Rosalind Fazel. Comments on Criteria AC51. Chris Hines Boral Stone Products

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1 Rosalind Fazel From: Sent: To: Subject: Monday, December 22, :58 AM Rosalind Fazel AC51 Comments Comments on Criteria AC51. Chris Hines Boral Stone Products Comments: 1. 1a. Drawings and evaluation of every stone unit would be an unnecessary burden. Measurement of a "texture" or "pattern" is sufficient. Material density X Specified Avg thickness confirms product is within the 15lbs/sqft limit. While some individual units might extend slightly beyond 2 5/8" thickness, the average remains closer to 1 5/8". 1b. Saturated density should not be used in AC-51 until building code requires such. No safety risk is added because product on the wall in actual use is never/rarely even close to saturated. 1c. Not needed until ASTM C1670 is referenced in the building code 1d. ASTM C15 Committee over Manufactured Masonry Units, has discussion/ballots underway to add more average thickness evaluation options. And even with those, will still leave the door open for a lab to propose their own method. 2. ASTM C1670 is not referenced in the code yet. The standard does raise the compliance requirements when compared to AC-51, and the industry will require some time to adjust/prepare/test. It is likely this standard will be proposed as a reference to TMS402/ACI530. Suggest that ICC ES not include these provisions in AC-51 until after the conversation has occurred in the appropriate TMS/ACI committees. 3. On the topic of installation. Code language regarding installation has been added to the I-codes over the last few cycles. However, these were small steps in preparation for the publishing of ASTM C1780. This standard practice for installation will also likely be proposed for reference to TMS402/ACI Since the energy codes are requiring more continuous insulation, we must include options for compliance in AC-51. 4a. Yes 4b. Yes 4c. No 1

2 I have reviewed the recently published summary of proposed changes for AC 51, Acceptance Criteria for Pre Cast Stone Veneer dated December 1, Here are my thoughts and comments: Item 1a: Both the IBC and IRC (referencing TMS 402/ACI530/ASCE5) as well as ASTM C refer to the weight of the veneer in terms of units whereas AC 51 uses the terminology: representative patterns. The ICC letter, dated December 1, 2014 states: it is our understanding that several different shapes and sizes of veneer units are packaged together to create a particular pattern over the surface of the supporting wall. I am certain and sure that the industry does not manufacture or package individual units with any specific or intended pattern in mind. The process widely used in the industry involves molds which have been produced using natural stone. These molds produce individual stone units. Yet, the concrete stones that are produced from these molds have no intention to any predetermined or designed pattern to be installed on the wall. The selection of stones which are applied on the wall is up to the discretion of the installer, completely. The manufacturer does not provide any stone installation schedule, schematic or instruction relating one stone to another. Stones are produced from the molds and the molds are introduced to the production line at random and the stones are removed from the molds and packaged at random. Such a process which would involve a particular pattern as described in the ICC letter would be onerous to the installer and unmanageable by the manufacturer. The installation process is not unlike a nature stone installation in which the stones are random in size, shape and color and must be installed by experienced installers who are aware of the process of stone selection based on color, size and shape. The MVMA Installation Guide discusses this random selection process as follows: Before installing AMSV, lay out a minimum of 25 square feet (2.3 m2) at the jobsite so there is a variety of sizes, shapes, and colors from which to choose. Mixing AMSV sizes, shapes, textures and color will allow for variety and contrast in the design to achieve the desirable finished project. Follow AMSV manufacturers recommendations regarding mixing of product to achieve desired results. As a consequence, the term representative pattern has no meaning. Therefore, a unit approach seems to be the only practical approach. If all stones are in compliance with weight per square foot, then any pattern of installation would also be in compliance. This means that in order to meet the current 15 pounds per square foot limit, any single stone unit would not be thicker than about 1.65 in average thickness (this values varies slightly from manufacturer to manufacturer since the density and absorption of the concrete varies somewhat). But, as a general rule, this is the target (1.65 ). (it is not my recommendation that this average thickness nor any average thickness be stipulated or required). However, the code currently stipulates a maximum thickness of any unit of 2 5/8 which is possible while simultaneously complying with the 1.65 average target. Both of these conditions are independent but completely reasonable and manufacturable. 2 5/8 Maximum Thickness: ASTM C currently states in paragraph 9.2.2: The average thickness of each unit shall be less than or equal to 2 5/8. TMS 402/ACI 530.1/ASCE 5 states: Adhered veneer units shall not exceed 2 5/8 in specified thickness... the term average is not included in this statement and it is my argument that this requirement did not intend the thickness requirement to be an average. As noted above, the typical concrete mix density and absorption dictates a maximum average thickness of about 1.65 in order to meet the 15 psf and compressive strength requirements. As stated above, the code language clearly stipulates a maximum thickness for any single point on the veneer stone. From another view, it would be hard to believe that the

