ASTM C840-23

Standard Specification for Application and Finishing of Gypsum Board

ABSTRACT
This specification covers requirements for the methods of application and finishing of gypsum board. Construction details 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. Gypsum board assembly shall conform to acoustical tests of the specification where sound control is required. Moreover, gypsum assembly shall conform to framing size, fasteners spacing, ventilation, substrate, surface preparation, cutting, and installation application as indicated in the specification. Materials categorized under this specification include: gypsum boards, gypsum wallboards, gypsum backing board and coreboard, water-resistant gypsum backing board, exterior gypsum soffit board, and gypsum ceiling board. Finishing materials include: compounds, joint tape, fasteners, nails, screws, and staples. A fire test of assemblies shall be conducted to determine a fire resistance rating required for gypsum board assembly. Gypsum board shall be cut by scoring and breaking or by sawing, working from the face side. Masonry or concrete walls shall be dry, free of dust, oil, or form release agents, protrusions or voids, or foreign matter that inhibit bond for adhesively applied gypsum board. All materials shall be kept dry. Where gypsum board is stored outside, it shall be off the ground, properly supported on a level platform and fully protected from the weather or direct sunlight exposure.
SCOPE
1.1 This specification covers the minimum requirements for the methods of application and finishing of gypsum board, including related items and accessories to interior walls and ceilings and to exterior soffits.  
1.2 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.  
1.2.1 Where this specification is more stringent (size or thickness of framing: size and spacing of fasteners) than the fire-rated construction, this specification shall govern.  
1.3 Where sound control is required for a gypsum board assembly, details of construction shall be in accordance with reports of acoustical tests of assemblies that have met the required acoustical values.  
1.4 Unheated spaces above gypsum board ceilings shall be properly ventilated (see Appendix X2).  
1.5 The various application systems are located in the following sections:    
I  
Application of Single-ply Gypsum Board to Wood Framing Members  
8  
II  
Application of Two-ply Gypsum Board to Wood Framing Members  
9  
III  
Application of Gypsum Board by Adhesive Nail-on to Wood Framing
Members  
10  
IV  
Semi-solid Gypsum Board Partitions  
11  
V  
Solid Gypsum Board Partitions  
12  
VI  
Application of Gypsum Board with Adhesives to Interior Masonry or
Concrete Walls  
13  
VII  
Application of Gypsum Board to Rigid Foam Insulation  
14  
VIII  
Application of Gypsum Board to Steel Framing and Furring  
15  
IX  
Arches and Bending Radii  
16  
X  
Application of Gypsum Board to Receive Tile by Adhesive Application  
17  
XI  
Application of Exterior Gypsum Soffit Board or Other Gypsum Board for Use in Exterior Soffits  
18  
XII  
Floating Interior Angles  
19  
XIII  
Control (Expansion) Joints  
20  
XIV  
Foil-backed Gypsum Board  
21  
XV  
Application of Vinyl Faced Gypsum Board  
22  
1.6 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.  
1.7 The text of this specification references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as ...

General Information

• Status: Published
• Publication Date: 30-Sep-2023
• 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

Relations

• Replaces: ASTM C840-20 - Standard Specification for Application and Finishing of Gypsum Board
• Effective Date: 01-Oct-2023
• Referred By: ASTM C754-20 - Standard Specification for Installation of Steel Framing Members to Receive Screw-Attached Gypsum Panel Products
• Effective Date: 01-Oct-2023
• Referred By: ASTM C474-15(2020) - Standard Test Methods for Joint Treatment Materials for Gypsum Board Construction
• Effective Date: 01-Oct-2023
• Referred By: ASTM C475/C475M-17(2022) - Standard Specification for Joint Compound and Joint Tape for Finishing Gypsum Board
• Effective Date: 01-Oct-2023
• Referred By: ASTM C1467/C1467M-00(2021) - Standard Specification for Installation of Molded Glass Fiber Reinforced Gypsum Parts
• Effective Date: 01-Oct-2023
• Referred By: ASTM C1546-19 - Standard Guide for Installation of Gypsum Products in Concealed Radiant Ceiling Heating Systems
• Effective Date: 01-Oct-2023
• Referred By: ASTM C1629/C1629M-23 - Standard Classification for Abuse-Resistant Nondecorated Interior Gypsum Panel Products and Fiber-Reinforced Cement Panels
• Effective Date: 01-Oct-2023
• Referred By: ASTM C1396/C1396M-17 - Standard Specification for Gypsum Board
• Effective Date: 01-Oct-2023

