Siding Attachment: Facts and Fantasies

Siding Attachment:
Facts and Fantasies
Derek A. Hodgin, RRC, RWC, REWC, RBEC, RRO, PE, CDT, CCCA;
and John C. Wylie, EI
Construction Science and Engineering, Inc.
218 East Main Street, Westminster, South Carolina, 29692
Phone: 864-647-1065 • Fax: 864-647-1076
E-mail: derekhodgin@constructionscience.org and john_wylie@constructionscience.org
2 9 t h RC I I n t e r n a t i o n a l C o n v e n t i o n a n d T r a d e S h ow • Ma rc h 2 0 – 2 5 , 2 0 1 4 H o d g i n a n d Wy l i e • 2 7
Abstract
The use of cementitious lap siding products has grown substantially over the past two
decades. In coastal environments, attachment of the siding on buildings is important to
minimize damages during code-defined wind events. When these buildings are the subject
of construction litigation, criticisms of attachment are common. Some experts opine that
complete removal and replacement of the siding is necessary due to attachment issues.
However, the authors believe that complete removal and replacement is rarely justified. This
presentation will provide the audience with a general knowledge base to correctly evaluate,
analyze, and formulate reasonable repairs regarding as-built siding attachment conditions.
Speaker
Derek Hodgin, RRC, RWC, REWC, RBEC, RRO, PE, CDT, CCCA – Construction Science and Engineering, Inc.
Derek Hodgin has over 20 years of experience as an engineering consultant. He
performs facility condition inspections, failure analysis, damage assessments, and forensic
engineering investigations of all types of structures. A licensed professional engineer in 18
states, Hodgin is also registered as an RRO, RRC, REWC, RWC, and RBEC with RCI, Inc.
His experience includes failure analysis of a wide variety of building envelope and roof systems.
A large number of his projects have included analysis of deficient construction cases,
including all aspects of the building envelope.
John C. Wylie, EI – Construction Science and Engineering, Inc.
John C. Wylie provides engineering services to the professional staff of his firm, primarily
in the areas of determination of deficient construction, structural analysis, and collapse
and damage investigations. He performs investigations and engineering analyses of
various types of building components used in high-wind environments, including roof coverings
and exterior wall claddings. Wylie’s academic career includes dual bachelor of science
degrees in physics and applied mathematics from Mansfield University of Pennsylvania and
an MS in civil engineering with a concentration in structures and mechanics from North
Carolina State University.
2 8 • Ho d g i n a n d Wy l i e 2 9 t h RC I I n t e r n a t i o n a l C o n v e n t i o n a n d T r a d e S h ow • Ma rc h 2 0 – 2 5 , 2 0 1 4
INTRODUCTION
Exterior cladding is a key element to
all buildings. The exterior cladding of a
structure can include different types of sidings
such as wood, hardboard, vinyl, and
cementitious lap siding. Over the past two
decades, the installation of cementitious lap
siding (also known as fiber cement board
siding) as an exterior cladding has grown
substantially. Specifically, fiber cement
board siding is now commonly installed on
single- and multifamily residential buildings,
as well as light commercial buildings
located in coastal environments.
Due to the increased use of fiber cement
board siding on buildings located in coastal
environments, attachment of the fiber
cement board lap siding has become closely
scrutinized. When these buildings are subject
to construction litigation, criticisms
of siding attachment are common. In fact,
some expert witnesses assert that when the
siding attachment is not installed in accordance
with the manufacturer’s installation
instructions, complete removal and replacement
of the siding is necessary.
Typically, expert witnesses rely on applicable
building codes, industry standards,
and manufacturer information to formulate
their opinions. Additionally, expert
witnesses use engineering judgment and
experience to correctly evaluate, analyze,
and formulate reasonable repairs regarding
the as-built siding attachment conditions
when necessary. This paper will provide
the distinction between real issues (facts)
and nonissues (fantasy) regarding siding
attachment that have become common in
construction litigation.
