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StuccoMetrics® |
Jeff Bowlsby CCS, CCCA
Exterior Wall and Stucco Consultant
Licensed
California Architect
Minimum Stucco Industry Standards
and Other Reference Resources
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Webpage Outline Codified
Resources: Minimum Stucco Industry
Standards Model Building Code Requirements,
Approved Alternates, Regional Requirements and Regional Practices Non-Codified
Resources: Other Stucco Industry
Reference Resources Myths Regarding Stucco Industry Standards and
Other Reference Resources |
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Minimum Stucco Industry
Standards requirements are the minimum requirements for stucco design,
materials and installation. To satisfy
Minimum Stucco Standards of Care, design professionals are required to design
and construction professionals to build in compliance with the Minimum Stucco
Industry Standards, or to exceed them.
Stucco Best Practices exceed Minimum Stucco Industry Standards requirements. Minimum Stucco Industry Standards are peer
reviewed, stated in mandatory language, and adopted and enforceable by an
authority having jurisdiction (AHJ).
In conformance with those parameters, the only Minimum Stucco Industry
Standards are the locally-adopted building code and its internal reference
standards. Also
circulating within the stucco industry is a significant volume of other
reference resources that are not Minimum Stucco Industry Standards, but may be
promoted, referred to, or perceived and misinterpreted as such. Numerous trade and manufacturer
organizations and individuals circulate generally helpful advisory books,
journal articles, technical bulletins, newsletters, manuals, guidelines,
suggestions, recommendations and an abundance of other written information
about stucco. Use wisdom and
discernment in recognizing that other non-building code reference resources
are opinions only and therefore discretionary and non-mandatory. Although not developed by consensus-based
organizations, most of the information in these other stucco reference
resources is of generally good quality and beneficial to stucco in some way
by promoting the use of better quality materials, detailing, and practices
which may exceed Minimum Stucco Industry Standard requirements and a Minimum
Stucco Standards of Care. Additionally, some of these
other resources may be significant from a historical perspective as an
insight into the development and status of stucco in previous eras, but which
have been superseded by more current information or requirements and although
informative, are obsolete today. Unfortunately, some of the information
from certain stucco reference resources merely promote unsubstantiated
opinions, speculations, unproven materials or methods, may be based on
incomplete or inaccurate information, may contain factual inaccuracies or may
conflict with the building code or are unproven discretionary practices or
materials. These circumstances can and
do contribute to conflicts on today’s jobsites, misinterpretations of
contract documents, misinformation, misunderstandings, potentially defective
construction and ultimately less than satisfactory stucco. It is incumbent upon the individual design
and construction professional to have a clear understanding of legitimate
Minimum Stucco Industry Standards requirements and to discern the differences
with other stucco industry resources, and it is essential to consider the
source of information as important criteria when evaluating each stucco
reference resource or information. Visit the StuccoMetrics Reference Archives
webpage for cited references and further information. |
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The earliest efforts at developing
Minimum Stucco Industry Standards to establish minimum stucco quality
resulted from the collaborative efforts of the US Commerce Department Bureau
of Standards, product manufacturers, design and engineering professionals and
stucco craftsmen. That basic model is
still practiced today, but the process is largely privatized. The historical documents that follow are
among the more significant milestone documents developed in earlier years
that are the foundation of our Minimum Stucco Industry Standards today: ·
1911
Bureau of Standards testing as reported in the 1917 Annual Report ·
1914
Bureau of Standards Technologic Paper No. 43, Hydration of Portland Cement,
Klein ·
1917
Bureau of Standards Technologic Paper No. 70, Durability of Stucco, Wig,
Pearson, Emley ·