3 code writers would not include an absolute maximum unit thickness as part of the dimensional requirements for stone veneer. I believe ASTM has interpreted this code requirement incorrectly and I believe the word average should be stricken from the document (C ). Furthermore, other dimensions such as length and area are listed in this same sentence of the code are clearly not intended to be averages. Therefore, I support the requirement that any unit have a maximum height of 2 5/8 as measured from the plane of the base or bond surface to any point farthest from and perpendicular to this plane of bond surface. This is consistent with my interpretation of the existing code and I completely manufacturable and will have minimum impact on any existing profile in the market today. I do not believe that the product in the market today will exhibit appreciable failure if the requirement for a 2 5/8 maximum thickness, absolute, is enforced. Item 1b. The following statements are excerpted from the code (ACI /ASCE 5-05/TMS ); Prescriptive requirements for adhered masonry veneer Unit sizes Adhered veneer units shall not exceed 25/8 in. (66.7 mm) in specified thickness, 36 in. (914 mm) in any face dimension, nor more than 5 ft2 (0.46 m2) in total face area, and shall not weigh more than 15 lb/ft2 (718 Pa). In my view, the UNIT weight of a fully saturated unit cannot exceed 15 pounds per square foot AND the maximum thickness for a UNIT is clearly stated at 2 5/8. There is no average or about or for most units contained in this language. Therefore, one can only conclude that each and every unit may not exceed 2 5/8 thickness. AC 51 has not been in alignment with the code language. ASTM C1650, which was written and supported in a long and thorough process involving members of the manufacturing industry as well as academics and other experts in the concrete industry, was published in This document supports the language of the IBC and IRC (TMS 402/ACI530.1/ASCE5). The ASTM C states in paragraph 8.3.2: The weight per square foot of the unit shall be determined by multiplying the saturated density of the unit by the average thickness, and shall not exceed 15 lbs/ft 2. The ICC document states: some patterns may have one or two with thickness greater than 2 5/8 or a saturated weight greater than 15 psf,.... So, if we use this interpretation, is there a limit to the number of stones and the maximum thickness permissible? Should we say at most, two units... or it is acceptable if some, but not all stones exceed 2 5/8 thickness? It is not suggested that the method of measuring average saturated weight be changed, but it is suggested that the criteria as prescribed in the code be consistent in the Acceptance Criteria. Currently, the code and AC 51 are not consistent in this regard. The code and ASTM C1670 are specific and clear; AC 51 is vague, loose and unclear. However, I am in favor of utilizing an AQL sampling plan (99% confidence limit) to derive a sample size based on the total population. The population can be molds, stone units or square footage of stone units. If an AQL based sample size is randomly selection from the total population of molds/units/sq footage, then the calculation of average stone thickness can be meaningful. Item 1d. It is agreed that there are different methods of determining average saturated weight. However, each acceptable method should be described and included in the Acceptance Criteria. ASTM C1670 now lists several methods. If AC 51 references those methods, all is good. Include one or more acceptable methods in AC 51.

4 Item 2a: Saturated Density it is stated incorrectly in the ICC letter of December 1 ( Potential Revisions ) that AC 51 requires the determination of the equilibrium density to determine saturate density. The current Version of AC 51 states the saturated density is determined by increasing the oven dry density by a factor equal to the absorption capacity of the concrete mix. There is no reference to equilibrium density. ASTM C1670 requires the determination of the saturated density by saturating a unit then measuring the weight of the unit and then measuring the weight of the unit while submerged in water. Since lightweight aggregates are difficult to saturate (unless aided by vacuum processing of the specimen) and since lightweight concrete is difficult (and time consuming) to dry to constant weight, too much error, time and energy (heat) are expended in obtaining the oven dry density and absorption values. It is clearly much more straightforward to saturate a unit (or piece thereof) and obtain two weights (normal and submerged). For these values, saturated density is calculated. Item 2c Compressive Strength: I cannot recall how the compressive criteria in ASTM C1670 was derived. However, concrete experts weighed in and debated this issue. At some point, two independent criteria were agreed upon: Five (5) specimens to be tested with 2100 psi, average and 1800 psi minimum for any single test. AC 51 requires a minimum of 1800 psi and a no single value to exceed by more than 10% from the average of 5 samples. It seems the 2100 psi average, 1800 psi minimum addresses the 10 max average deviation issue. So, let s go with 2100 and 1800 psi two stage criteria. However, I can agree to the 1800 psi as a 5 sample average. Item 2d: There is no known value or benefit to flexural and tensile strength of concrete used for ACMV production. After all, these stone units are NOT structural. The compressive strength requirement seems to address the minimum quality of the concrete. Item 2g: The requirement in ASTM C1670 for linear dry shrinkage have been debated this month at the ASTM meetings in New Orleans. It seems the requirement for linear dry shrinkage (lds) was included in the new standard because lds has always been included for other masonry units, especially CMU. However, it was argued that bonding stone veneer to a cementitious substrate has little in common with constructing a CMU wall. There has been no prior need for lds and there has been no adhered stone veneer installation failures that have directly related to lds. Actually, it was argued, limiting the movement of one element of the assembled adhered veneer wall system might increase the opportunity for shear stress at the bond. For example, if the stone has little opportunity to expand or shrink such that the rates of expansion and/or contraction might not match the movement of the bonding mortar and/or scratch coat. The mis movement of these stone relative to the backing might be cause for shear stresses to debond the stone. Item 2h: The manufacturability of a unit which is 5/8 thick is increased compared the same product that is only ¼ thick. One can expect excessive breakage during demolding and packaging with a unit that measured ¼ compared to 5/8. Therefore, the industry (Manufacturers, installers, customers) are served by a requirement of minimum thickness of 5/8. Item 3a: I agree completely that the current shear bond testing requirements found in TMS 602/ACI 530.1/ASCE6 is not applicable to this industry. Cement paste preparation of the substrate of stone unit is not performed in installation practice. Furthermore, testing using various substrates is problematic. Due to the size of the sample substrate (approximately 6 x 6 ) it is impossible to fasten lath to a plywood block in such a manner that the lath does not become the point of compressive force failure rather than the mortar to stone.