ATTACHMENT TERMINO LOGY
Like many other siding products, fiber
cement board siding can be blind-nailed
(concealed) or face-nailed (exposed). These
two attachment terms are consistently used
in building codes, industry standards, and
manufacturers’ installation instructions.
As shown in Figure 1, blind nailing
involves fasteners through the bottom
course of siding and covered by the course
of siding above. The heads of the fasteners
are concealed by the overlapping siding.
Face nailing involves fasteners driven
through the top course and bottom course
of siding where the planks overlap. The
heads of the fasteners are exposed.
BUILDING CODE REQUIREMENTS
In general, the intent of building codes
is to provide the design professional and/or
general contractor with minimum requirements
to which a building is to be constructed.
The minimum requirements in the
building code include a combination of prescriptive
and performance-based requirements.
By definition, prescriptive requirements
specifically state how a building is to
be constructed (i.e., attach the siding using
a 6d common nail that penetrates each wall
stud a minimum of one inch), while performance
requirements outline a minimum
level of building performance (i.e., the siding
shall resist a code-defined wind load of
130 mph).
Fiber cement board attachment was not
introduced into any of the building codes
until the 2003 International Residential
Code (IRC). Prior to the 2003 IRC, building
codes only provided attachment requirements
for other types of exterior cladding.
Building codes typically include alternate
attachment conditions, such as attaching to
light-gauge metal and wood stud wall framing.
Table 1 provides a summary of the fiber
cement board attachment requirements set
forth by the building codes for fasteners
installed into structural panel wall sheathing
and wood wall framing.
Siding Attachment:
Facts and Fantasies
2 9 t h RC I I n t e r n a t i o n a l C o n v e n t i o n a n d T r a d e S h ow • Ma rc h 2 0 – 2 5 , 2 0 1 4 H o d g i n a n d Wy l i e • 2 9
Figure 1 – Blind nailing and face nailing. Source: James Hardie Technical Bulletin
#171
Table 1 – Summary of building code fiber cement board siding.
As shown in Table 1, the attachment
requirements of the fiber cement board
siding were the same for the 2003 IRC2
and 2006 IRC.3 Similarly, the attachment
requirements of the fiber cement board siding
were the same for the 2009 IRC4 and
2012 IRC.5 A significant difference between
the 2003/2006 IRC requirements and the
2009/2012 IRC requirements is the reduction
of two fasteners to one fastener for
face nailing applications. Additionally, the
footnotes provided in the building codes
changed. Specifically, the 2003/2006 IRC
recommended a minimum fastener size
and head, whereas the 2009/2012 IRC
simply stated that the fastener dimensions
had to be in compliance with ASTM F1667,
Standard Specification for Driven Fasteners:
Nails, Spikes and Staples.6
As previously stated, the intent of the
building code is to provide the minimum
requirements for construction. With regard
to fiber cement board attachment, the building
codes provide the minimum type, size,
and location of fasteners; however, when
a structure is located in a high-wind area,
the design professional should evaluate
the attachment because the minimum prescriptive
requirements stated in the building
code may not be adequate to meet the
performance requirement to resist a codeprescribed
wind load. Additionally, alternate
fasteners not specifically addressed
in the building code may be considered an
improvement over the fasteners specified in
the code.
INDUSTRY STANDARDS
In general, industry standards are
accepted requirements followed by the
members of a particular industry and/
or discipline. Industry standards tend to
incorporate the state-of-the-art construction
practices and manufacturer literature
at that time. Some standards are specifically
referenced by the applicable building
codes (making them a code requirement),
while other standards are considered to
represent a nonmandatory “best-practices”
guide.
With regard to fiber cement board
attachment, the building codes do not provide
specific industry standard references.