1918
American Concrete Institute (ACI) Proceedings Fourteenth Annual Convention,
Tests of Stucco, Pearson ·
1920
American Concrete Institute (ACI) Standard No. 25 – Standard Recommended
Practice for Portland Cement Stucco ·
1926
Bureau of Standards Circular No. 311 Stucco Testing, Hitchcock ·
1929
Portland Cement Association (PCA) Plasterer’s Manual ·
1946
American Standards Association (ASA) A42.2
Standard Specifications for Portland Cement Stucco ·
1946
American Standards Association (ASA) A42.3
Standard Specifications for Portland Cement Plastering including
Requirements for Lathing and Furring ·
1964
American Concrete Institute (ACI) 524 Guide to Portland Cement Plastering ·
1971
American National Standards Institute (ANSI) A42.2-1971 Portland Cement and Portland Cement-Lime
Plastering, Exterior (Stucco) and Interior ·
1971
American National Standards Institute (ANSI) A42.3-1971 Lathing and Furring for Portland Cement and
Portland Cement-Lime Plastering, Exterior (Stucco) and Interior ·
1981
American Society for Testing and Materials (ASTM) C926 Application of Portland Cement-Based
Plaster ·
1986
American Society for Testing and Materials (ASTM) C1063 Standard Specification for Installation of
Lathing and Furring for Portland Cement-Based Plaster ·
2006
International Building Code (IBC)
…And more…. Historically, the stucco industry has
been strongly influenced by the craftsman trades. This has been beneficial in many ways for
stucco because stucco requires skilled labor, hand-fabrication, and
site-installation with a wide range of variables that the stucco installer
must consider and adapt to for each stucco installation. Minimum Stucco Industry Standards promote
the common ground of proven minimum practices and provide craftsman
reasonable latitude, within defined limits, to make subtle jobsite
refinements facilitating a stucco installation to accommodate site specific
environmental conditions that benefit the stucco installation process and
installed stucco performance. |
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Stucco
materials, design practices and installation procedures have developed
through the collaborative efforts from every corner of the stucco industry. |
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In recent decades, advances in technical
and aesthetic considerations in architectural design, owner sophistication
and expectations, stucco industry technology and in the wall assembly
delivery process have resulted in a level of sophistication and complexity
impacting stucco not previously experienced in the marketplace. This has resulted from the impacts to the
stucco industry on the constantly developing process of accommodating new
materials, increased owner and architect expectations for design and quality,
performance, schedule, and reduced cost, building code developments,
inspection requirements, craftsman training and the residual effects of
litigation. Designing, installing and
coordinating a stucco cladding assembly in the context of contemporary
architecture and the current construction delivery environment with its
myriad of adjacent assemblies – windows/doors, WRB’s and drainage planes,
rainscreens, continuous insulation, fire testing and fire-ratings,
substrates, detailing requirements, and more – requires a very high level of
technical design and installation sophistication, forethought, collaboration
and coordination to be successful.
Minimum Stucco Industry Standards are a primary common basis and
define the minimum requirements that each of these different factors rely
upon. Minimum Stucco Industry Standards and
other reference resources are generally described and categorized below. A more complete listing of sponsoring
organizations and other reference resources is indicated on the StuccoMetrics
Reference Archives webpage on this website. Codified
Resources: Minimum Stucco Industry Standards
Building Code – Most USA states,
counties and cities, authorities having jurisdiction (AHJ) adopt a building
code which defines minimum construction requirements for a particular locale. Since the 1920’s the building codes have
been prescriptive codes, spelling out in detail, minimum stucco
requirements. The building code has
relied on reference standards to a limited extent for many years and has
developed in more recent years to become fundamentally dependent on
referenced standards, by adopting and incorporating reference standards into
the code, which are the subject of a continual development and consensus
review process by industry leaders.
