing Length = 11.75′ vs. 11.4′ Required
Bracing is OK
40'
18"
48"
48"
27" 9'
Tables R (1)&(2), R , R

45. Wall Sheathing
Bracing Calculator

46. 2’2”
1’8” 2’
3’ 2’ 2’
2’ 2’ 3’ 2’
Wall Height = 9’ BWL Spacing = 24’ Roof-to-Eave = 14’
BWL Length = 54’-10”

47. Simply Bracing

48. 2012 IRC Wall Bracing A team of experts was assembled…
and this is what we got!
28 pages of wall bracing provisions
9 adjustment factors to determine bracing lengths
Multiple wind speed and seismic tables
8 old bracing methods and 7 new ones
Drywall on inside of all bracing mandated
All bracing panels must be blocked
More bracing is needed
“When you add options, things get complicated!”

49. There was a simpler way to brace house designs?
Wall Bracing
What if…
There was a simpler way to brace house designs?

50. APA Simplified Wall Bracing Method
What is this method based on?
The components that control the performance of bracing are panel thickness and fasteners.
Since the 3/8" code minimum panel thickness is relatively seldom used, the APA method is based on the more commonly used 7/16" thickness.
Fasteners aren’t very expensive, so the APA method increases the frequency of the fastening along panel edges.
All exterior wall areas sheathed with Wood Structural Panels.
When APA put the three together, we discovered another level
of performance in CS-WSP.

51. APA Simplified Wall Bracing Method
What is this method based on?
12000
3d 5b
6b 100% 2d
10,000
10000
lbf
CS-PF resists 174% more load than WSP bracing
8,000
8000
lbf
CS-WSP resists 88% more load than WSP bracing
Load (lbf)
6,000
6000
lbf
4,000
4000
lbf
WSP wall bracing – Base case
2,000
lbf
2000
Diagonal bracing resists 31% of WSP load
0.5 1 3
APA Full-Scale 3D Wall Bracing Tests, Form T
Displacement (in.)

52. APA Simplified Wall Bracing Method
Streamlining the process
Four steps:
Check the system criteria, lateral support and limitations.
Determine required bracing length from Table 3 and apply wall height multiplier.
Identify full height wall sections and whether they meet the minimum lengths per Tables 1 and 2 and the distribution requirements.
Add all qualifying bracing panels from step 3 on each side of
the home and compare to step 2.

53. Bracing Calculation Example
The house must meet the system criteria
No side longer than 60 feet
Two stories or less
Wall heights ≤ 12 feet
Roof to eave height ≤ 15 feet
Wind speeds ≤ 100 mph
Check lateral support and foundations

54. Bracing Calculation Example
The design parameters
House depth – 40 feet Roof height ≤ 15 feet 9' first floor height
8' second floor height
Wind Exposure Category – B 90 mph wind zone
2nd Floor above garage Drywall inside of exterior walls

55. Bracing Calculation Example
2. Draw a rectangle around the house, measure each side.
LONG SIDE
LONG SIDE
TYPICAL WALL CORNER
SHORT SIDE
TYPICAL SEGMENTS OF WALL BETWEEN CORNERS
SHORT SIDE
TYPICAL SEGMENTS OF WALL BETWEEN CORNERS
CIRCUMSCRIBING RECTANGLE
CIRCUMSCRIBING RECTANGLE
FIRST FLOOR PLAN
SECOND FLOOR PLAN

56. Bracing Calculation Example
2. Draw a rectangle around the house, measure each side
…Go to Table 3 and determine amount of bracing

57. Bracing Calculation Example
2. Draw a rectangle around the house, measure each side
…Go to Table 3 and determine amount of bracing
…apply the wall height adjustment factor
11.4' x .95 = 10.83' required bracing

58. Bracing Calculation Example
3. Identify full-height sections on sides of house
Full height
Actual Length #
16”
16”
16”
24”
12”
22”
22”
12”
24”
32”
32”

59. Bracing Calculation Example
3. Determine if segments meet minimum bracing length

60. Bracing Calculation Example
3. Determine if segments meet minimum bracing length
TABLE 1
MINIMUM LENGTH OF BRACED WALL PANELS
Method
Opening Height
Wall Height
Minimum Length
Actual Length
Bracing Length
CS-PF
84”
* 8’
16”
16”
24”
CS-WSP 80” 9’
*Height to top of header
30”
32”
32”
16”
16”
16”
24”
12”
22”
22”
12”
24”
32”
32”

61. Bracing Calculation Example
3. Determine if segments meet minimum bracing length
… if walls are 8’ or 9', there is partial credit for short lengths

62. Bracing Calculation Example
3. Determine if segments meet minimum bracing length
… if walls are 8' or 9', there is partial credit for short lengths
TABLE 2
PARTIAL CREDIT FOR BRACED WALL PANELS
Method
Opening Height
Wall Height
Minimum Length
Actual Length
Bracing Length
CS-WSP
64” 9’
24”
24”
22”
CS-WSP
64” 9’
20”
22”
18”
16”
16”
16”
24”
12”
22”
22”
12”
24”
32”
32”

63. Bracing Calculation Example
4. Compile the amount of bracing on each side of house
24" + 24" + 22" + 18" + 32" + 32" + 18" + 22" = 192" = 16.0' eligible for bracing
Full height segment/too short
Actual Length
Qualified Bracing Unit #
# Contributing Length
16”
16”
16”
24”
12”
22”
22”
12”
24”
32”
32”

64. Bracing Calculation Example
16.0' > 10.83' Bracing checked!
16”
16”
16”
24”
12”
22”
22”
12”
24”
32”
32”

65. Construction Tips for Building Moisture Resistant Houses
Prevent Moisture Intrustion
Construction Tips for Building Moisture Resistant Houses
Understanding Mold
& Moisture Intrusion
Reference: APA Report A500

66. Prevent Moisture Intrusion
Moisture Control
Wetting Drying
Water
Buildup
Past
Recent Past
Present

67. Prevent Moisture Intrusion
Four D's of Wall Design
Deflection
Drainage
Drying
Durable

68. Prevent Moisture Intrusion
Drainage plane
Materials designed and
installed to drain water
Installation
Continuous
Spaced from cladding
Drain to opening

69. Prevent Moisture Intrusion
* Consult building wrap manufacturer for installation details
Wood structural
panel
Proper fasteners
12" overlap at corner and vertical joints
Overlap horizontal
joints 6"-12"
Tape all tears
Cut and wrap at openings
3" overlap
at foundation
Tape all joints
with air-barrier tape
BBH – Walls, Page 9

70. Prevent Moisture Intrusion
Buildabetterhome.org
Construction details for
preventing moisture intrusion.

71. Prevent Moisture Intrusion
Roof Wall Intersection

72. Prevent Moisture Intrusion

74. Prevent Moisture Intrusion
Buildabetterhome.org
Construction details for
preventing moisture intrusion.
Weather barrier
Use spacers to allow for drainage
Metal flashing

75. Prevent Moisture Intrusion
Proper Ventilation

78. Minimum Ventilation Requirements
Location
Construction
Net Free Area of Openings
Attic
No vapor retarder
1/150
Vapor retarder in ceiling
1/300
Balanced ventilation
Crawl Space
Vapor retarder ground cover and one vent opening within three feet of each corner
1/1500

79. Prevent Moisture Intrusion

80. Prevent Moisture Intrusion
Mold from Improper Ventilation

81. Prevent Moisture Intrusion
Freefrommold.org
Provides an annual inspection and moisture prevention regimen for homeowners.

82. www.apawood.org www.performancewalls.org
Thanks for Attending
Bob Clark, APA
Matthew Brown, APA