5 The purpose of the shear bond test is to evaluate the bondability of the back of the stone unit. A straightforward test employing randomly selected, representative stone units and a standard, fully cured mortar substrate is recommended. ASTM C482 is currently followed, with modifications. This method is recommended for ACMV. Item 3b: I support the recommendation provided in the ICC letter. Item 4: Installation over foam sheathing. Headwaters Stone Division has commissioned and published a Technical Evaluation Report which specifies fastener style and types for installation over thick foam. ered_masonry_veneer.pdf This report stipulates the fastener requirements for various wall substrates, various total façade weights per square foot and total spacing between the substrate and veneer. Since Headwaters Stone Division offers the market the widest selection of stone profiles, the weight per square foot of these various profiles varies significantly. Brick veneer, for example, might average ¾ thick per unit whereas another stone might average 1.5, per unit. The thickness difference translates to a significant total façade weight per square foot difference. A difference in fastener selection can be realized as a result of this weight difference. Therefore, a single value of 25 psf is overly restrictive. For example, with thick insulation projects (>2 ), the input of 25 psf might provide a solution which requires Z girts instead of screws to support the lath. The z girts are known to contribute significantly more thermal inefficiency compared to a screw. Consequently, this overly conservative approach results in a loss of overall thermal efficiency of the wall system with an increase in installed cost. Furthermore, the use of cement board and /or polymer modified mortars in lieu of lath and scratch offers further significant weight reductions below the suggested value of 25 pounds per square foot. After all, polymer modified mortars are less dense than conventional sanded mortars (type S or N). Finally, selecting a non metal lath product can once again result in a total façade weight reduction. Again, adopting a single façade weight of 25 psf is an incomplete and overly simplified approach. A fastener selection based on actual total façade weight is a complete and recommended solution. For example, for a steel stud structure with 2 of foam continuous insulation, the solutions are as follows: 15 psf total façade weight: #8 screw 18 psf total facade weight: #10 screw 22 psf total façade weight: #12 screw 25 psf total façade weight: #14 screw Regards, Rick Garagliano Director of Technical Sales Headwaters Stone Division

6 Everett, WA, US

7 January 5, 2014 ICC Evaluation Service, LLC Chicago Regional Office 4051 W Flossmoor Road Country Club Hills, IL SUBJECT: Potential Revisions to the Acceptance Criteria for Precast Stone Veneer, Subject AC R1 (EL/BJ) To Whom It May Concern: Thank you for the opportunity to provide input on potential changes to ICC-ES AC-51. The National Concrete Masonry Association (NCMA) is the national trade organization representing manufacturers of manufactured stone veneer products and as such AC51 is certainly important to us and our membership. NCMA represents producers of many manufactured concrete products, including manufactured stone veneer (also known as precast stone veneer and adhered manufactured stone masonry veneer ) that are a part of the Masonry Veneer Manufacturer s Association (MVMA), which is a part of NCMA. The discussion items included in the open later dated December 1, 2014 to all parties interested in precast stone veneer have been reviewed by the technical staff at NCMA with contributions from constituency of our manufactured stone veneer members. The review of the AC-51 document has given rise to a number of valid questions, particularly related to the sampling procedures of testing and verification of pertinent physical attributes such as average thickness and saturated unit weight. Further, the comparison of the AC-51 document and the related ASTM C1670, Standard Specification for Adhered Manufactured Stone Masonry Veneer (AMSMV) Units, has clearly defined the differences in requirements for testing and related properties. It should first be brought to the attention of those involved in the review of the AC-51 document, that there is a more current version of the ASTM standard than the 2013 version, referenced in the letter from ICC-ES. The most recent version at the time of developing these comments is ASTM C1670/C1670M-14. This updated version has incorporated changes that bring some clarity to sampling, testing, and physical requirements which may resolve some of the questions posed in the open letter. Specifically, the open letter has several questions relating to number of units to evaluate for dimensions and installed weight. While this issue continues to be debated within ASTM Committees, the most recent version of ASTM C1670/C1670M does address minimum numbers of units to sample for various tests. NCMA does not share the interpretation offered by ICC-ES that ASTM C1670/C1670M requires evaluation of every unit for weight. The standard, requires testing on a representative sample, and that all units are intended to be manufactured to comply with the code requirements for dimensions and weight, but evaluation of every unit shape would be onerous and unnecessary. ASTM C1670/C1670M-14 is the result of over eight years of standard development at ASTM, with significant input from manufactured stone veneer producers, users, and many other interested parties. The requirements within this standard are those necessary to assure quality of manufactured stone units, and units complying with these requirements meet all necessary code provisions for these units. Rather than create a second set of similar requirements, AC-51 should simply reference ASTM C1670/C1670M-14 for physical requirements for manufactured stone veneer units. This is consistent with how other materials within AC 51 are handled (for example, ASTM C926 is referenced for cement plaster). This change would also simplify the marketplace for both producers of these products as well as users, since only a single set of physical requirements would exist for these materials. In addition, an ASTM standard for installation of manufactured stone veneer systems has been developed. ASTM C , Standard Practice for Adhered Manufactured Stone Masonry Veneer, provides minimum standards for installation of manufactured stone veneer systems over a wide range of structural back-up systems. It is also the opinion of this organization and its members that AC 51 reference ASTM C1780 for installation practices. As part of these comments, attached is a marked-up version of AC-51 with proposed revisions from NCMA to establish a compliance path for units to meet ASTM C1670/C1670M, and with installation methods to comply with ASTM C1780. It is acknowledged that there may be other systems besides those covered under these standards that may utilize AC-51, so a compliance path using the current AC-51 revisions is maintained (with some minor modifications to simplify testing requirements in some places). Also contained in this markup are some other editorial and minor revisions with the intent to improve the overall content of AC-51.

