ASTM C841-03(2008)e1
(Specification)Standard Specification for Installation of Interior Lathing and Furring
Standard Specification for Installation of Interior Lathing and Furring
ABSTRACT
This specification covers the minimum requirements for, and the methods of application of, interior lathing and furring to receive gypsum plaster applied. Other materials are not prohibited from being used provided that their physical characteristics and durability under conditions of usage are at least equal in performance to those described. All materials shall be kept dry, preferably by being stored inside. Where necessary to be stored outside, materials shall be stacked off the ground, supported on a level platform, and protected from the weather and surface contamination. Materials shall be neatly stacked flat with care taken to avoid damage to edges, ends, or surfaces. The materials to be used are the following: tie wire and hanger wire, gypsum lath, expanded metal lath, welded wire lath, woven wire lath, nails, screws, staples, paper, and accessories such as control joints, cornerite, channels, rod and flat hangers, clips, and striplath. In general, during installation, the following shall be required: application of gypsum lath to supports, application of gypsum lath to wood supports, application of gypsum lath to metal supports, studless solid partitions (gypsum lath and plaster), application of metal plaster bases to framing members, studless solid partitions (metal lath and plaster), suspended and furred ceilings (metal lath and gypsum lath construction), main runners, cross furring, and metal furring for walls.
SCOPE
1.1 This specification covers the minimum requirements for, and the methods of application of, interior lathing and furring to receive gypsum plaster applied in accordance with Specification C 842. Other materials are not prohibited from being used provided that their physical characteristics and durability under conditions of usage are at least equal in performance to those described.
1.2 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.
1.3 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.
1.4 Where a specific degree of sound control is required for plastered assemblies and constructions, details of construction shall be obtained from reports of sound tests of assemblies that have met the requirements of Test Method E 492.
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´1
Designation:C841 −03(Reapproved2008)
Standard Specification for
Installation of Interior Lathing and Furring
This standard is issued under the fixed designation C841; 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.
This standard has been approved for use by agencies of the Department of Defense.
´ NOTE—The units statement in subsection 1.2 was corrected editorially in July 2008.
1. Scope C37/C37M Specification for Gypsum Lath (Withdrawn
2004)
1.1 Thisspecificationcoverstheminimumrequirementsfor,
C514 Specification for Nails for the Application of Gypsum
and the methods of application of, interior lathing and furring
Board
to receive gypsum plaster applied in accordance with Specifi-
C754 Specification for Installation of Steel Framing Mem-
cation C842. Other materials are not prohibited from being
bers to Receive Screw-Attached Gypsum Panel Products
used provided that their physical characteristics and durability
C842 Specification forApplication of Interior Gypsum Plas-
under conditions of usage are at least equal in performance to
ter
those described.
C847 Specification for Metal Lath
C933 Specification for Welded Wire Lath
1.2 The values stated in inch-pound units are to be regarded
C954 SpecificationforSteelDrillScrewsfortheApplication
as standard. The values given in parentheses are mathematical
of Gypsum Panel Products or Metal Plaster Bases to Steel
conversions to SI units that are provided for information only
Studs from 0.033 in. (0.84 mm) to 0.112 in. (2.84 mm) in
and are not considered standard.
Thickness
1.3 Details of construction for a specific assembly to
C1002 Specification for Steel Self-Piercing Tapping Screws
achieve the required fire resistance shall be obtained from
for the Application of Gypsum Panel Products or Metal
reports of fire-resistance tests, engineering evaluations, or
Plaster Bases to Wood Studs or Steel Studs
listings from recognized fire testing laboratories.
C1007 Specification for Installation of Load Bearing (Trans-
verse and Axial) Steel Studs and Related Accessories
1.4 Where a specific degree of sound control is required for
C1032 Specification for Woven Wire Plaster Base
plastered assemblies and constructions, details of construction
D1784 Specification for Rigid Poly(Vinyl Chloride) (PVC)
shall be obtained from reports of sound tests of assemblies that
Compounds and Chlorinated Poly(Vinyl Chloride)
have met the requirements of Test Method E492.
