ASTM_C_842_-_05_2015.pdf

Designation:C84205(Reapproved 2015)Standard Specification forApplication of Interior Gypsum Plaster1This standard is issued under the fixed designation C842;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This specification covers the minimum requirements forfull-thickness(in accordance with Table 1)interior gypsumplastering on gypsum,metal,masonry,or monolithic concretebases designed or prepared to receive gypsum plaster.1.1.1 Gypsum plaster applied to the interior side of exteriorwalls of masonry or concrete shall be isolated from the exteriorwall.1.2 Gypsum plasters shall not be used in exterior locationsor interior“wet”areas.NOTE1To secure desirable results,this specification should becoordinated with the provisions of Specification C841.General informa-tion concerning full thickness gypsum plastering is contained in AnnexA2,Annex A3,and Annex A4.1.3 Details of construction for a specific assembly toachieve the required fire resistance shall be obtained fromreports of fire-resistance tests,engineering evaluations,orlistings from recognized fire testing laboratories.1.4 Details of construction to achieve required sound con-trol shall be obtained from reports of tests conducted atrecognized sound testing laboratories in accordance with theapplicable sound tests of Test Methods E90,C423,or E492.1.5 The values stated in inch-pound units are to be regardedas the standard.The SI(metric)values given in parentheses areapproximate and are provided for information purposes only.1.6 The text of this standard references notes and footnoteswhich provide explanatory material.These notes and footnotes(excluding those in tables and figures)shall not be consideredas requirements of the standard.2.Referenced Documents2.1 ASTM Standards:2C5 Specification for Quicklime for Structural PurposesC11 Terminology Relating to Gypsum and Related BuildingMaterials and SystemsC28/C28M Specification for Gypsum PlastersC35 Specification for Inorganic Aggregates for Use in Gyp-sum PlasterC59/C59M Specification for Gypsum Casting Plaster andGypsum Molding PlasterC61/C61M Specification for Gypsum Keenes CementC206 Specification for Finishing Hydrated LimeC423 Test Method for SoundAbsorption and SoundAbsorp-tion Coefficients by the Reverberation Room MethodC631 Specification for Bonding Compounds for InteriorGypsum PlasteringC841 Specification for Installation of Interior Lathing andFurringC1489 Specification for Lime Putty for Structural PurposesE90 Test Method for Laboratory Measurement of AirborneSound Transmission Loss of Building Partitions andElementsE492 Test Method for Laboratory Measurement of ImpactSound Transmission Through Floor-Ceiling AssembliesUsing the Tapping Machine3.Terminology3.1 Definitions:3.1.1 Definitions shall be in accordance with TerminologyC11.3.2 Definitions of Terms Specific to This Standard:3.2.1 catfaces,nblemishes or rough depressions in thefinish coat.3.2.2 coat,na thickness or layer of plaster applied over asurface in a single application.3.2.2.1 base coat,nthe sum of the scratch and brown coatsor the total coats in place prior to application of finish coats.3.2.2.2 brown coat,nthe second coat of plaster applied inthree-coat work.3.2.2.3 finish coat,nthe last coat of plaster applied ineither two-coat or three-coat work.3.2.2.4 scratch coat,nthe first coat of plaster applied overa lath or other substrate.3.2.2.5 three-coat work,nplaster applied in three succes-sive coats,leaving time between coats for setting or drying,orboth,of the plaster.1This specification is under the jurisdiction of ASTM Committee C11 onGypsum and Related Building Materials and Systems and is the direct responsibilityof Subcommittee C11.03 on Specifications for theApplication of Gypsum and OtherProducts in Assemblies.Current edition approved Oct.1,2015.Published October 2015.Originallyapproved in 1976.Last previous edition approved in 2010 as C842 05(2010)1.DOI:10.1520/C0842-05R15.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.2.2.6 two-coat work,nscratch and brown coats appliedfrom the same mix with no time allowed for setting of thescratch coat before the brown coat is applied.3.2.3 gypsum ready mixed plaster,ncalcined gypsumplaster,mixed at the mill with a mineral aggregate,designed tofunction as a base coat to receive various finish coats.3.2.4 metal bases,nexpanded metal,welded or wovenwire,or punched sheet metal plaster bases.3.2.5 smooth-trowel finish,na finish resulting from steel