8 The longstanding goal in the development of these standards has been formal reference in TMS 402/602, Building Code Requirements and Specifications of Masonry Structures. Upon formal adoption, which in turn would make these standards part of the International Building and Residential Codes by reference, the need to coordinate AC-51 with these standards becomes more important. With that, AC51 should reference developed consensus standards for both unit requirements (ASTM C1670/C1670M- 14) as well as installation practices (ASTM C1780) for manufactured stone veneer systems. Thank you again for the opportunity to comment, Dominick O. Dowds Manager, Research and Development Laboratory

9 (800) (562) A Subsidiary of the International Code Council ACCEPTANCE CRITERIA FOR PRECAST STONE VENEER AC51 Approved February 2008 Effective March 1, 2008 (Editorially revised April 2012) Previously revised September 2010 PREFACE Evaluation reports issued by ICC Evaluation Service, LLC (ICC-ES), are based upon performance features of the International family of codes. (Some reports may also reference older code families such as the BOCA National Codes, the Standard Codes, and the Uniform Codes.) Section of the International Building Code reads as follows: The provisions of this code are not intended to prevent the installation of any materials or to prohibit any design or method of construction not specifically prescribed by this code, provided that any such alternative has been approved. An alternative material, design or method of construction shall be approved where the building official finds that the proposed design is satisfactory and complies with the intent of the provisions of this code, and that the material, method or work offered is, for the purpose intended, at least the equivalent of that prescribed in this code in quality, strength, effectiveness, fire resistance, durability and safety. This acceptance criteria has been issued to provide interested parties with guidelines for demonstrating compliance with performance features of the codes referenced in the criteria. The criteria was developed through a transparent process involving public hearings of the ICC-ES Evaluation Committee, and/or on-line postings where public comment was solicited. New acceptance criteria will only have an approved date, which is the date the document was approved by the Evaluation Committee. When existing acceptance criteria are revised, the Evaluation Committee will decide whether the revised document should carry only an approved date, or an approved date combined with a compliance date. The compliance date is the date by which relevant evaluation reports must comply with the requirements of the criteria. See the ICC-ES web site for more information on compliance dates. If this criteria is a revised edition, a solid vertical line ( ) in the margin within the criteria indicates a change from the previous edition. A deletion indicator ( ) is provided in the margin where any significant wording has been deleted. ICC-ES may consider alternate criteria for report approval, provided the report applicant submits data demonstrating that the alternate criteria are at least equivalent to the criteria set forth in this document, and otherwise demonstrate compliance with the performance features of the codes. ICC-ES retains the right to refuse to issue or renew any evaluation report, if the applicable product, material, or method of construction is such that either unusual care with its installation or use must be exercised for satisfactory performance, or if malfunctioning is apt to cause injury or unreasonable damage. NOTE: The Preface for ICC-ES acceptance criteria was revised in July 2011 to reflect changes in policy. Acceptance criteria are developed for use solely by ICC-ES for purpose of issuing ICC-ES evaluation reports. Copyright 2012

10 ACCEPTANCE CRITERIA FOR PRECAST STONE VENEER (AC 51) 1.0 INTRODUCTION 1.1 Purpose: The purpose of this criteria is to establish the minimum requirements for recognition of adhered precast stone veneer in ICC Evaluation Service, LLC (ICC-ES), evaluation reports under the 2015, 2012, 2009 and 2006 International Building Code (IBC), and the 2015, 2012, 2009 and 2006 International Residential Code (IRC). This criteria is needed to clarify the requirements for composition, strength, durability and installation of precast stone veneer, which are not addressed in the code. 1.2 Scope: This criteria applies to precast stone veneer adhered with mortar to the exterior face of exterior walls and, at the report applicant s option, to interior wall surfaces. The veneer system is considered a variation of exterior plaster regulated by IBC Section 2512, and 2015 IRC Section R703.7 (Section R703.6 of the 2012, 2009 and 2006 IRC), and a variation of adhered masonry veneer regulated by IBC Section (Section of the 2006 IBC). The veneer may be adhered to backings consisting of concrete, masonry or cement plaster mortar applied over metal or wire fabric lath. 1.3 Codes and Reference Standards: Where standards are referenced in this criteria, the standards shall be applied consistent with the requirements of the applicable code. Editions of the standards applicable to each code are summarized in Table ASTM International: ASTM C33/C33M, Specification for Concrete Aggregates ASTM C39/C39M-99ae1, Test Method for Compressive Strength of Cylindrical Concrete Specimens ASTM C67, Test Methods for Sampling and Testing Brick and Structural Clay Tile ASTM C144-02, Specifications for Aggregate for Masonry Mortar ASTM C150, Specification for Portland Cement ASTM C109/C109M, Standard Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2- in. or [50 mm] Cube Specimens) ASTM C140/C140M, Test Methods for Sampling and Testing Concrete Masonry Units and Related Units ASTM C190-85, Test Method for Tensile Strength of Hydraulic Cement Mortars ASTM C192/C192M-81, Practice for Making and Curing Concrete Test Specimens in the Laboratory ASTM C330/C330M, Specification for Lightweight Aggregates for Structural Concrete ASTM C331/C331M, Specification for Lightweight Aggregates for Concrete Masonry Units ASTM C348-86, Test Method for Flexural Strength of Hydraulic Cement Mortars ASTM C482-02, Test Method for Bond Strength of Ceramic Tile to Portland Cement ASTM C567-05a, Test Method for Unit Weight of Structural Lightweight Concrete ASTM C926, Specification for Application of Portland Cement-based Plaster ASTM C1325, Specification for Non-Asbestos Fiber-Mat Reinforced Cement Substrate Sheets ASTM C1670/C1670M, Specification for Adhered Manufactured Stone Masonry Veneer Units ASTM C1780, Practice for Installation Methods for Adhered Manufactured Stone Masonry Veneer ASTM E84, Test Method for Surface Burning Characteristics of Building Materials ASTM E119, Test Methods for Fire Tests of Building Construction and Materials TMS /ACI 530/ASCE 5, Building Code Requirements for Masonry Structures (TMS 402), The Masonry Society, American Concrete Institute, Structural Engineering Institute of the American Society of Civil Engineers TMS 602/ACI 530.1/ASCE 6, Specification for Masonry Structures (TMS ), The Masonry Society, American Concrete Institute, Structural Engineering Institute of the American Society of Civil Engineers ACI 318 Building Code Requirements for Structural Concrete, American Concrete Institute UL 263, Fire Tests for Building Construction and Materials, Underwriters Laboratories UL 723, Test for Surface Burning Characteristics of Building Materials, Underwriters Laboratories. Comment [NL1]: Plaster is not used often as a scratch coat or setting bed. Mortar is more commonly used.