Overview

ASTM C840-23: Standard Specification for Application and Finishing of Gypsum Board is the authoritative guide developed by ASTM International for best practices in the installation and finishing of gypsum board in construction projects. This standard covers both interior and select exterior (soffit) applications, ensuring that gypsum board assemblies meet essential criteria for fire resistance, sound control, structural integrity, and aesthetics. The document is widely referenced across the building industry, setting minimum requirements for application methods, finishing systems, materials, and environmental conditions.

Key Topics

• Gypsum Board Types: Includes regular gypsum boards, wallboards, backing boards, water-resistant boards, exterior soffit boards, ceiling boards, foil-backed, and vinyl-faced boards.
• Installation Methods: Details application on wood and steel framing, adhesive set, multi-layer installations, soffits, solid and semi-solid partition systems, and applications over masonry or concrete.
• Finishing Systems: Specifies compounds, joint tapes, fasteners (nails, screws, staples), and accessories required for seamless surface finishing.
• Fire Resistance: Requires compliance with certified fire-resistance reports, laboratory listings, and engineering evaluations for assembly performance.
• Acoustical Requirements: Calls for conformance with acoustical test data where noise control is a design requirement.
• Environmental Conditions: Defines acceptable humidity, temperature, and moisture provisions for board storage, application, and curing.
• Cutting and Preparation: Describes scoring, breaking, and cutting processes, as well as the required substrate and surface preparation for secure installation.
• Ventilation: Identifies the need for proper ventilation in spaces above gypsum board ceilings.

Applications

ASTM C840-23 is essential for a wide range of building construction scenarios, including:

• Residential and Commercial Projects: Guidance applies to both single- and multi-family dwellings, offices, schools, hospitals, and other commercial spaces.
• Interior Walls and Ceilings: Instructs on installation and finishing practices for partition walls, corridor walls, and various ceiling types.
• Exterior Soffits: Extends to the proper use of specific gypsum products in protected exterior soffit applications.
• Fire-rated and Sound-rated Assemblies: Critical for assemblies requiring tested fire resistance or sound-control performance.
• Renovations and Retrofits: Useful for both new installations and upgrades to existing structures in compliance with modern building codes.

Related Standards

To ensure a comprehensive approach to gypsum board application, ASTM C840-23 references or aligns with several other industry standards, including:

• ASTM C1396/C1396M – Specification for Gypsum Board
• ASTM C475/C475M – Specification for Joint Compound and Joint Tape
• ASTM C514 – Specification for Nails for the Application of Gypsum Board
• ASTM C557 – Specification for Adhesives for Fastening Gypsum Wallboard to Wood Framing
• ASTM C754 – Specification for Installation of Steel Framing Members to Receive Screw-Attached Gypsum Panel Products
• ASTM C1002 – Specification for Steel Self-Piercing Tapping Screws for Gypsum Board
• ASTM C1047 – Specification for Accessories for Gypsum Wallboard and Gypsum Veneer Base
• ANSI A108 – Specifications for the Installation of Ceramic Tile

Practical Value

Implementing ASTM C840-23 in your construction projects ensures appropriate handling, application, and finishing of gypsum board for optimal performance and longevity. The standard assists architects, builders, contractors, and code officials by:

• Promoting safety and code compliance for fire and sound requirements
• Ensuring high-quality finishes through best practices in joint treatment and accessory application
• Reducing risk of installation errors that could compromise wall and ceiling systems
• Supporting efficient project planning with clear instructions on spacing, environmental controls, and material selection

For up-to-date installation guidance and to meet regulatory and performance requirements, ASTM C840-23 is an indispensable standard for any construction professional working with gypsum board.