(CPVC) Compounds
D3678 Specification for Rigid Poly(Vinyl Chloride) (PVC)
2. Referenced Documents
Interior-Profile Extrusions
2.1 ASTM Standards: E492 Test Method for Laboratory Measurement of Impact
Sound Transmission Through Floor-Ceiling Assemblies
A641/A641M Specification for Zinc–Coated (Galvanized)
Carbon Steel Wire Using the Tapping Machine
C11 Terminology Relating to Gypsum and Related Building 2.2 National Association of Architectural Metal Manufac-
Materials and Systems turers Standard
HMMA 840 Installation and Storage of Hollow Metal Doors
and Frames
This specification is under the jurisdiction of ASTM Committee C11 on
3. Terminology
Gypsum and Related Building Materials and Systems and is the direct responsibility
ofSubcommitteeC11.03onSpecificationsfortheApplicationofGypsumandOther
3.1 Definitions—For definitions relating to ceilings and
Products in Assemblies.
walls see Terminology C11.
CurrenteditionapprovedMay1,2008.PublishedJuly2008.Originallyapproved
in 1976. Last previous edition approved in 2003 as C841 – 03. DOI: 10.1520/
C0841-03R08E01.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or The last approved version of this historical standard is referenced on
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM www.astm.org.
Standards volume information, refer to the standard’s Document Summary page on Available from NAAMM, 8 South Michigan Avenue, Suite 1000, Chicago, IL
the ASTM website. 60603.
*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
C841−03(2008)
3.2 Definitions of Terms Specific to This Standard:
Wire Gage (U.S. Steel
A
Diameter, in. (mm) Wire Gage)
3.2.1 base coat, n—the sum of the scratch and brown coats
0.0410 (1.04) No. 19
or the total coats in place prior to application of finish coats.
0.0475 (1.21) No. 18
3.2.2 contact ceiling, n—a ceiling in which the lath is
0.0540 (1.37) No. 17
0.0625 (1.59) No. 16
attached in direct contact with the construction above, without
0.0800 (2.03) No. 14
the use of main runners or cross furring.
0.0915 (2.32) No. 13
0.1055 (2.68) No. 12
3.2.3 furred ceiling, n—a ceiling in which the furring used
0.1205 (3.06) No. 11
for the support of the lath is attached directly to the structural
0.1350 (3.43) No. 10
members of the building.
0.1483 (3.77) No. 9
0.1620 (4.11) No. 8
3.2.4 suspended ceiling, n—a ceiling in which the main
_____________
runners and cross furring are suspended below the structural
A
Allowable variations in diameter shall be in accordance with tolerances as
members of the building.
established in A641/A641M.
3.2.5 main runners, n—the members that are attached to or
6.2 Gypsum Lath—Specification C37/C37M.
suspended from the construction above for the support of cross
6.3 Expanded Metal Lath—Specification C847.
furring.
3.2.6 cross furring, n—furring members that are attached at 6.4 Wire Lath:
right angles to the underside of the main runners or construc-
6.4.1 Welded Wire Lath, Specification C933.
tion above for support of the lath.
6.4.2 Woven Wire Lath, Specification C1032.
3.2.7 furring, n—spacer strips fastened to a wall, ceiling, or
6.5 Fasteners:
planarelementthatcreateanevensurfacefortheapplicationof
6.5.1 Nails for Attaching Gypsum Lath—Specification
metal plaster bases or gypsum lath.
C514. Nail size shall be in accordance with Table 1.
3.2.8 primary members, n—the members (main runners or
6.5.2 Nails for Attaching Metal Plaster Base—Galvanized
structural supports) to which the cross furring is attached.
roofing nails or common nails. length shall be as specified in 7.
3.2.9 metal plaster bases, n—expanded metal lath, sheet
6.5.3 Screws—Specifications C954 or C1002.
metal lath, welded or woven wire lath.
6.5.3.1 Screws for attaching gypsum lath shall be sized in
3.2.10 face side (gypsum lath), n—the side opposite the
accordance with Table 1.
paper cover seam laps.