11 ACCEPTANCE CRITERIA FOR PRECAST STONE VENEER (AC 51) , 2012, 2009 and 2006 International Building Code (IBC), International Code Council , 2012, 2009 and 2006 International Residential Code (IRC), International Code Council Acceptance Criteria for Reinforced Cementations Sheets Used as Wall and Ceiling Sheathing and Floor Underlayment (AC376), ICC Evaluation Service, LLC. 1.4 Definitions: Backing: The surface to which the veneer units are adhered. The backing may be concrete, masonry or a scratch coat of cement plaster or masonry mortar applied over metal or wire fabric lath Veneer: A facing attached to a wall for the purpose of providing ornamentation, protection or insulation, but not counted as adding strength to the wall Adhered Veneer: A veneer secured and supported by adhesion with an approved bonding material applied over an approved backing Precast Stone Veneer: An adhered veneer made from lightweight precast concrete, comprised of cement, water and mineral aggregates, with or without other materials. Units of precast stone veneer are formed and cast off-site to provide the appearance of stone or other masonry materials Pattern: The repeating combination of veneer units and mortar joints used to produce the finished architectural effect Scratch Coat: A backing of cement plaster or masonry mortar applied over metal or wire fabric lath, to which the veneer units are adhered Veneer System: The combination of the veneer units with the supporting materials used to affix the veneer units to the supporting wall, including joint mortar, setting bed, and scratch coat, as applicable. 2.0 BASIC INFORMATION AND REPORTS OF TESTS 2.1 General: The following basic information shall be submitted: Product Description: Veneer Materials: Units and constituent materials used shall comply with either ASTM C1670/C1670M or the requirements listed below.a description of the constituent materials of the lightweight concrete used to form the precast stone veneer units in accordance with the following: Provide a description of the constituent materials of the lightweight concrete used to form the precast stone veneer units in accordance with the following: Cement: Type and description in accordance with Section of ACI Sand: Sand shall be clean and free from deleterious amounts of loam, clay, silt, soluble salts and organic matter. Sampling, testing and gradation shall comply with ASTM C Aggregate: Type and size designation must comply with ASTM C33/C33M, ASTM C330/C330M or ASTM C331/C331M, except gradation requirements need not apply. Gradation, however, shall be specified Admixtures: Description and purpose of the admixture shall be specified. Purposes may include, but not be limited to, expediting setting, enhancing durability and improving workability Colors: To be indicated as surface or integral. Integral color material shall be an inorganic type that is nonreactive with the aggregate, cement and other admixtures Mix Design: For each mix design to be recognized, all of the constituent materials and their proportions must be listed Veneer Units: Unit Physical Properties: The specified density and compressive strength of the precast stone veneer units must be provided Unit Dimensions: The range of sizes and shapes of the veneer units must be provided. Veneer units are limited to 36 inches (914 mm) in the greatest dimension and 720 square inches ( mm2) in total area. For installation under the IBC and IRC, the minimum and maximum average thicknesses of the veneer units are 1/45/8 inch and 2 5/8 inches ( and 67 mm), respectively. For installation under the BNBC and SBC, the veneer units shall be less than 15/8 inches (41 mm) thick Veneer System: System Components: System components shall comply with either ASTM C1780 or the requirements listed below Mortar: There must be a description of the type of mortar used for the setting bed and/or scratch coat. Mortar must comply with 2015 IBC Section (2012 IBC Section and 2009 and 2006 IBC Section ), and 2015 IRC Section R (2012, 2009, and 2006 IRC Section R607.1), as applicable. The thickness of the Comment [NL3]: This is not necessary. This is discussing the sand used in the mix design of the units. It is already covered in the next section. Comment [NL4]: This change is consistent with Table in 2012 IBC. Comment [NL5]: The revisions to this section create two compliance paths one for materials and methods that comply with ASTM C1780, and one for other installations. Comment [NL2]: The revisions to this section create two compliance paths one for units complying with ASTM C1670/C1670M, and another for other units.