Standards Content (Sample)

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.
Designation: C840 − 23
Standard Specification for
Application and Finishing of Gypsum Board
This standard is issued under the fixed designation C840; 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 U.S. Department of Defense.
1. Scope*
XIV Foil-backed Gypsum Board 21
XV Application of Vinyl Faced Gypsum Board 22
1.1 This specification covers the minimum requirements for
1.6 The values stated in inch-pound units are to be regarded
the methods of application and finishing of gypsum board,
as standard. The values given in parentheses are mathematical
including related items and accessories to interior walls and
conversions to SI units that are provided for information only
ceilings and to exterior soffits.
and are not considered standard.
1.2 Details of construction for a specific assembly to
1.7 The text of this specification references notes and
achieve the required fire resistance shall be obtained from
footnotes which provide explanatory material. These notes and
reports of fire-resistance tests, engineering evaluations, or
footnotes (excluding those in tables and figures) shall not be
listings from recognized fire testing laboratories.
considered as requirements of the specification.
1.2.1 Where this specification is more stringent (size or
1.8 The following precautionary caveat pertains only to
thickness of framing: size and spacing of fasteners) than the
fire-rated construction, this specification shall govern. Sections 6 – 26. This standard does not purport to address all
of the safety concerns, if any, associated with its use. It is the
1.3 Where sound control is required for a gypsum board
responsibility of the user of this standard to establish appro-
assembly, details of construction shall be in accordance with
priate safety, health, and environmental practices and deter-
reports of acoustical tests of assemblies that have met the
mine the applicability of regulatory limitations prior to use.
required acoustical values.
For specific precautionary statements, see 4.1.1, 4.1.2, and
1.4 Unheated spaces above gypsum board ceilings shall be
24.5.
properly ventilated (see Appendix X2).
1.9 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.5 The various application systems are located in the
ization established in the Decision on Principles for the
following sections:
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
I Application of Single-ply Gypsum Board to Wood Framing Members 8
II Application of Two-ply Gypsum Board to Wood Framing Members 9
Barriers to Trade (TBT) Committee.
III Application of Gypsum Board by Adhesive Nail-on to Wood Framing 10
Members
2. Referenced Documents
IV Semi-solid Gypsum Board Partitions 11
V Solid Gypsum Board Partitions 12
2.1 ASTM Standards:
VI Application of Gypsum Board with Adhesives to Interior Masonry or 13
C11 Terminology Relating to Gypsum and Related Building
Concrete Walls
VII Application of Gypsum Board to Rigid Foam Insulation 14
Materials and Systems
VIII Application of Gypsum Board to Steel Framing and Furring 15
C475/C475M Specification for Joint Compound and Joint
IX Arches and Bending Radii 16
Tape for Finishing Gypsum Board
X Application of Gypsum Board to Receive Tile by Adhesive Application 17
XI Application of Exterior Gypsum Soffit Board or Other Gypsum Board 18 C514 Specification for Nails for the Application of Gypsum
for Use in Exterior Soffits
Board
XII Floating Interior Angles 19
C557 Specification for Adhesives for Fastening Gypsum
XIII Control (Expansion) Joints 20
Wallboard to Wood Framing
C645 Specification for Nonstructural Steel Framing Mem-
bers
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. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2023. Published December 2023. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1979. Last previous edition approved in 2020 as C840 – 20. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/C0840-23. 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
C840 − 23
C754 Specification for Installation of Steel Framing Mem- 3.2.6 finish(ing), v—the act of concealing joints with joint
bers to Receive Screw-Attached Gypsum Panel Products compound and tape; concealing fastener heads and edges or
C920 Specification for Elastomeric Joint Sealants flanges of accessories with joint compound.
C954 Specification for Steel Drill Screws for the Application