However, there are additional sources of
information that do provide a best-practices
guide regarding the attachment of the fiber
cement board siding. One example is the
Journal of Light Construction’s JLC Field
Guide To Residential Construction: A Manual
of Best Practice (JLC Guide).7 This provides
general guidelines regarding the installation
of fiber cement board siding. Some of
the general guidelines provided in the JLC
Guide include:
• Fasteners should not be set below
the surface or overdriven into the
siding because it will reduce the
holding power.
• Specific fasteners should be used for
face-nailing or blind-nailing applications.
• Minimum dimensions for face nailing
and blind nailing are provided.
• Fasteners must penetrate wood
framing.
• Corrosion-resistant fasteners should
be used.
FEMA P-499, Home Builder’s Guide to
Coastal Construction, is another example
of a best-practices industry standard that
references the installation of fiber cement
board siding. For instance, FEMA P-4998
recommends that stainless steel fasteners
be used when the building is located within
3,000 feet of the ocean shoreline.
As described above, some of the general
guidelines recommended by the JLC
Guide and FEMA P-499 provide the design
professional and/or contractor with additional
information that may or may not be
provided in the building code or manufacturers’
literature. In regard to construction
litigation, these guides could be used by the
expert witness to supplement information
in the building code or the manufacturers’
literature. However, noncompliance with
best practices does not necessarily mean
that there was negligence by the design
professional and/or contractor.
MANU FACTURERs’ LITERATURE
When fiber cement board siding attachment
is the topic of construction litigation,
being able to locate and review a specific
manufacturer’s product literature is important.
The information contained within
the manufacturer’s product literature can
provide the expert witness with important
information regarding the attachment
requirements and if its product has been
subject to any evaluation testing. It is
important for the expert witness to review
the manufacturers’ literature that was current
at the time of application.
Typical installation instructions describe
acceptable substrates to which siding
can be attached, types of fasteners,
and dimensional tolerances regarding the
fastener location and condition of installed
fasteners relative to the fiber cement board
siding.9,10,11 These prescriptive requirements
are important to know when evaluating the
adequacy of the fiber cement board siding
attachment.
In addition to installation instructions,
some manufacturers will produce supplemental
documents that include best practices
and technical bulletins that discuss
alternate attachment details. Some of the
supplemental documents include additional
information regarding the use of blind- and
face-nailing combinations (i.e., double nailing)
and the use of alternative fasteners in
high-wind areas.1,12
CODE EVALUATION REPORTS
In order to verify product compliance
with the applicable building codes, manufacturers
will have their products evaluated
by a certified testing agency. The testing
agencies rely on the minimum requirements
in the building code and standardized testing
methods to produce a code evaluation
report. Compliance with the code evaluation
report becomes a building code requirement.
Prior to the International Building Code
and International Residential Code (the “I”
codes), there were several different code
evaluation agencies. Some of these code
evaluation agencies were specific to a particular
building code. It should be noted
that these code evaluation reports are not
code-referenced. The ideology behind the
code evaluation report is that manufacturers
would have their product tested to verify
compliance with a particular building code
or several building codes. Therefore, the
installation of the evaluated product would
comply with the applicable building code.
However, the code evaluation report for a
fiber cement board siding product that has
been tested and evaluated in accordance
with the 2003 IRC would not be in compliance
with the 2012 IRC. The evaluation
must be specific to the code with which the
manufacturer seeks compliance.
CON STRUCTION DEFECT
LITIGATION
As stated previously, due to the increase
of fiber cement board siding (especially in
coastal environments), attachment of the
3 0 • Ho d g i n a n d Wy l i e 2 9 t h RC I I n t e r n a t i o n a l C o n v e n t i o n a n d T r a d e S h ow • Ma rc h 2 0 – 2 5 , 2 0 1 4
fiber cement board siding has become a
topic of construction defect litigation. When
this occurs, an expert witness should identify
construction deficiencies or allegations
that are based on data collected during a
visual survey and an engineering analysis
based on the as-built conditions.