12 ACCEPTANCE CRITERIA FOR PRECAST STONE VENEER (AC 51) setting bed must be described. The setting bed shall be a minimum of 3/8 inch (9.5 mm) thick and a maximum of 1¼ inches (32 mm) thick Cement Plaster: If applicable, the type of plaster used for the scratch coat, in accordance with ASTM C926, must be described Lath: The type and weight of the lath and the type, size and spacing of the fasteners used to attach the lath to the supporting structure must be described. The lath and its installation shall comply with IBC Section 2510, or IRC Section R703.6, as applicable Reinforced Cementitious Sheets: The type and thickness of reinforced cementitious sheets complying with ASTM C1325, Type A, and with ICC-ES AC376, shall be described. The allowable transverse load and installation shall be as described in a valid ICC-ES evaluation report on the reinforced cementitious sheets Physical Properties and Dimensions: A description of each pattern to be recognized; the average weight of the installed system for each pattern; the overall thickness of the system Veneer Manufacture: Information submitted in accordance with Appendix A of the ICC-ES Acceptance Criteria for Quality Documentation (AC10) must include the standard procedure for manufacture of the precast stone veneer units. This shall include material proportions, mixing instructions (including equipment used), methods used for forming the mixture into proper shapes, curing requirements and storage requirements Installation Instructions: The installation instructions must comply with one of the following: ASTM C1780 and IBC Section ; IBC Sections and ; or The requirements provided below: The installation instructions must comply with IBC Sections , and ; and Sections and of TMS (or Sections and of TMS and -08 and Sections and of ACI 530) and Article 3.3C of TMS 602, or ACI 530.1, as applicable. Where the veneer units are installed directly onto the uncured mortar setting bed (brown coat) without a paste of neat portland cement, as described in Article 3.3C of TMS 602 (or ACI 530.1), the shear bond of veneer units to the backing must be determined in accordance with Section of this criteria Except when installation is over concrete or masonry walls, a water-resistive barrier is required under the precast stone veneer system. The water-resistive barrier shall comply with IBC Sections and or with IRC Sections R703.2 and R , as applicable General: Instructions shall address each type of backing, and the structural support system intended, including metal studs, wood studs, masonry and concrete, in all interior and exterior locations. At a minimum, instructions shall include: a. Lath type and lath installation, including fastening requirements. b. Portland cement plaster preparation and installation. c. Masonry or concrete surface preparation. d. Mortar preparation, application, thickness and curing instructions. e. Application of water-resistive barrier. f. Ambient temperatures for application of veneer. g. Width of mortar joints Where the veneer units are installed directly onto the uncured mortar setting bed (brown coat) without a paste of neat portland cement (as described in TMS 602), the shear bond of the veneer units to the backing must be determined in accordance with Section of this critera Except when installation is over concrete or masonry walls, a water-resistive barrier is required under the precast stone veneer system. The water-resistive barrier shall comply with IBC Sections and or with IRC Sections R703.2 and R , as applicable Product Identification and Labeling: The method of packaging and identifying components shall be specified. A label on the packaging of the veneer, or on each piece of veneer, shall bear the manufacturer s name, the product name, the pattern name and the ICC-ES evaluation report number. 2.2 Testing Laboratories: Testing laboratories must comply with Section 2.0 of the ICC-ES Acceptance Criteria for Test Reports (AC85) and Section 4.2 of the ICC-ES Rules of Procedure for Evaluation Reports. 2.3 Test Reports: Test reports must comply with AC85 and include the following: 1. Witnessing of production, fabrication and installation of test specimens. Comment [NL7]: This information is covered in ASTM C1780, so it is only necessary for installations not complying with that standard. Comment [NL6]: Reference to ASTM C1780 should be an acceptable in lieu of specific instructions. An alternative for system specific instructions is still maintained.