Most USA authorities having jurisdiction today adopt the current
edition of the International Building Code, updated tri-annually and
sometimes with local amendments. Beginning with the adoption and local
enforcement of the 2000 International Building Code (IBC), select ASTM
Standard Specifications (1st tier reference standards) regarding stucco materials, design and
installation have been
incorporated by specific reference within the building code, are therefore legally binding and
enforceable Minimum Stucco Industry Standards. Before this time these standards and their
predecessors were developed as industry reference documents and were only
binding on a stucco installation if specified as a contractual requirement
for a project by the architect. Be
informed that like building codes, ASTM Standard Specification stucco
standards do not promote or even identify Stucco Best Practices, best quality
materials or workmanship, or assure that a minimally conforming stucco
installation will meet the aesthetic, performance and durability expectations
of a discerning building owner, architect or other evaluator. Compliance with these minimum requirements
will achieve a stucco assembly design and installation that meets Minimum
Stucco Industry Standards and probably nothing more. Note that the reference ASTM Standard
Specifications have additional internal references to other ASTM Standards (2nd
tier reference standards), which are also requirements for stucco. Interested stucco industry professionals –
manufacturers, architects, craftsmen - are encouraged to join and participate
in ASTM standards development, you will learn a lot, gain an appreciation of
your industry colleagues’ perspectives, and your participation and
contributions are valued. Currently,
the ASTM Standard Specifications (1st tier reference standards) specifically referenced in the IBC
building code include: ·
ASTM
C79 Standard Specification for Treated Core and Nontreated Core Gypsum
Sheathing Board [Withdrawn in 2004, superseded by C1396] ·
ASTM
C91 Standard Specification for Masonry Cement ·
ASTM
C150 Standard Specification for Portland Cement ·
ASTM
C595 Standard Specification for Blended Hydraulic Cements ·
ASTM
C847 Standard Specification for Metal Lath ·
ASTM
C897 Standard Specification for Aggregate for Job-Mixed Portland
Cement-Based Plasters ·
ASTM
C926 Standard Specification for Application of Portland Cement-Based
Plaster ·
ASTM
C932 Standard Specification for Surface-Applied Bonding Compounds for
Exterior Plastering ·
ASTM
C933 Standard Specification for Welded Wire Lath ·
ASTM
C954 Standard Specification for Steel Drill Screws for the Application of
Gypsum Panel Products or Metal Plaster Bases to Steel Studs from 0.033 in
(0.84mm) to 0.112 in. (2.84 mm) in Thickness ·
ASTM
C955 Standard Specification for Installation of Load-Bearing (Transverse
and Axial) Steel Studs, Runners
(Tracks) and Bracing or Bridging for Screw Application of Gypsum Panel
Products and Metal Plaster Bases ·
ASTM
C1002 Standard Specification for Steel Self-Piercing Tapping Screws for the
Application of Gypsum Panel Products or Metal Plaster Bases to Wood Studs or
Steel Studs ·
ASTM
C1007 Standard Specification for Installation of Load-Bearing (Transverse
and Axial) Steel Studs and Related
Accessories ·
ASTM
C1032 Standard Specification for Woven Wire Plaster Base ·
ASTM
C1063 Standard Specification for Installation of Lathing and Furring to
Receive Interior and Exterior Portland Cement-Based Plaster ·
ASTM
C1280 Standard Specification for Application of Gypsum Sheathing ·
ASTM
C1328 Standard Specification for Plastic (Stucco) Cement ·
ASTM
C1396 Standard Specification of Gypsum Board [This is the replacement
standard for C79, but it is not listed in code] Res
ips loquitur, referenced ASTM Standards speak for
themselves. Some of the multi-faceted
topics on StuccoMetrics.com require
comprehensive knowledge and careful evaluation of the specific ASTM Standard
text, which are not reproduced here in respect of copyrights. Readers are encouraged to purchase the
referenced ASTM Standards directly from ASTM and review them. Various editions of archived, “building
code-adopted” (codified) and “most current” versions of ASTM Standards are
available so be sure to obtain the version(s) needed. The referenced ASTM Standards and texts are
indicated for reader’s convenience, for purposes of topical discussion. Requirements
of the Standards are paraphrased, written in the imperative mood and
streamlined writing format as is recommended by the Construction
Specifications Institute (CSI) and common to construction specifications,
using the terminology developed and described on StuccoMetrics.com. Model Building Code Requirements,
Approved Alternates, Regional Requirements and Regional Practices Model building codes: Designed to serve broad sectors of the
construction community, model building codes have been useful to communities
throughout the USA and globally. Local
adoption of the same model codes by jurisdictions throughout the land has
provided uniformity to minimum stucco requirements, tremendous efficiencies,
benefits and conveniences to the stucco community. However, model codes have no effect unless
they are adopted by a state or local jurisdiction, which then becomes the
authority having jurisdiction (AHJ), which is the entity responsible for the
adopted codes’ enforcement. Recognize
that model building codes describe minimum requirements for stucco only, not
Stucco Best Practices, and become applicable to each jurisdiction only where they
are adopted. Approved Alternates: The AHJ may evaluate and potentially accept
alternates of stucco materials, designs, tests or methods of construction not
specifically prescribed in the code, but their evaluation of alternates is
conditional to the specific project only, and may require substantiation
based on evidence or testing. Evidence
may be required to substantiate claims that the proposed alternate conforms
to or is at least an acceptable equivalent to the performance, safety and
protection of life and health to the standards contained in minimum model
code requirements. Testing, when
required, must be performed by approved testing entities. Regional requirements: Before adoption, model building codes are
subject to the review and revisions of the AHJ to accommodate local conditions. The AHJ may establish more restrictive
requirements based only on local climatic, geological or topographical
conditions, but not less restrictive.