Typical Allegations
During the course of construction litigation,
the primary focus of the plaintiff
expert is to identify construction deficiencies
that require repair. Provided is typical
photographic documentation of allegations
regarding fiber cement board siding attachment
(see Figures 2 through 7).
According to some expert witnesses,
all the above-mentioned typical allegations
represent a construction deficiency because
they may deviate from applicable building
code, industry standards, and/or manufacturers’
installation instructions. It is the
opinion of the authors that, while conditions
may deviate from written instructions,
they do not always represent a construction
defect that requires a repair.
Data Collection
For an expert witness, data collection
relative to the fiber cement board siding
attachment is important. Specifically, data
collection provides the information that will
be used to determine the adequacy of the
as-built siding conditions. Provided below
are some of the important data needed to
evaluate the adequacy of the fiber cement
board siding attachment:
• Fastener type (length, shank diameter,
head diameter, shank type)
• H orizontal fastener spacing
2 9 t h RC I I n t e r n a t i o n a l C o n v e n t i o n a n d T r a d e S h ow • Ma rc h 2 0 – 2 5 , 2 0 1 4 H o d g i n a n d Wy l i e • 3 1
Figure 2 – Improper fastener type (not
listed in code evaluation).
Figure 3 – Inadequate fastener spacing (greater than 16 inches on center).
Figure 4 – Inadequate edge distance (less than 1 inch).
• Vertical fastener spacing
• Siding width and overlap (exposure)
• Fastener end/edge distance
• Measurement of overdriven/underdriven
fasteners
• Statistical count of fasteners into
framing
• Substrate type and thickness (typically
OSB or plywood)
• Species of wood framing (to estimate
specific gravity)
Fasteners come in different types and
sizes. With their installation instructions,
some manufacturers will provide recommended
fastener types and sizes that can
be used in the installation of their product.
However, it should be noted that alternate
fasteners, not specifically mentioned in the
installation instructions, could be used in
lieu of the recommended fasteners and meet
performance requirements of the building
code. However, an engineering analysis is
needed to determine adequacy. There are
expert witnesses that believe the installation
of fasteners not specifically referenced
in the installation instructions represents
a construction deficiency, such that complete
removal and replacement is needed.
However, some manufacturers provide literature
that specifically states alternate
fasteners may be used if the design professional
can prove that the alternate fasteners
are in compliance with the applicable
building code. This is referred to as an
equivalency analysis.
The horizontal and vertical fastener
spacing measurements are used to calculate
the tributary area (effective area) of the
fastener. The tributary area of the fastener
3 2 • Ho d g i n a n d Wy l i e 2 9 t h RC I I n t e r n a t i o n a l C o n v e n t i o n a n d T r a d e S h ow • Ma rc h 2 0 – 2 5 , 2 0 1 4
Figure 5 – Fasteners not into framing (less than 1 inch).
Figure 6 – Overdriven/underdriven
fasteners.
Figure 7 – Inadequate end distance.
is used during the engineering analysis. It
is the effective area that the fastener will be
responsible for in resisting a code-defined
wind load.
In their installation instructions, most
manufacturers will recommend end distances
and edge distances for fasteners.
These help to prevent the siding from cracking
when subjected to fastener installation,
siding shrinkage, or wind loads. It should
be noted that a fastener can be installed
within the manufacturer-recommended
end/edge distances; however, the likelihood
that the siding will crack will increase if
the fastener is installed closer to the end
and/or edge of the siding. The evaluation
of a siding failure, where the siding breaks
around the fastener due to outward rotation
and prying action, is not addressed by
this paper. Siding may be vulnerable to this
type of failure when blind nailing is used.
The risk of this type of failure increases
proportionally as the fastener gets closer to
the top edge.