13 ACCEPTANCE CRITERIA FOR PRECAST STONE VENEER (AC 51) 2. Preparation of test specimens, including complete description of the specimen components, mix proportions and curing. 3. Description of test procedures, along with details. 4. Test observations, including description of veneer before and after testing. Description shall be supported by photographs. 5. Statement as to whether the test results meet the conditions of acceptance given in the criteria. 6. Descriptions of veneer units sampled. 7. Unless noted otherwise, age of specimens following molding or fabrication. Tests must be conducted within 45 days of specimen preparation. 8. Sample curing or conditioning procedures. 2.4 Product Sampling: Test specimens must be representative of standard manufacture. The test specimens must be sampled in accordance with Sections 3.1, 3.3 and 3.4 of AC TEST AND PERFORMANCE REQUIREMENTS 3.1 Veneer Units: For each mix design to be recognized, test data documenting compliance with ASTM C1670/C1670M must be submitted. As an alternative, data in accordance with Sections to must may be submitted Alternatively, where Where more than one mix design is to be recognized, each test data for each mix design in accordance with ASTM C1670/C1670M must be submitted, or a testing program must be submitted to ICC-ES for approval prior to the commencement of testing. At a minimum, this testing program must include the following: the mix design(s) to be tested, the mix designs that are to be qualified based on the testing, and justification for the selection of the mix design(s) to be tested Density: The density of veneer units to be included in the evaluation report shall be the oven-dry density determined in accordance with ASTM C140/C140M.C567. The density may be determined by measurement or by calculation as allowed by ASTM C567. When the density is determined by measurement, five samples must be tested and the average density shall be reported Weight: The average saturated weight of the veneer units in each pattern, per unit area of wall, shall be determined in accordance with Section The average saturated weight must not exceed 15 pounds per square foot (73 kg/m2). The testing laboratory is permitted to verify compliance of a manufacturer s multiple patterns with the 15-pounds-per-square-foot requirement by evaluating the pattern that has been determined to have the highest average thickness with the heaviest density mixture used for that pattern Strength Requirements: Compressive strength tests of veneer mixture must be conducted in accordance with Section Minimum requirements are 1800 psi (12.4 MPa) average for five specimens. The results for any one sample cannot vary by more than 10 percent from the average for all samples Tensile strength tests of veneer mixture must be conducted in accordance with Section The results for any one sample cannot vary by more than 10 percent from the average for all samples Flexural tests of veneer mixture must be conducted in accordance with Section The results for any one sample cannot vary by more than 10 percent from the average for all samples The bond strength between the veneer unit, the mortar setting bed and the backing shall be determined in accordance with Section The test series must be repeated for each combination of mortar type and type of backing to be recognized. The shearing strength must be a minimum of 50 pounds per square inch (345 kpa). Individual bond strength result shall be within 20 percent of the average strength results, or the lowest individual bond strength result shall be a minimum of 50 pounds per square inch (345 kpa) Absorption: Veneer units must be tested for water absorption in accordance with Section Precast stone veneer units must comply with the water-absorption requirements in Table Freeze-Thaw: Resistance to freezing and thawing shall be tested in accordance with Section Test samples must not break or disintegrate, and weight loss is limited to 3 percent of original weight Thermal Resistance (Optional): If thermal resistance (R-value) of the veneer units is to be addressed, the results of testing in accordance with an applicable test method must be submitted. 3.2 Interior Finish (Optional): For precast stone veneer to be recognized for use as an interior finish, units shall either comply with ASTM C1670/C1670M or a report of testing in accordance with ASTM E84 or UL723 must be submitted to determine the interior finish classification. 3.3 Fire-resistance-rated Construction (Optional): Testing in accordance with ASTM E119 or UL 263 is required if fire resistance- rated recognition is sought. Comment [NL8]: These revisions establish two compliance paths either ASTM C1670/C1670M or the requirements in the AC. Comment [NL9]: ASTM C140/C140 is a simpler procedure for absorption, consistent with other masonry materials, and is consistent with ASTM C1670/C1670M. Comment [NL10]: Units complying with ASTM C1670/C1670M will inherently be non-combustible and comply with ASTM E84 requirements for interior finish, so testing is not necessary.

14 ACCEPTANCE CRITERIA FOR PRECAST STONE VENEER (AC 51) 4.0 TEST PROCEDURES 4.1 Units evaluated in accordance with ASTM C1670/C1670M shall use all test procedures referenced within that standard. For other units, the following procedures shall be used Weight: 1. The average saturated weight of the veneer units shall be determined by the testing laboratory. 2. The laboratory shall document how the volume of veneer per unit area of wall is determined. 3. The oven-dry density determined in accordance with Section shall be increased by the percentage of water absorption determined in accordance with Section and multiplied by the volume of veneer per unit area of wall to determine the average saturated weight Freeze-thaw Test: 1. Procedures follow those outlined in ASTM C67. Veneer specimens must be a minimum of 2 inches (51 mm) square by the minimum thickness to be recognized. At least five samples at the minimum thickness are required. 2. The specimens are subjected to 50 cycles of freezing and thawing, unless test specimens break or appear to have lost more than 3 percent of their original weight, as judged by the original inspection. 3. Weight loss is determined as a percentage of the original weight of the dry specimens. The number of cycles causing disintegration of the specimen must be reported. The manner of breakage or disintegration must be reported in detail Compressive Strength: 1. Compressive strength tests are conducted on cylinders of veneer mixture prepared, cured, and tested in accordance with ASTM C192/C192M and ASTM C39/C39M. A minimum of five samples must be tested. 2. The samples are cured in accordance with the standard and then tested at the age of 28 days. 3. Reporting procedures shall comply with the standard. The maximum compressive load imposed on each sample is reported, along with the compressive strength in pounds per square inch Flexural Strength: 1. Flexural strength tests of veneer mixture are conducted on samples prepared and tested in accordance with ASTM C348. A minimum of five samples is necessary. 2. After casting and prior to the specimens' being subjected to the load test after 28 days, the specimens shall be covered immediately after finishing, preferably with a nonabsorptive, nonreactive plate or a sheet of tough, durable, impervious plastic. Wet burlap may be used for covering, but care must be exercised to keep the burlap wet until the specimens are removed from the molds. Placing a sheet of plastic over the burlap will facilitate keeping it wet. Specimens shall be removed from the molds not less than 20 nor more than 48 hours after casting. While in storage, for a minimum period of 20 hours immediately prior to testing, they shall be immersed in saturated-lime solution at /- 3 F (23 +/- 1 C). At the end of the curing period, between the time the specimen is removed from curing and the time testing is completed, drying of the surfaces shall be prevented. 3. Reporting procedures follow those specified in the standard. The report shall include the maximum load imposed and the flexural strength, calculated as set forth in Section 8 of ASTM C Tensile Strength: 1. Tensile strength tests of veneer mixture are conducted on samples prepared, stored and tested in accordance with ASTM C190. A minimum of five specimens is necessary. 2. Tests are conducted in accordance with the standard, approximately 28 days after molding of the specimens. 3. Reporting procedures follow those specified in the standard. The maximum load imposed and the tensile strength in pounds per square inch are to be reported Moisture Absorption: 1. A minimum of 10 samples is required.moisture absorption shall be conducted in accordance with ASTM C140/C140 on veneer units. 2. Samples shall be taken from pieces of broken veneer units. 32. The percent of water absorption based on dry weight shall be reported. 4. Procedure: Loose particles shall be removed by scrubbing with a fiber brush and clean water. Samples shall be dried in a well-ventilated oven for 24 hours at a temperature of 221 F (105 C) varying not more than 3.6 F(2.0 C). After drying, the samples may be cooled at room temperature for 15 minutes after identifying and weighing to the nearest 0.01 gram. The samples shall then be immersed in filtered or distilled water for 48 hours at a temperature of 68 F (20 C), varying not more than 9 F (5 C). One sample shall be removed, its surfaces wiped dry, and the sample weighed immediately. The process shall be repeated for each sample Shear Bond Strength: Comment [NL11]: This revision establishes ASTM C1670/C1670M testing requirements as sufficient for compliance. Alternative path to use AC-51 requirements instead maintained. Comment [NL12]: These revisions simplify moisture absorption to use the same procedures as that for density. Both properties can be determined from a single procedure.