6.5.3.2 Screws for attaching metal plaster base shall have a
3.2.11 surface transition, n—the change in width of a ⁄16 in. (11.1 mm) diameter pan washer head and a 0.120 in.
surface, usually as a result of penetrations (doors, windows) or (3.0 mm) diameter shank.The length shall be sufficient enough
architectural demands. toallowforthethreadedportionofthescrewtoprojectnotless
than ⁄8 in. (9.5 mm) through steel framing when the lath is
4. Delivery of Materials
installed.
4.1 All materials shall be delivered in the original packages, 6.5.4 Staples—Staples for attaching gypsum lath shall con-
containers, or bundles bearing the brand name and manufac- form to the requirements of Table 1.
turer’s (or supplier’s) identification.
6.5.4.1 Staples for attaching metal plaster base shall be
0.062 in. (1.6 mm) diameter, round or flattened steel wire with
5. Storage of Materials
⁄4 in. (19.0 mm) crown. Lengths shall be as specified for
individual systems.
5.1 All materials shall be kept dry, preferably by being
stored inside. Where necessary to be stored outside, materials
6.6 Paper or Other Backing—When used on metal plaster
shall be stacked off the ground, supported on a level platform,
bases, over solid backing, backing shall be securely held in
and protected from the weather and surface contamination.
place by, or attached to the metal plaster base. Metal plaster
5.2 Materials shall be neatly stacked flat with care taken to base shall allow for ⁄4 in. (6.4 mm) self furring. The backing
avoid damage to edges, ends, or surfaces.
shall permit embedment of plaster.
6.7 Accessories—Shall be steel, coated, with a protective
6. Materials
rust inhibitive coating after fabrication, or fabricated from
6.1 Wire Specification A641/A641M, Class 1 coating (gal-
zinc-coated (galvanized) steel, aluminum, zinc alloy, or high
vanized) soft temper.
impact plastic. Plastic accessories shall be nmanufactured in
6.1.1 Tie Wire and Hanger Wire—Zinc-coated (galvanized)
accordance with Specifcation D1784 or Specification D3678.
soft-annealed steel, or a material having equivalent size,
Aluminum accessories shall be clear plastic coated. All acces-
corrosion resistance and strength. Wire diameters (uncoated)
soriesshallhaveperforatedorexpandedflangesorclipsshaped
specified herein correspond with United States steel wire gage
so as to permit complete imbedment in the plaster, to provide
numbers as follows:
means for secure alignment, and to secure attachment of the
Wire Gage (U.S. Steel
accessory to the underlying surface. Accessories shall be
A
Diameter, in. (mm) Wire Gage)
designed for the intended use and to receive or to permit
0.0348 (0.88) No. 20
application of the specified plaster thickness.
´1
C841−03(2008)
A,B
TABLE 1 Screws, Nails and Staples for Attaching Gypsum Lath to Horizontal and Vertical Wood Supports
Maximum Spacing, in. (mm) Minimum Gage Requirements, in. (mm)
Diameter of
Flat Head or Gage of
Distance Number of Approximate Depth of
Width of Thickness Length of Blued Nails Shank of
Between Attachments Spacing c to c of Support
Lath of Lath Leg or Crown Nails or
Supports per Bearing Attachments Penetration
A
Width of Staples
A
Staples
3 1 3 19
16 (406) ⁄8 (9.5) 16 (406) 4 5 (127) 1 ⁄8 (28.6) ⁄4 (19) ⁄64 (7.5) 13
A A A A
5 7
1 (25.4) ⁄8 (15.9) ⁄16 (11) 16
3 1 1 3 19
24 (610) ⁄8 (9.5) 16 (406) 6 4 ⁄2 (114) 1 ⁄8 (28.6) ⁄4 (19) ⁄64 (7.5) 13
A A A A
5 7
1 (25.4) ⁄8 (15.9) ⁄16 (11) 16
1 1 3 19
16 (406) ⁄2 (12.7) 24 (610) 4 5 (127) 1 ⁄4 (32) ⁄4 (19) ⁄64 (7.5) 13
A A A A
1 5 7
1 ⁄8 (28.6) ⁄8 (15.9) ⁄16 (11) 16
1 1 1 3 19
24 (610) ⁄2 (12.7) 24 (610) 6 4 ⁄2 (114) 1 ⁄4 (32) ⁄4 (19) ⁄64 (7.5) 13 (330)
A A A A
1 5 7
1 ⁄8 (28.6) ⁄8 (15.9) ⁄16 (11) 16
3 1 1 3
48 (1219) ⁄8 (9.5) 16 (406) 8 4 ⁄2 (114) 1 ⁄8 (28.6) ⁄4 (19)
A A
1 5
⁄2 (12.7) 24 (610) 1 (25.4) ⁄8 (15.9)
1 3
1 ⁄4 (32) ⁄4 (19)
A A
1 5
1 ⁄8 (28.6) ⁄8 (15.9)
A
Galvanized staples.