Local revisions to the model codes must be formally processed, adopted
and published within the local code, to be in effect. It is rare for an AHJ to make the required
findings necessary to adopt more restrictive regional requirements for stucco
than are contained in the model codes, but it does occasionally occur. As one example of a regional requirement,
in parts of the Northwest USA certain specific jurisdictions require enhanced
drainage provisions in stucco assemblies, due to the high levels of rainfall
in their climates, and have revised their local minimum code requirements
accordingly. This additional minimum
requirement is justified and derived from local climatic conditions and only
applies to the jurisdictions where it is adopted and enforced. Regional practices: The term “regional practices” describes
local variations from the minimum model code requirements, a term which
connotes an alternative method, technique, material or assembly that is
preferred or practiced locally, whether or not literally conforming to
minimum code requirements. Regional practices
may be difficult to evaluate for compliance with Minimum Stucco Industry
Standards which can require the highest levels of discernment. Regional practices regarding stucco design,
materials and installations present significant challenges to local stucco
practitioners, to inspectors of the AHJ, to design professionals, to ASTM and
to model code bodies because they are not embodied in the code or reference
standards. Examples of regional
practices not in compliance with the building code include items such
as: Omission of SMJS subassemblies,
placing the weep screed flange between the two layers of WRB, weep screeds
located less than 2 inches above paving, continuous lath at SMJS
subassemblies and more. These and
other conditions must sometimes be adjudicated to determine acceptability –
which is avoidable if literal codes are followed. Non-Codified
Resources: Other Stucco Industry
Reference Resources Notwithstanding the importance of
Minimum Stucco Industry Standards as expressed in building code requirements,
the design professional has the liberty to specify, for purposes of a
contractual requirement on a specific project, any other stucco industry
reference resource, stucco component, assembly or practice, as long as it
meets or exceeds and does not conflict with the building code or Minimum
Stucco Industry Standards requirements.
Other stucco industry reference resources specified in this way become
contractually enforceable requirements for a specific project. Non-building code stucco industry resources
that have been around for a while may be outdated, may be in conflict with
current Minimum Stucco Industry Standards, or be irrelevant to a specific
project. A caution is that we must be cognizant as design and construction
professionals, of the potential for conflicts between other non-codified
reference resources and the building code and use the highest professional
discretion when using, specifying and referencing non-codified stucco
reference resources which are not adopted by an authority having
jurisdiction. Some of the non-codified
stucco reference resources have morsels of wisdom which may be considered
Stucco Best Practices…whereas in the same resource flawed information may be
presented. Only professional
discretion and being fully-informed can assist in separating fact from
fiction. A well-intentioned but
uninformed, indiscriminate broadly-worded specification or reference to a
non-building code stucco industry reference resource may result in a less
than minimally acceptable stucco installation or performance. If the content of everything in a given
non-building code stucco industry reference resource is not fully known or
understood, then it may be below the Minimum Stucco Standard of Care to
broadly specify it as a reference resource in contract documents, or to
follow its practices in construction.