As stated by most manufacturers in the
literature, and in some industry standards,
a fastener should be installed flush to the
top surface of the siding. Most manufacturers
and industry standards recommend
that a fastener should not be installed in an
underdriven or overdriven condition. In the
event that a fastener is underdriven or overdriven,
a supplemental fastener is typically
installed adjacent to the original fastener.
Regarding the engineering analysis, it
is important to determine the percentage of
fasteners that penetrated the wood framing
versus those that did not. This statistical
percentage, based on the number of fasteners
that penetrate the wood framing,
provides the expert witness with data that
can be used in determining an appropriate
repair, if considered to be necessary.
Engineering Analysis
It is uncommon for a structural engineer
to perform an engineering analysis on
the exterior siding attachment as part of
the original design process for a residential
structure. However, expert witnesses
may be required to perform an engineering
analysis on the adequacy of the as-built siding
attachment details during construction
litigation.
In order to adequately evaluate the asbuilt
condition of the fiber cement board
siding attachment, the expert witness needs
to compare the withdrawal resistance of the
as-built conditions to the code-prescribed
wind loads. The engineering analysis should
include design wind pressure calculations,
fastener withdrawal calculations, and comparing
the as-built condition of the siding
attachment to the code-defined wind load.
Depending on the applicable building
code to which the subject structure was
originally subjected, the expert witness
can calculate the design wind pressures
by using information provided in the building
code or by using the code-referenced
industry standard (i.e., ASCE 7). Expert
witnesses should calculate the design wind
pressures based on the information provided
in the building code that had been
adopted at the time of application. The
design wind pressure is dependent on the
wind speed, exposure category, height of
the building, and location on the building
(field or corner). If the expert witness has
to use a code-referenced industry standard,
more information about the structure may
need to be known in order to determine the
design wind pressures.
Determination of fastener withdrawal
is based on code-referenced industry standards.
For example, the “National Design
Specification for Wood Construction”
(NDS)13 is the standard that is commonly
used by expert witnesses to determine that
fastener withdrawal resistance. Fastener
withdrawal resistance is based on a mathematical
equation that takes into account
several factors that may affect the attachment
when subjected to different types of
loads, environmental conditions, fastener
types, and construction conditions. The
fastener withdrawal resistance determined
from the NDS is expressed in pounds per
inch of penetration into the wood substrate.
Therefore, one key factor in determining
fastener withdrawal resistance is determining
the depth of penetration of the fastener
into the wood sheathing and wood framing.
The type of wall sheathing, the species of
the wood framing, and the shank diameter
of the fastener are also considered.
When the design wind pressure calculations
and fastener withdrawal resistance
calculations have been performed,
the expert witness can compare the as-built
attachment conditions to the code-defined
loads. At this point of the engineering analysis,
the expert witness takes into account
the data that were collected to accurately
analyze the siding attachment. For example,
the vertical and horizontal spacing of
the fastener are used to determine the tributary
area of a fastener. The effective area
is needed to convert the design wind pressures
to fastener withdrawal requirements.
REPAIR RECOMMENDATION S
A reasonable repair regarding the
attachment of fiber cement board siding
is based on a complete review of the applicable
building code, industry standards,
and manufacturer literature, in addition to
correctly evaluating and analyzing the asbuilt
conditions of the siding attachment.
Based on the above-mentioned research
and engineering analysis, an expert witness
may choose between the following potential
repair options:
• No repairs
• Installation of supplemental fasteners
• Complete removal and replacement
A variety of conditions (i.e., environmental,
construction) can influence the type of
repair needed and can vary from case to
case. Depending on the results of the engineering
analysis, an expert witness may
recommend that a repair not be considered
necessary, even when deviations from the
manufacturer instructions exist.