B
Screws for attaching gypsum lath to wood supports shall be Type W as described in Specification C1002.
6.7.1 Thickness of base material for accessories shall be not zinc-coated (galvanized) steel wire or sheet, and of sufficient
less than as shown in the following: size and strength to support the intended load
6.7.7 Striplath—Shall be not less than 1.75 lb/yd (0.85
Base Material (mm) Thickness of
Base Material, in.
kg/m ) expanded metal lath, or woven or welded fabric of not
Uncoated steel/zinc 0.014 (0.36)
less than 0.041 in. (1.04 mm) thick weighing not less than 1.75
PVC 0.030 (0.76)
2 2
lb/yd (0.85 kg/m ) fabricated from galvanized steel.
Aluminum 0.050 (1.27)
6.7.2 Control Joints—Shall be formed by using a single
7. Installation
prefabricated member or fabricated by installing casing beads
7.1 General Requirements for Application of Lath and
back to back with a flexible barrier membrane behind casing
Accessories:
beads. The separation spacing shall be not less than ⁄8 in. (3.2
7.1.1 Lath shall be installed with the long dimension at right
mm) or as required by the anticipated thermal exposure range.
angles to supports, unless otherwise specified.
6.7.3 Cornerite—shall be not less than 1.75 lb/yd (0.85
7.1.2 Corner beads shall be installed to protect all external
kg/m ) expanded metal lath, galvanized, or given a protective
corners and to establish grounds. Corner beads shall be
coating of rust inhibitive paint after fabrication, or woven or
attached to the substrate in such a manner as to ensure proper
welded fabric not less than 0.041 in. (1.04 mm) thick an
2 2
alignment during application of plaster.
weighing not less than 1.75 lb/yd (0.85 kg/m ), fabricated
7.1.3 Metal accessories shall be installed so that flanges and
from galvanized wire. When shaped for angle reinforcing,
clipsprovidedfortheirattachmentarecoveredbythebasecoat
cornerite shall have outstanding legs of not less than 2 in. (50.8
plaster.
mm).
7.1.4 Control Joints—Shall be installed in ceilings greater
6.7.4 Channels—Shall be cold-rolled steel, free of rust with
2 2
than 2500 ft (232 m ) in area and in partition, wall, and wall
a coating of rust inhibitive paint or galvanized. Channels used
furring runs greater than 30 ft (9 m) in length. The distance
in areas subject to corrosive action of salt air or other corrosive
between ceiling control joints shall not be more than 50 ft (15
environments, shall be hot-dip galvanized. Weight of the
m) in either direction. A control joint shall be installed where
channel shall be not less than as shown in the following:
the ceiling framing or furring changes direction. The distance
Size Weight
betweencontroljointsinwallsorwallfurringshallbenotmore
in. (mm) lb/1000 lf (kg/m)
⁄4 (19) 277 (0.412)
than 30 ft (9 m). A control joint shall be installed where an
1 ⁄2 (38) 414 (0.616)
expansion joint occurs in the base exterior wall or ceiling. A
2 (50) 506 (0.753)
ceiling height door frame, installed in accordance with the
2 ⁄2 (64) 597 (0.888)