Select portions of other stucco industry reference resources may be
specified effectively for the purpose of improving stucco beyond Minimum
Stucco Industry Standards requirements if the selective reference information
is limited in scope, clearly defined and does not conflict with Minimum
Stucco Industry Standards requirements. ASTM Standard Guides and Standard
Practices The American Society for Testing and
Materials brings together industry professionals representing varied
interests in stucco to collaborate and develop publications of material,
installation and testing Standard Specifications, Standard Guides and
Standard Practices that are subject to a rigorous consensus review process
and continuous development that are mutually agreeable amongst participants. Select ASTM Standard Practice and Standard
Guide standards for stucco are not codified, but offer excellent
supplementary stucco design, installation and testing information that may be
referenced in specifications including: ·
ASTM
C1193 Standard Guide for Use of Joint Sealants ·
ASTM
E2112 Standard Practice for Installation of Exterior Windows, Doors and
Skylights ·
ASTM
E2128 Standard Guide for Evaluating Water Leakage of Building Walls ·
ASTM
E2266 Standard Guide for Design and Construction of Low-Rise Frame Building
Wall Systems to Resist Water Intrusion Design
Professional/Consultant/Research-Based Stucco Resources BSC Building Science
Corporation ·
Technical
stucco research papers CMHC Canadian Mortgage
and Housing Corporation ·
Technical
stucco research papers CSI Construction Specifications
Institute ·
Technical
stucco articles and guide specifications RCI Roof Consultants
Institute ·
Technical
stucco research papers StuccoMetrics.com ·
Stucco
design and technical resources from the perspective of an architect and
professional stucco consultant. Stucco
Product Manufacturer Organization-Based Resources Stucco product manufacturer-based
organizations are best positioned to know and promote the objective
capabilities, limitations and installation requirements of their industries’
products and materials. Stucco product
manufacturers produce generic and proprietary materials and components for
stucco assemblies including complete stucco assemblies. Installation requirements for materials and
components that are generic are generally described in the building code and
its reference standards. Where
requirements for a proprietary stucco product or component are not adequately
addressed in the code, it is incumbent upon manufacturers to provide the
necessary information to use and install their products effectively and many
of these resources are objective and excellent. Standard practice in all construction
disciplines including stucco and the minimum standard of care for design and
construction professionals is to follow product manufacturers written
requirements for their products. Manufacturers of proprietary stucco
components and systems, that are approved alternatives to the generic
requirements in the building code provide proprietary installation
requirements specific to their products in the form of code evaluation
reports and installation information that must be followed explicitly for the
installation to be building code compliant.
ACI
American Concrete Institute As the oldest American industry
organization concerning portland cement, the predecessor to what is now ACI
was established in 1905. ACI’s focus
is “to develop, share, and disseminate the
knowledge and information needed to utilize concrete to its fullest potential”. ACI has existed for over a century and
while its primary emphasis is on portland cement concrete, ACI also developed
the first portland cement stucco reference resource in 1920, Standard Recommended Practice for Portland
Cement Stucco, Standard No. 25, followed in 1964 by ACI 524 Guide to Portland Cement Plastering. Many of the practices from these early
documents also included in the current documents are relevant today because
the essential characteristics of portland cement have not changed all that
much. ·
ACI
524R Guide to Portland Cement-Based Plaster APA American Plywood Association Plywood and other structural wood panels perform an important
function related to stucco wall cladding systems. ·
TB202
Use of Structural Panels In Stucco And EIFS Wall Systems ·
Q370G
Installation Of Stucco Exterior Finish Over Wood Structural Panel Wall
Sheathing EMLA Expanded Metal Lath Association EMLA is the manufacturer-based trade organization for metal lath
and lath accessories and its
predecessors have been around for decades disseminating information for using
metal lath with stucco. EMLA is one of
several manufacturer associations under the NAAMM organizational umbrella. ·
EMLA
920 Guide Specifications for Metal Lathing and
Furring FCPA Florida Concrete and Products
Association Primarily in the Southeast USA region,
stucco is directly applied to concrete, CMU and masonry substrates as a
barrier wall cladding. ·
Various
stucco technical bulletins PCA
Portland Cement Association For
all things related to portland cement, the Portland Cement Association,
established in 1916 plays an integral role. ·
EB049 Portland
Cement Plaster/Stucco Manual SBA Structural Board Association While no longer active, from 1976-2008 the
SBA primarily represented the oriented strand board OSB industry. Structural wood panels perform an important
function related to stucco wall cladding systems. ·
TB112
Good Stucco Application Practices SMA Stucco Manufacturers Association
The SMA mainly functions to promote the use of traditional 3-coat
stucco and its products. Its
membership represents a cross-section of mostly stucco product manufacturers
including cementitous materials, lath and lath accessories, and polymer-based
finishes. ·
Various
stucco technical bulletins Stucco
Contractor Association-Based Resources AKA Stucco Bureaus: In the late 1920’s, the first lathing
and plastering trade association in America was formed in Southern California
in one of the strongest regional stucco markets even today. Stucco bureaus in other regions large and
small have multiplied across the USA since that time. These organizations began as and are today,
organized labor and trade promotion associations – i.e. representing the
interests of unionized lathing and plastering contractors. They have evolved to include regulatory and
technical assistance components to promote the stucco industry, and to assist
their membership and select others with regulatory and technical issues from
the craftsman’s perspective. Stucco
bureaus develop, publish and distribute various written reference resources
on stucco, a significant portion of which is of good quality and complies
with the building code and Minimum Stucco Industry Standards. Individual
Authors – Books, Manuals and Articles
in Professional and Trade Journals Numerous publications from books,
symposium proceedings, to periodicals address various stucco topics. The quality of these publications ranges
from excellent to Stucco Best Practices to marginal to below Minimum Stucco
Standards of Care, and readers’ discretion is suggested. Myths Regarding Stucco Industry Standards and Other Reference
Resources Stucco myths are dichotomous,
masquerading as universal truth in spite of their untruths. Just because they are spoken does not make
them true. These myths circulate and
rear their ugly heads from time to time: Stucco
Myth - “Stucco is an art, it has no absolutes”.