15 ACCEPTANCE CRITERIA FOR PRECAST STONE VENEER (AC 51) Shear bond tests shall be conducted in accordance with ASTM C482, with the following modifications/clarifications: 1. A minimum of five samples shall be tested. 2. The cement plastermortar, masonry, or concrete backing shall be substituted for the cement mortar bed specified in Section 9 of ASTM C The cement plastermortar shall be allowed to cure in accordance with IBC Table and the manufacturer s installation instructions, before the veneer units are applied. 4. The veneer units shall be adhered to the backing using the mortar setting bed recommended by the manufacturer, in lieu of the pure portland cement paste specified in ASTM C482. The mortar type, thickness and method of application shall be described in the test report. The samples shall be cured in accordance with Section 9.7 of ASTM C Dimension C in Figure 3 of the standard may be modified to match the thickness of the test samples. 6. Where veneer specimens have a back pattern, the pattern shall be parallel to the direction of loading in the test setup Compressive strength tests shall be conducted in accordance with Section 4.3 on concrete cylinders prepared from the same batch of concrete as the veneer unit samples. The compressive strength shall be within 10 percent of the average compressive strength determined in accordance with Section Compressive strength tests shall be conducted on the mortar in accordance with ASTM C109/C109M. The compressive strength of the mortar shall not exceed the minimum specified compressive strength by more than 10 percent The maximum load and bond strength for each sample shall be reported. The mode of failure, i.e., failure of the veneer unit, bond of the unit to the mortar setting bed, or bond of the setting bed to the backing, shall be reported. 5.0 QUALITY CONTROL 5.1 Quality documentation complying with the ICC-ES Acceptance Criteria for Quality Documentation (AC10) shall be submitted for each facility manufacturing or labeling products that are to be recognized in the ICC-ES evaluation report. 5.2 For facilities manufacturing units complying with ASTM C1670/C1670M, third-party follow-up inspections are not required. 5.3 For facilities manufacturing units to comply with the physical requirements contained in this criteria, the following is required: A qualifying inspection shall be conducted at each manufacturing facility in accordance with the requirements of the ICC-ES Acceptance Criteria for Inspections and Inspection Agencies (AC304) An annual inspection shall be conducted at each manufacturing facility in accordance with AC EVALUATION REPORT RECOGNITION The evaluation report shall include the following: 6.1 A description of the veneer units, including either the required reporting information for ASTM C1670/C1670M or the information from Sections and and A description of the veneer system, through either a reference to ASTM C1780 or the information rom Basic procedures for installation of precast stone veneer onto each type of backing, or a reference to ASTM C1780 for installation Requirements for water-resistive barrier, flashing and weep screeds, or a reference to ASTM C1780 for this information. For installations under the IBC and IRC, weep screeds and flashing shall comply with 2012 IBC Section Weep screeds shall have weepholes at least 3/16 inch (4.8 mm) in diameter, spaced less than 33 inches (838 mm) on center, in accordance with Section of TMS (Section of TMS and -08), or Section of ACI 530 as applicable Clearance of exterior veneer from earth, paving or exterior walking surfaces shall comply with 2015 and 2012 IBC Section The evaluation report shall include the following conditions of use: Expansion or control joints used to limit the effect of differential movement of precast stone veneer supports must be specified by the architect, designer or veneer manufacturer, in that order. Consideration must be given to movement caused by temperature changes, shrinkage, creep and deflection For installation in accordance with the IBC, BNBC, SBC and UBC, supporting wall construction must be designed to support the weight of the veneer system. Horizontal framing members, such as lintels and headers, which support Comment [NL14]: When ASTM C1670/C1670M is used for units, and/or ASTM C1780 is used for installation, references to the requirements of those documents should be sufficient for report compliance. Comment [NL13]: Inspections should not be necessary for units complying with an established ASTM standard.

16 ACCEPTANCE CRITERIA FOR PRECAST STONE VENEER (AC 51) precast stone veneer, must be designed to limit deflection to 1/600 of the span In jurisdictions adopting the IRC, where the seismic provisions of Section R apply, the average weight of the wall supporting the precast stone veneer, including the weight of the veneer system, must be determined. When this weight exceeds the applicable limits of IRC Section , an engineered design of the wall construction must be performed in accordance with IRC Section R When applicable, reinforced cementitious sheets must be recognized in a valid ICC-ES evaluation report. Comment [NL15]: This table will need to be updated to reflect changes to document above.