spacing requirements set forth in this section, is not prohibited
6.7.5 Rod and flat (strap) hangers shall be mild steel, zinc from being used as a control joint.
coated or protected with a rust-inhibiting paint. 7.1.5 Where partition assemblies require the installation of
6.7.6 Clips—Devices for attaching framing members to control joints over the head of door frames to relieve stresses
supports or to each other; for attaching lath to framing within the assemblies, such control joints shall be installed in
members; or for securing lath to lath, shall be formed of the following manner:
´1
C841−03(2008)
7.1.5.1 Wherecontroljointsarelocatedattheverticalcenter driven with the crown parallel to the nailing members. The
of the door opening two metal studs shall be installed not more crown shall bear lightly against, but not cut into, the face of the
than ⁄2 in. (12.7 mm) apart over the center of the span at the lath.
head of the frame, with the lath installed so that a vertical joint
7.4 Application of Gypsum Lath to Metal Supports:
occurs between the studs. A prefabricated control j
...
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.
´1
Designation:C841–99 Designation: C 841 – 03(Reapproved 2008)
Standard Specification for
Installation of Interior Lathing and Furring
This standard is issued under the fixed designation C 841; 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.
This standard has been approved for use by agencies of the Department of Defense.
´ NOTE—The units statement in subsection 1.2 was corrected editorially in July 2008.
1. Scope *
1.1 This specification covers the minimum requirements for, and the methods of application of, interior lathing and furring to
receive gypsum plaster applied in accordance with Specification C 842. Other materials are not prohibited from being used
provided that their physical characteristics and durability under conditions of usage are at least equal in performance to those
described.
1.2Thevaluesstatedininch-poundunitsaretoberegardedasthestandard.Themetricvaluesshowninparenthesesareprovided
for information only.
1.2 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.
1.3 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.
1.4 Where a specific degree of sound control is required for plastered assemblies and constructions, details of construction shall
be obtained from reports of sound tests of assemblies that have met the requirements of Test Method E 492.
2. Referenced Documents
2.1 ASTM Standards:
A 641/A 641M Specification for Zinc-Coated (Galvanized) Carbon Steel Wire
C 11 Terminology Relating to Gypsum and Related Building Materials and Systems
C 37/C 37M Specification for Gypsum Lath
C 514 Specification for Nails for the Application of Gypsum Board
C 754 Specification for Installation of Steel Framing Members to Receive Screw-Attached Gypsum Panel Products
C 842 Specification for Application of Interior Gypsum Plaster
C 847 Specification for Metal Lath
C 933 Specification for Welded Wire Lath
C 954 Specification for Steel Drill Screws for theApplication of Gypsum Panel Products or Metal Plaster Bases to Steel Studs
from 0.033 in. (0.84 mm) to 0.112 in. (2.84 mm) in Thickness
C 1002SpecificationforSteelDrillScrewsfortheApplicationofGypsumBoardorMetalPlasterBases SpecificationforSteel
Self-Piercing Tapping Screws for the Application of Gypsum Panel Products or Metal Plaster Bases to Wood Studs or Steel
Studs
C 1007 Specification for Installation of Load Bearing (Transverse and Axial) Steel Studs and Related Accessories
C 1032 Specification for Woven Wire Plaster Base
D 1784Specification for Rigid Poly Vinyl Chloride PVC Compounds and Chlorinated Poly Vinyl Chloride CPVC Compounds
Specification for Rigid Poly(Vinyl Chloride) (PVC) Compounds and Chlorinated Poly(Vinyl Chloride) (CPVC) Compounds
D 3678 Specification for Rigid Poly(Vinyl Chloride) (PVC) Interior-Profile Extrusions
E 492 Test Method for Laboratory Measurement of Impact Sound Transmission Through Floor-Ceiling Assemblies Using the
Tapping Machine
ThisspecificationisunderthejurisdictionofASTMCommitteeC-11C11onGypsumandRelatedBuildingMaterialsandSystems,Systemsandisthedirectresponsibility
of Subcommittee C11.03 on Specifications for the Application of Gypsum and Other Products in Assemblies.