This phrase is misused in an attempt to justify designer, installer or
inspector mistakes, preferences or oversights. Stucco does have artistic components which
are non-absolutes, but in the same breath it does have technical absolutes,
hence the dichotomy. The creative and
aesthetic choices and craftsmanship involved in creating a texture, or in
selecting the correct color – is an artful expression and the acceptability
and variability of the results may require interpretation and discretion and
possible rework. The technical aspects
of stucco however require technical knowledge, skill and experience but do
not require Michelangelo to get right.
The specification of appropriate components, the execution of correct
installation techniques, the inspection of each installed component in a
stucco wall cladding system are all left-brain tasks that are not ‘art’, and
are either right or wrong. So where
portland cement finish coats in dark integral colors are specified as a
creative decision, one should also be prepared to accept or mitigate the
potential technical condition of efflorescence, it’s a technical issue –
those white splotches are not ‘patina’ and not art. Stucco
Myth – “The term ‘stucco industry standard’
includes a wide range of documents and practices, as published by ASTM and
major stucco trade organizations like AWCI, ACI, and stucco bureaus and
common local practices performed over time”. The term ‘industry standard’ is highly
misused, misunderstood, mischaracterized and misapplied within the context of
stucco. Let’s be clear, a Minimum
Stucco Industry Standard does not include every stucco industry reference
resource ever written or every lath accessory installation technique ever
employed, no matter how long you have been doing it that way. Many reference resources are merely
opinions whether produced by organizations or individuals and do not carry
the authority garnered by an industry consensus review process, or
enforceability of a codified Minimum Stucco Industry Standard. The word standard means “something
considered by an authority or by general consent as a basis of comparison; an
approved model. A rule or principle
that is used as a basis for judgment.”
(Dictionary.com). Minimum Stucco Industry Standards must have binding legal
authority and only include the building code in effect for a given
jurisdiction, including any reference standards within the building code such
as ASTM standards. Other stucco
industry reference resources may have excellent information in many but not
all respects, however they are not subject to the purview of an adopting and
enforcing authority and are therefore not Minimum Stucco Industry Standards,
they are only informational, opinion-based resources unless they become a
specified requirement in a projects contract documents, and do not conflict
with Minimum Stucco Industry Standards.
So when it is suggested as examples, that information published in a
stucco article published by a notable person in the industry is an ‘industry
standard’, or where inserting the weep screed flange between the two layers
of water-resistive barrier is an ‘industry standard’, where these conditions
are in conflict with Minimum Stucco Industry Standards, you can discern that
these are not true statements. Stucco
Myth – “Installation methods prescribed in ASTM Standards are good national
guidelines, but local and regional practices are just as good and take
precedence, because this is the way we do stucco around here”.
The part of this statement that is true is that certain regional
stucco practices may provide effective, code compliant alternative methods to
satisfying a requirement or may be at the preference or discretion of the
installer where there is no regulation.