If the engineering analysis reveals that
the as-built attachment details are insufficient
to resist code-defined wind loads, supplemental
fastening is the most common
repair. A supplemental fastener repair can
vary from adding supplemental fasteners at
top floor corner zones (where design wind
pressures will be the highest) to supplemental
fasteners at every floor at a certain
horizontal spacing. Some expert witnesses
believe that if the siding has been attached
in a blind nail condition, one should not
add supplemental fasteners because manufacturers
do not allow “double” nailing;
however, this is not true. Manufacturers
will allow a blind nail/face nail condition for
repairs in high-wind coastal areas.
Complete removal and replacement of
the fiber cement board siding based on
inadequate as-built attachment are rarely
justified. Typically, if complete removal
and replacement are recommended, it is
because of other construction issues (i.e.,
moisture intrusion, structural conditions)
that need to be addressed.
2 9 t h RC I I n t e r n a t i o n a l C o n v e n t i o n a n d T r a d e S h ow • Ma rc h 2 0 – 2 5 , 2 0 1 4 H o d g i n a n d Wy l i e • 3 3
CON CLUSION S
As described above, the installation of
fiber cement board siding includes many
variables that affect the adequacy of the
attachment to resist code-defined loads.
Each of these variables must be considered
to determine if the installation is defective
and if a repair is needed. It is not reasonable
to assert that the siding installation is
defective simply because the as-built conditions
deviate from the published manufacturer
literature. To serve as an engineering
expert often requires performance of an
engineering analysis to support opinions to
a reasonable degree of certainty. Offering
opinions without valid support diminishes
our roles as experts and compromises the
integrity of our profession.
REFERENCES
1. James Hardie Building Products,
Technical Bulletin #17 – Fastening
Tips for HardiePlank® Lap Siding,
March 2012
2. International Residential Code for
One- and Two-Family Dwellings
(IRC), 2003
3. International Residential Code for
One- and Two-Family Dwellings
(IRC), 2006
4. International Residential Code for
One- and Two-Family Dwellings
(IRC), 2009
5. International Residential Code for
One- and Two-Family Dwellings
(IRC), 2012
6. ASTM International, F1667-11a:
Standard Specification for Driven
Fasteners: Nails, Spikes and Staples,
March 2012
7. Journal of Light Construction,
JLC Field Guide for Residential
Construction
8. FEMA P-499, Home Builder’s Guide
to Coastal Construction – Technical
Fact Sheet Series, December 2010
9. CertainTeed WeatherBoards™, Fiber
Cement Board Siding – Installation
Manual, June 2012
10. James Hardie Building Products,
Hardieplank HZ10 Lap Siding
Installation Requirements, November
2012
11. NichiBoard™, NichiProducts – Installation
Guidelines, May 2012
12. James Hardie Building Products,
Technical Bulletin #5 – James Hardie
Fastening Requirements: Alternate
Fasteners, June 2012
13. American Forest & Paper Association
and American Wood Council, National
Design Standard for Wood
Construction, 2005 Edition
14. APA, Technical Topics: TT-039C –
Recommended Design Values for Nail
Withdrawal From APA Plywood and
OSB, July 2010
3 4 • Ho d g i n a n d Wy l i e 2 9 t h RC I I n t e r n a t i o n a l C o n v e n t i o n a n d T r a d e S h ow • Ma rc h 2 0 – 2 5 , 2 0 1 4
As previously stated, to serve as an engineering expert often
requires that an engineering analysis be performed to support
opinions to a reason degree of certainty. To simply assert that the
siding attachment is defective because the as-built conditions deviate
from applicable building code and/or manufacturer literature
is not reasonable. The following hypothetical example demonstrates
how to correctly evaluate and analyze as-built siding conditions, in
addition to formulating a reasonable recommended repair.
Building Information
The subject building is a three-story residential building in
Charleston, South Carolina. At the time of original construction,
the applicable building code was the 2006 IRC. The subject building
is located in an Exposure C. The engineering analysis will be
performed at a height of 30 feet (at the third floor). The following
data were collected during a visual survey:
• Siding was face-nailed with one fastener per location.
• Average horizontal spacing was measured at 18 in. oncenter.
