ASTM C926-21

Standard Specification for Application of Portland Cement-Based Plaster

ABSTRACT
This specification covers the standard requirements for the application of full thickness Portland cement-based plaster for exterior (stucco) and interior work. It also sets forth tables for proportioning of various plaster mixes and plaster thickness. The materials used shall consist of the following: cement which shall be a Portland cement, air-entraining Portland cement, masonry cement, blended hydraulic cement, air-entraining blended hydraulic cement, or plastic cement; Type S hydrated lime; aggregates such as perlite and sand for base and job-mixed finish coats; water to be used in mixing; admixtures; and fibers. Surfaces of solid bases such as masonry, stone, cast-in-place or precast concrete shall be prepared either by sandblasting, wire brushing, acid etching, chipping, or a combination thereof. Details on curing to resist cracking; materials protection and storage; environmental conditions; and application of plaster, finish-coat, and fog-coat, which shall be done by hand or machine up to the specified nominal thickness on metal and solid plaster bases are discussed.
SCOPE
1.1 This specification covers the minimum technical requirements for the application of full thickness portland cement-based plaster for exterior (stucco) and interior work. These requirements do not by default define a unit of work or assign responsibility for contractual purposes, which is the purview of a contract or contracts made between contracting entities.  
1.2 This specification sets forth tables for proportioning of various plaster mixes and plaster thickness.  
Note 1: General information will be found in Annex A1. Design considerations will be found in Annex A2.  
1.3 The text of this specification references notes and footnotes that provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the specification.  
1.4 Details of construction for a specific assembly to achieve the required fire resistance shall be obtained from reports of fire-resistance tests, engineering evaluations, or listings from recognized fire testing laboratories.  
1.5 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Historical
• Publication Date: 30-Sep-2021
• ICS: 91.100.10 - Cement. Gypsum. Lime. Mortar
• Technical Committee: C11 - Gypsum and Related Building Materials and Systems
• Drafting Committee: C11.03 - Specifications for the Application of Gypsum and Other Products in Assemblies