These situations might include things such as using local sand that
has a proven performance record, or for selecting one code-recognized lath
type over another. Regional practices
may be acceptable if they result in code compliance, but the local building official
is the only entity with authority to evaluate and accept alternative
solutions to minimum code requirements, although he is under no obligation to
do so, and even then, only under specific circumstances, where they are based
on acceptable testing performed by accredited entities. The myth part of the statement is that some interests in the stucco
industry follow the misguided notion that ASTM Minimum Stucco Industry
Standards are mere ‘guidelines’ and that the skill of the installer and an
undefined and constantly changing set of interpretive ‘regional practices’
dictate what should really be followed.
With that perspective, stucco wall cladding systems cannot be
consistently designed or constructed in a manner to expect repeatable
successful performance and cannot be reasonably evaluated to avoid repeating
mistakes. Actual bona fide minimum stucco
requirements then become diluted and blurred.
Attempts, intentional or otherwise, to justify stucco work or
practices that in some way conflict with building code requirements or ASTM
Minimum Stucco Industry Standards on the basis of ‘regional practice’ are
misguided and without justification.
To suggest that this may be acceptable is beneath the Minimum Stucco
Standard of Care for licensed design and construction professionals that are
obligated to uphold the minimum building code as the Minimum Stucco Industry
Standard of Care. ASTM Minimum Stucco
Industry Standards are not just national ‘guidelines’ that may apply
somewhere else, they are minimum requirements for anything related to stucco
on a building anywhere the Minimum Stucco Industry Standards are adopted by
the building code. The building code
is the minimum building construction standard stated in mandatory language,
and every requirement of the standards referenced in the building codes are
legally binding requirements for stucco.
So for example, one should reconsider when contemplating assembling
BMJS or SMJS subassemblies or foregoing moist curing in ways that differ from
what ASTM C1063 or ASTM C926 requires to assure that the stucco work complies
at least with the minimum requirements embodied within Minimum Stucco
Industry Standards. |
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Knowledge
of Minimum Stucco Industry Standards is critical to complying with the
Minimum Stucco Standard of Care.
Having the discernment to know the distinction and applicability
between the Minimum Stucco Industry Standards and other stucco industry
reference resources is foundational in the process of satisfactorily
designing, constructing and inspecting stucco that meets minimal, reasonable
expectations. |
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Minimum
Stucco Standards of Care: ·
Design,
specify and construct stucco in conformance with the locally adopted building
code and its internal reference standards.
These are the only Minimum Stucco Industry Standards for stucco. Specify no other references unless specified
selectively, to avoid potential conflicts with the Minimum Stucco Industry Standards. ·
Avoid
broadly specifying or referencing other non-building code stucco industry
reference resources without a thorough knowledge of their entire contents to
avoid the potential for unintentional conflicts with Minimum Stucco Industry
Standards. Stucco
Best Practices: ·
Design
and stucco industry professionals are encouraged to design, specify and
construct stucco complying with Stucco Best Practices that exceed the Minimum
Stucco Industry Standards requirements in the building code and its internal
reference standards to achieve higher quality and better performing stucco. ·
Use
professional discretion when using local and regional practices and comply with the minimum
requirements of Minimum Stucco Industry Standards. Verify that local or regional practices do
not conflict with Minimum Stucco Industry Standards requirements. ·
Many
non-codified stucco industry reference resources offer generally good-quality
stucco information because they generally represent the best interests of the
stucco materials or installation practices involved, but review them
carefully for conflicts with Minimum Stucco Industry Standards before
specifying or following their recommendations. ·
Specify
that the stucco work comply with building codes and ASTM Minimum Stucco
Industry Standards only. Avoid
specifying references to any other publications other than product
manufacturer publications, unless carefully coordinated with specific
projects requirements to avoid conflicts with Minimum Stucco Industry
Standards, conflicts that may be challenging to resolve during construction. ·
Sometimes
non-building code stucco industry reference resources offer improved
practices or methods, exceeding minimum requirements, or are desirable by the
specifier or craftsman for a specific project, without wanting to adopt the
entire reference. Carefully coordinate
selectively specifying project requirements from non-codified stucco industry
resources. ·
Carefully
review stucco related, non-codified ASTM Standard Guides and Standard