Current edition approved Oct. 10, 1999.May 1, 2008. Published January 2000.July 2008. Originally published as C841–76.approved in 1976. Last previous edition
C841–98.approved in 2003 as C 841 – 03.
Annual Book of ASTM Standards, Vol 01.06.
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*ASummary 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
C 841 – 03 (2008)
2.2 National Association of Architectural Metal Manufacturers Standard
HMMA 840 Installation and Storage of Hollow Metal Doors and Frames
3. Terminology
3.1 Definitions—For definitions relating to ceilings and walls see Terminology C 11.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 base coat, n—the sum of the scratch and brown coats or the total coats in place prior to application of finish coats.
3.2.2 contact ceiling, n—a ceiling in which the lath is attached in direct contact with the construction above, without the use
of main runners or cross furring.
3.2.3 furred ceiling, n—a ceiling in which the furring used for the support of the lath is attached directly to the structural
members of the building.
3.2.4 suspended ceiling, n—a ceiling in which the main runners and cross furring are suspended below the structural members
of the building.
3.2.5 main runners, n—the members that are attached to or suspended from the construction above for the support of cross
furring.
3.2.6 cross furring, n—furring members that are attached at right angles to the underside of the main runners or construction
above for support of the lath.
3.2.7 furring, n—spacer strips fastened to a wall, ceiling, or planar element that create an even surface for the application of
metal plaster bases or gypsum lath.
3.2.8 primary members, n—the members (main runners or structural supports) to which the cross furring is attached.
3.2.9 metal plaster bases, n—expanded metal lath, sheet metal lath, welded or woven wire lath.
3.2.10 face side (gypsum lath), n—the side opposite the paper cover seam laps.
3.2.11 surface transition, n—the change in width of a surface, usually as a result of penetrations (doors, windows) or
architectural demands.
4. Delivery of Materials
4.1 All materials shall be delivered in the original packages, containers, or bundles bearing the brand name and manufacturer’s
(or supplier’s) identification.
5. Storage of Materials
5.1 All materials shall be kept dry, preferably by being stored inside. Where necessary to be stored outside, materials shall be
stacked off the ground, supported on a level platform, and protected from the weather and surface contamination.
5.2 Materials shall be neatly stacked flat with care taken to avoid damage to edges, ends, or surfaces.
6. Materials
6.1 Wire Specification A 641/A 641M, Class 1 coating (galvanized) soft temper.
6.1.1 Tie Wire and Hanger Wire—Zinc-coated (galvanized) soft-annealed steel, or a material having equivalent size, corrosion
resistance and strength. Wire diameters (uncoated) specified herein correspond with United States steel wire gage numbers as
follows:
A
Diameter, in. mm (mm)
0.0348 0.88 No. 20
0.0348 (0.88) No. 20
0.0410 1.04 No. 19
0.0410 (1.04) No. 19
0.0475 1.21 No. 18
0.0475 (1.21) No. 18
0.0540 1.37 No. 17
0.0540 (1.37) No. 17
0.0625 1.59 No. 16
0.0625 (1.59) No. 16
0.0800 2.03 No. 14
0.0800 (2.03) No. 14
0.0915 2.32 No. 13
0.0915 (2.32) No. 13
0.1055 2.68 No. 12
0.1055 (2.68) No. 12
0.1205 3.06 No. 11
0.1205 (3.06) No. 11
Annual Book of ASTM Standards, Vol 04.01.
Available from NAAMM, 8 South Michigan Avenue, Suite 1000, Chicago, IL 60603.
´1
C 841 – 03 (2008)
A
Diameter, in. mm (mm)
0.1350 3.43 No. 10
0.1350 (3.43) No. 10
0.1483 3.77 No. 9
0.1483 (3.77) No. 9
0.1620 4.11 No. 8
0.1620 (4.11) No. 8
_____________
A
Allowable variations in diameter shall be in accordance with tolerances as established in A 641/A 641M.
