StuccoMetrics®

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Jeff Bowlsby CCS, CCCA

Exterior Wall and Stucco Consultant

Licensed California Architect

 

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Minimum Stucco Industry Standards

and Other Reference Resources

 

 

Webpage Outline

 

Executive Summary

Context

Observations

Discussion

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

Conclusions

Suggestions

 

Executive Summary

 

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.

 

Context

 

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

 

·                 1986 American Society for Testing and Materials (ASTM) C1063  Standard Specification for Installation of Lathing and Furring for Portland Cement-Based Plaster

 

·                 1986 American Society for Testing and Materials (ASTM) C926  Application of 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.

 

Observations

 

Stucco materials, design practices and installation procedures have developed through the collaborative efforts from every corner of the stucco industry.

 

Discussion

 

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.

 

Conclusions

 

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.

 

Suggestions

 

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

 

 

 

Consultation with licensed and experienced stucco professionals is recommended for 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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