Practices resources and consider implementing their recommendations for use
with stucco clad exterior wall assemblies that are designed, constructed or
evaluated. The building construction industry that uses wood framing would
benefit from supplemental information for wood framing requirements where
portland cement-based plaster wall claddings are installed. Searches and consultations with others more
knowledgeable have identified nothing available regarding specific
conditions. Wood-framed buildings
constitute most residential and low rise construction in the USA, and the
lack of a resource like this is beyond unimaginable. What is available is the building code,
technical bulletins, wood products manuals and grading rules from wood
product producers and various organizations like APA, WWPA etc., and while
these are very helpful, a gap exists in how to use, install and fabricate
wood-based products to create building structures (the stucco substrate support system) as they
specifically pertain to stucco wall claddings. For example, the light gage steel frame
industry has ASTM C754 Standard Specification for
Installation of Steel Framing Members to Receive Screw-Attached Gypsum Panel
Products, and ASTM C1007 Standard Specification for Installation for
Load-Bearing (Transverse and Axial) Steel Studs and Related Accessories, and
the gypsum industry offers ASTM C1280 Application
Of Gypsum Sheathing, but the
wood products industry has nothing comparable available for framing or
sheathing system installation, which are stucco substrate supports and effect
the stucco performance. The current
void in information for wood-framing systems as they relate to portland
cement-based plaster include items such as: ·
Acceptable
planarity requirements (tolerances) of a wood framed wall. Bowed studs (crown in or crown out) and
transitions between sheathed and open-stud framing (steps or offsets) as a
stucco substrate support greatly influence the uniformity of thickness, or
rather the thickness variation of the stucco wall cladding, which affects the
planarity of the finished stucco surface and performance of the stucco
cladding as it relates to cracking. ·
Acceptable
conditions for installed structural framing accessories – framing clips,
straps, beam support buckets, lag screw heads, nail heads, etc, are typically installed over the face of framing or
sheathing, which create thickness variations in stucco, which affects the
planarity of the finished stucco surface and performance of the stucco
cladding as it relates to cracking. ·
Acceptable
methods to achieve or correct wood-framed planarity conditions to be
acceptable for stucco exterior wall claddings – acceptable shaving
limits? Shimming requirements? Recommended materials? ·
A
provision for required additional framing/blocking such as in ASTM C1007 Standard Specification for Installation of
Load Bearing (Transverse and Axial) Steel Studs and Related Accessories: “A2.4 Care shall be taken
to allow for additional studs at panel intersections, corners, doors, window,
control joints, etc.” whether or not specifically indicated on
construction contract drawings/details.
Blocking is routinely provided for towel bars and handrails, stucco lath
accessory substrate support requirements are equally as important. ·
Notched
sheathing panel requirements at wall opening corners preferably using a
router rather than overcuts with a saw, similar to ASTM C1280 for gypsum
sheathings. ·
Blocking
requirements for sheathing panel edges perpendicular to studs. ·
Current
requirements for oriented strand board and similar wood-based sheathings used
with stucco wall claddings, such as minimum panel thickness and WRB
permeability/impermeability requirements, if they are different than for
plywood. The Structural Board
Association has been defunct for many years without a replacement
organization. Either way the
requirements need to be defined and stated. ·
And
more… Additional stucco product manufacturer organization-based
resources would be beneficial to all with an interest in the stucco
industry. A current void of
information exists for needed resources including comprehensive technical
reference information specific to the unique qualities, characteristics,
performance and installation requirements of these materials for the
following: ·
Welded
wire/woven wire metallic lath and lath accessories ·
Non-metallic
lath and lath accessories ·
Lamina
base coats and polymer-based finish coats ·
Stucco-like
wall cladding systems used with tile and stone claddings ·
Stucco
wall cladding systems used with continuous insulation ·
Stucco
wall cladding systems used on low-slope weather-exposed conditions ·
Extruded
aluminum and extruded vinyl lath accessories ·
Lath
accessory shimming parameters ·
Water-resistive
barrier/air barrier and defined drainage wall systems ·
NFPA
285 assembly testing for all stucco wall cladding system combinations |
|
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stucco-related endeavors. No liability
is accepted for any reason or circumstance, specifically including personal
or professional negligence, consequential damages or third party claims,
based on any legal theory, from the use, misuse or reliance upon information
presented or in any way connected with StuccoMetrics.com. |
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