6.2 Gypsum Lath—Specification C 37.
6.3 Expanded Metal Lath—Specification C 847.
6.4 Wire Lath:
6.4.1 Welded Wire Lath, Specification C 933.
6.4.2 Woven Wire Lath, Specification C 1032.
6.5 Fasteners:
6.5.1 Nails for Attaching Gypsum Lath— Specification C 514. Nail size shall be in accordance with Table 1.
6.5.2 Nails for Attaching Metal Plaster Base—Galvanized roofing nails or common nails. length shall be as specified in 7.
6.5.3 Screws—Specifications C 954 or C 1002.
6.5.3.1 Screws for attaching gypsum lath shall be sized in accordance with Table 1.
6.5.3.2 Screws for attaching metal plaster base shall have a ⁄16 in. (11.1 mm) diameter pan washer head and a 0.120 in. (3.0
mm) diameter shank. The length shall be sufficient enough to allow for the threaded portion of the screw to project not less than
⁄8 in. (9.5 mm) through steel framing when the lath is installed.
6.5.4 Staples—Staples for attaching gypsum lath shall conform to the requirements of Table 1.
6.5.4.1 Staples for attaching metal plaster base shall be 0.062 in. (1.6 mm) diameter, round or flattened steel wire with ⁄4 in.
(19.0 mm) crown. Lengths shall be as specified for individual systems.
6.6 Paper or Other Backing—When used on metal plaster bases, over solid backing, backing shall be securely held in place
by, or attached to the metal plaster base. Metal plaster base shall allow for ⁄4 in. (6.4 mm) self furring. The backing shall permit
embedment of plaster.
6.7 Accessories—Shall be steel, coated, with a protective rust inhibitive coating after fabrication, or fabricated from zinc-coated
(galvanized) steel, aluminum, zinc alloy, or high impact plastic. Plastic accessories shall be nmanufactured in accordance with
Specifcation D 1784 or Specification D 3678. Aluminum accessories shall be clear plastic coated. All accessories shall have
perforated or expanded flanges or clips shaped so as to permit complete imbedment in the plaster, to provide means for secure
alignment, and to secure attachment of the accessory to the underlying surface.Accessories shall be designed for the intended use
and to receive or to permit application of the specified plaster thickness.
6.7.1 Thickness of base material for accessories shall be not less than as shown in the following:
A,B
TABLE 1 Screws, Nails and Staples for Attaching Gypsum Lath to Horizontal and Vertical Wood Supports
Maximum Spacing, in. (mm) Minimum Gage Requirements, in. (mm)
Diameter of
Flat Head or Gage of
Distance Number of Approximate Depth of
Width of Thickness Length of Blued Nails Shank of
Between Attachments Spacing c to c of Support
Lath of Lath Leg or Crown Nails or
Supports per Bearing Attachments Penetration
A
Width of Staples
A
Staples
3 1 3 19
16 (406) ⁄8 (9.5) 16 (406) 4 5 (127) 1 ⁄8 (28.6) ⁄4 (19) ⁄64 (7.5) 13
A A A A
5 7
1 (25.4) ⁄8 (15.9) ⁄16 (11) 16
3 1 1 3 19
24 (610) ⁄8 (9.5) 16 (406) 6 4 ⁄2 (114) 1 ⁄8 (28.6) ⁄4 (19) ⁄64 (7.5) 13
A A A A
5 7
1 (25.4) ⁄8 (15.9) ⁄16 (11) 16
1 1 3 19
16 (406) ⁄2 (12.7) 24 (610) 4 5 (127) 1 ⁄4 (32) ⁄4 (19) ⁄64 (7.5) 13
A A A A
1 5 7
1 ⁄8 (28.6) ⁄8 (15.9) ⁄16 (11) 16
1 1 1 3 19
24 (610) ⁄2 (12.7) 24 (610) 6 4 ⁄2 (114) 1 ⁄4 (32) ⁄4 (19) ⁄64 (7.5) 13 (330)
A A A A
1 5 7
1 ⁄8 (28.6) ⁄8 (15.9) ⁄16 (11) 16
3 1 1 3
48 (1219) ⁄8 (9.5) 16 (406) 8 4 ⁄2 (114) 1 ⁄8 (28.6) ⁄4 (19)
A A
1 5
⁄2 (12.7) 24 (610) 1 (25.4) ⁄8 (15.9)
1 3
1 ⁄4 (32) ⁄4 (19)
A A
1 5
1 ⁄8 (28.6) ⁄8 (15.9)
A
Galvanized staples.