• Vertical spacing was measured to be 7 in. on-center.
• The wood framing was No. 2 southern yellow pine.
• The wall sheathing was OSB and was measured to have a
thickness of 7/16 in.
• Two of the observed eight fasteners were installed into the
wood framing.
• The fastener was observed to have the following properties:
— Smooth-shank nail (common nail)
— Shank diameter of 0.131 in.
— Length of 2 in.
• The siding was measured to have a thickness of 5/16 in.
Design Wind Pressure Analysis
The code-defined design wind pressures at the subject building
can be determined by the 2006 IRC. Specifically, by determining
the basic wind speed from the wind speed maps, the velocity wind
pressures can be determined for the corner zone (i.e., Zone 5) and
the interior zone (i.e., Zone 4). The velocity wind pressures are then
adjusted by a height and exposure coefficient to determine the
design wind pressure. Table 2 shows the code-defined wind pressure
analysis.
Fastener Withdrawal Analysis
Determining fastener withdrawal is based on the code-referenced
industry standard, the “National Design Specification for
Wood Construction” (NDS). Fastener withdrawal resistance is based
on a mathematical equation that takes into account several factors
that may affect the attachment when subjected to different types
of loads, environmental conditions, fastener type, and construction
conditions. A key factor in determining the fastener withdrawal
resistance is determining the depth of penetration of the fastener
into the wood stud framing and OSB wall sheathing.
Table 3 shows the NDS withdrawal design values for both the
wood stud framing and the OSB wall sheathing. Additionally, Table
3 shows the adjustment factors that are applied to determine the
design withdrawal value for both the wood stud framing and OSB
wall sheathing.
As-Built Attachment Conditions vs. Code-Defined Wind Loads
When the design wind pressure calculations and fastener
withdrawal resistance calculations have been performed, the asbuilt
attachment conditions can be compared to the code-defined
loads. The vertical and horizontal spacing of the fastener are used
to determine the tributary area of a fastener. The effective area is
needed to convert the design wind pressures to fastener withdrawal
requirements.
From the data collected, some of the fasteners did not penetrate
the wood stud framing. Therefore, the withdrawal resistance for the
OSB wall sheathing and wall stud framing/OSB wall sheathing is
compared with the code-described wind loads. Table 4 shows the
conversion from a design wind pressure to a design wind load.
Additionally, Table 4 shows the comparison of fastener withdrawal
resistance to design wind loads for both conditions (i.e., OSB wall
sheathing and wood stud framing/OSB wall sheathing).
2 9 t h RC I I n t e r n a t i o n a l C o n v e n t i o n a n d T r a d e S h ow • Ma rc h 2 0 – 2 5 , 2 0 1 4 H o d g i n a n d Wy l i e • 3 5
Table 2 – Code-defined wind pressure analysis.
APPENDIX: SIDING ATTACHMENT EXAMPLE
Recommended Repair
The engineering analysis revealed that the as-built attachment
conditions are insufficient to resist code-prescribed wind loads at
some locations. Specifically, a fastener that penetrated both the
wood stud framing and OSB wall sheathing is adequate to resist
code-defined wind loads. However, a fastener that penetrated just
the OSB wall sheathing is not adequate to resist code-defined
wind loads in both Zone 4 and Zone 5. Based on the engineering
analysis, the authors would recommend installing supplemental
fasteners at a specific on-center spacing (to be calculated) to
resist the code-defined wind loads. Additionally, the supplemental
fasteners would have to be installed in accordance with the
manufacturer’s literature.
3 6 • Ho d g i n a n d Wy l i e 2 9 t h RC I I n t e r n a t i o n a l C o n v e n t i o n a n d T r a d e S h ow • Ma rc h 2 0 – 2 5 , 2 0 1 4
Table 3 – Withdrawal analysis (wood framing and sheathing).
Table 4 – Withdrawal resistance vs. code-defined wind load.