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:C926 −21
Standard Specification for
1
Application of Portland Cement-Based Plaster
This standard is issued under the fixed designation C926; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 2. Referenced Documents
2
2.1 ASTM Standards:
1.1 This specification covers the minimum technical re-
C11Terminology Relating to Gypsum and Related Building
quirements for the application of full thickness portland
Materials and Systems
cement-based plaster for exterior (stucco) and interior work.
C25Test Methods for Chemical Analysis of Limestone,
These requirements do not by default define a unit of work or
Quicklime, and Hydrated Lime
assign responsibility for contractual purposes, which is the
C35Specification for InorganicAggregates for Use in Gyp-
purview of a contract or contracts made between contracting
sum Plaster
entities.
C91/C91MSpecification for Masonry Cement
1.2 This specification sets forth tables for proportioning of
C150/C150MSpecification for Portland Cement
various plaster mixes and plaster thickness.
C206Specification for Finishing Hydrated Lime
C207Specification for Hydrated Lime for Masonry Pur-
NOTE 1—General information will be found in Annex A1. Design
poses
considerations will be found in Annex A2.
C219Terminology Relating to Hydraulic and Other Inor-
1.3 The text of this specification references notes and
ganic Cements
footnotes that provide explanatory material. These notes and
C260/C260MSpecification for Air-Entraining Admixtures
footnotes (excluding those in tables and figures) shall not be
for Concrete
considered as requirements of the specification.
C578Specification for Rigid, Cellular Polystyrene Thermal
Insulation
1.4 Details of construction for a specific assembly to
C595/C595MSpecification for Blended Hydraulic Cements
achieve the required fire resistance shall be obtained from
C631Specification for Bonding Compounds for Interior
reports of fire-resistance tests, engineering evaluations, or
Gypsum Plastering
listings from recognized fire testing laboratories.
C897Specification for Aggregate for Job-Mixed Portland
1.5 Thevaluesstatedininch-poundunitsaretoberegarded
Cement-Based Plasters
as standard. The values given in parentheses are mathematical
C932 Specification for Surface-Applied Bonding Com-
conversions to SI units that are provided for information only
pounds for Exterior Plastering
and are not considered standard.
C1063Specification for Installation of Lathing and Furring
to Receive Interior and Exterior Portland Cement-Based
1.6 This international standard was developed in accor-
Plaster
dance with internationally recognized principles on standard-
C1116/C1116MSpecificationforFiber-ReinforcedConcrete
ization established in the Decision on Principles for the
C1328Specification for Plastic (Stucco) Cement
Development of International Standards, Guides and Recom-
C1787Specification for Installation of Non Metallic Plaster
mendations issued by the World Trade Organization Technical
Bases (Lath) Used with Portland Cement Based Plaster in
Barriers to Trade (TBT) Committee.
Vertical Wall Applications
E90Test Method for Laboratory Measurement of Airborne
Sound Transmission Loss of Building Partitions and
1
This specification is under the jurisdiction of ASTM Committee C11 on
Elements
GypsumandRelatedBuildingMaterialsandSystemsandisthedirectresponsibility
ofSubcommitteeC11.03onSpecificationsfortheApplicationofGypsumandOther
2
Products in Assemblies. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2021. Published October 2021. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1981. Last previous edition approved in 2020 as C926–20b. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/C0926-21. the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
C926−21
E119Test Methods for Fire Tests of Building Construction 3.2.11.2 bedding coat, n—a plaster coat that receives aggre-
and Materials gate or other decorative material impinged into its surface
E492Test Method for Laboratory Measurement of Impact before it sets.
Sound Transmission Through Floor-Ceiling Assemblies
3.2.11.3 brown coat, n—inthree-coatwork,thesecondcoat,
Using the Tapping Machine
applied over the scratch coat. In two-coat work, brown coat
3
2.2 ANSI Standard:
refers to the double
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: C926 − 20b C926 − 21
Standard Specification for
1
Application of Portland Cement-Based Plaster
This standard is issued under the fixed designation C926; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This specification covers the minimum technical requirements for the application of full thickness portland cement-based
plaster for exterior (stucco) and interior work. These requirements do not by default define a unit of work or assign responsibility
for contractual purposes, which is the purview of a contract or contracts made between contracting entities.
1.2 This specification sets forth tables for proportioning of various plaster mixes and plaster thickness.
NOTE 1—General information will be found in Annex A1. Design considerations will be found in Annex A2.
1.3 The text of this specification references notes and footnotes that provide explanatory material. These notes and footnotes
(excluding those in tables and figures) shall not be considered as requirements of the specification.
1.4 Details of construction for a specific assembly to achieve the required fire resistance shall be obtained from reports of
fire-resistance tests, engineering evaluations, or listings from recognized fire testing laboratories.
1.5 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2
2.1 ASTM Standards:
C11 Terminology Relating to Gypsum and Related Building Materials and Systems
C25 Test Methods for Chemical Analysis of Limestone, Quicklime, and Hydrated Lime
C35 Specification for Inorganic Aggregates for Use in Gypsum Plaster
C91/C91M Specification for Masonry Cement
C150/C150M Specification for Portland Cement
C206 Specification for Finishing Hydrated Lime
C207 Specification for Hydrated Lime for Masonry Purposes
1
This specification is under the jurisdiction of ASTM Committee C11 on Gypsum and Related Building Materials and Systems and is the direct responsibility of
Subcommittee C11.03 on Specifications for the Application of Gypsum and Other Products in Assemblies.
Current edition approved Sept. 15, 2020Oct. 1, 2021. Published October 2020October 2021. Originally approved in 1981. Last previous edition approved in 2020 as
C926 – 20a.C926 – 20b. DOI: 10.1520/C0926-20B.10.1520/C0926-21.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
C926 − 21
C219 Terminology Relating to Hydraulic and Other Inorganic Cements
C260/C260M Specification for Air-Entraining Admixtures for Concrete
C578 Specification for Rigid, Cellular Polystyrene Thermal Insulation
C595/C595M Specification for Blended Hydraulic Cements
C631 Specification for Bonding Compounds for Interior Gypsum Plastering
C897 Specification for Aggregate for Job-Mixed Portland Cement-Based Plasters
C932 Specification for Surface-Applied Bonding Compounds for Exterior Plastering
C1063 Specification for Installation of Lathing and Furring to Receive Interior and Exterior Portland Cement-Based Plaster
C1116/C1116M Specification for Fiber-Reinforced Concrete
C1328 Specification for Plastic (Stucco) Cement
C1787 Specification for Installation of Non Metallic Plaster Bases (Lath) Used with Portland Cement Based Plaster in Vertical
Wall Applications
E90 Test Method for Laboratory Measurement of Airborne Sound Transmission Loss of Building Partitions and Elements
E119 Test Methods for Fire Tests of Building Construction and Materials
E492 Test Method for Laboratory
...