B
Screws for attaching gypsum lath to wood supports shall be Type W as described in Specification C 1002.
´1
C 841 – 03 (2008)
Base Material (mm) Thickness of
Base Material, in.
Uncoated steel/zinc 0.014 (0.36)
PVC 0.030 (0.76)
Aluminum 0.050 (1.27)
6.7.2 Control Joints— Shall be formed by using a single prefabricated member or fabricated by installing casing beads back
to back with a flexible barrier membrane behind casing beads. The separation spacing shall be not less than ⁄8 in. (3.2 mm) or as
required by the anticipated thermal exposure range.
2 2
6.7.3 Cornerite—shall be not less than 1.75 lb/yd (0.85 kg/m ) expanded metal lath, galvanized, or given a protective coating
of rust inhibitive paint after fabrication, or woven or welded fabric not less than 0.041 in. (1.04 mm) thick an weighing not less
2 2
than1.75lb/yd (0.85kg/m ),fabricatedfromgalvanizedwire.Whenshapedforanglereinforcing,corneriteshallhaveoutstanding
legs of not less than 2 in. (50.8 mm).
6.7.4 Channels—Shall be cold-rolled steel, free of rust with a coating of rust inhibitive paint or galvanized. Channels used in
areassubjecttocorrosiveactionofsaltairorothercorrosiveenvironments,shallbehot-dipgalvanized.Weightofthechannelshall
be not less than as shown in the following:
´1
C 841 – 03 (2008)
Size Weight
in. mm lb/1000 lf kg/m
in. (mm) lb/1000 lf kg/m
⁄4 (kg/m)
⁄4 19 300 0.446
⁄4 (19) 277 0.446
1 ⁄2 (0.412)
1 ⁄2 38 475 0.707
1 ⁄2 (38) 414 0.707
(0.616)
2 50 590 0.818
2 (50) 506 0.818
2 ⁄2 (0.753)
2 ⁄2 64 665 0.989(0.888)
2 ⁄2 (64) 597 (0.888)
6.7.5 Rod and flat (strap) hangers shall be mild steel, zinc coated or protected with a rust-inhibiting paint.
6.7.6 Clips—Devices for attaching framing members to supports or to each other; for attaching lath to framing members; or for
securing lath to lath, shall be formed of zinc-coated (galvanized) steel wire or sheet, and of sufficient size and strength to support
the intended load
2 2
6.7.7 Striplath—Shall be not less than 1.75 lb/yd (0.85 kg/m ) expanded metal lath, or woven or welded fabric of not less than
2 2
0.041 in. (1.04 mm) thick weighing not less than 1.75 lb/yd (0.85 kg/m ) fabricated from galvanized steel.
7. Installation
7.1 General Requirements for Application of Lath and Accessories:
7.1.1 Lath shall be installed with the long dimension at right angles to supports, unless otherwise specified.
7.1.2 Corner beads shall be installed to protect all external corners and to establish grounds. Corner beads shall be attached to
the substrate in such a manner as to ensure proper alignment during application of plaster.
7.1.3 Metal accessories shall be installed so that flanges and clips provided for their attachment are covered by the base coat
plaster.
2 2
7.1.4 Control Joints—Shall be installed in ceilings greater than 2500 ft (232 m ) in area and in partition, wall, and wall furring
runs greater than 30 ft (9 m) in length. The distance between ceiling control joints shall not be more than 50 ft (15 m) in either
direction. A control joint shall be installed where the ceiling framing or furrin
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