3.2.7 flange, n—that part of an accessory extending over the
of Gypsum Panel Products or Metal Plaster Bases to Steel
face of the gypsum board intended to become a part of the
Studs from 0.033 in. (0.84 mm) to 0.112 in. (2.84 mm) in
monolithic plane of the prepared surface.
Thickness
3.2.8 joint photographing, n—a condition where the fin-
C955 Specification for Cold-Formed Steel Structural Fram-
ished joint areas are visible after final decoration.
ing Members
3.2.9 joint treatment, n—application of joint tape and com-
C1002 Specification for Steel Self-Piercing Tapping Screws
pound to the joint between gypsum boards.
for Application of Gypsum Panel Products or Metal
Plaster Bases to Wood Studs or Steel Studs
3.2.10 laminating compound, n—a material used to adhere
C1007 Specification for Installation of Load Bearing (Trans-
gypsum board to gypsum board or other monolithic materials.
verse and Axial) Steel Studs and Related Accessories
3.2.11 moderate contact, n—the edges and ends are butted
C1047 Specification for Accessories for Gypsum Wallboard
at joints but not forced together.
and Gypsum Veneer Base
3.2.11.1 Discussion—Small gaps not greater than ⁄4 in.
C1396/C1396M Specification for Gypsum Board
(6 mm) are acceptable (see 7.4).
C1546 Guide for Installation of Gypsum Products in Con-
3.2.12 parallel or vertical application, n—gypsum board
cealed Radiant Ceiling Heating Systems
applied with the edges parallel to the framing member to which
E2634 Specification for Flat Wall Insulating Concrete Form
it is attached.
(ICF) Systems
3.2.13 perpendicular or horizontal application, n—gypsum
2.2 U.S. Department of Commerce Publication:
board application with the edges applied at right angles to the
PS20 American Softwood Lumber Standard
framing member to which it is attached.
2.3 ANSI Standards:
ANSI A108 Specifications for the Installation of Ceramic
3.2.14 ready-mix type, n—a factory-prepared compound
Tile
ready to be used without the addition of water.
ANSI A136.1 Specifications for Organic Adhesives for
3.2.15 setting type, n—a joint compound that hardens by a
Installation of Ceramic Tile, Type I and Type II
chemical reaction and increases in strength through drying.
2.4 AISI Standards:
3.2.16 skim coat, n—either a thin coat joint compound
S220 North American Standard for Cold-Formed Steel
applied at a trowel consistency or a material manufactured
Framing – Nonstructural Members
specifically for this purpose, applied in accordance with
S240 North American Standard for Cold-Formed Steel
manufacturer’s recommendations over the entire surface.
Structural Framing
3.2.16.1 Discussion—A skim coat is essentially a film of
joint compound and is not applied at a readily measurable
3. Terminology
thickness. There is no specific mil thickness that constitutes a
3.1 Definitions—Definitions shall be in accordance with
proper skim coat (see Appendix X7).
Terminology C11.
3.2.17 spotted, adj—a fastener head that has been covered
3.2 Definitions of Terms Specific to This Standard:
with joint compound.
3.2.1 critical lighting, n—a condition where interior sur-
3.2.18 treated joint, n—a joint between gypsum boards that
faces are flooded by natural or artificial lighting at an oblique
is reinforced with tape and joint compound or covered by strip
angle.
moldings.
3.2.2 decoration, n—a material or materials designed to
conceal or protect the surface of the gypsum board (see
4. Environmental Conditions
Appendix X3).
4.1 Application of Gypsum Board, Joint Treatment
3.2.3 dry type, n—a compound in powder form to be mixed
Materials, and Adhesives—Room temperature shall be main-
with water before use.
tained at not less than 40 °F (4 °C) during application of
3.2.4 drying type, n—a joint compound that hardens due to
gypsum board except when adhesive is used for the attachment
evaporation.
of gypsum board. For the bonding of adhesive, joint treatment,
3.2.5 face panel, n—outside ply of multiple layer gypsum
texturing, and decoration, the room temperature shall be
board assemblies.
maintained at not less than 50 °F (10 °C) for 48 h prior to
application and continuously thereafter until occupancy. See
X7.7 for additional detail regarding environmental control
Available from U.S. Government Printing Office, Superintendent of
during the installation and finishing process.
Documents, 732 N. Capitol St., NW, Washington, DC 20401-0001, http://
www.access.gpo.gov.
4.1.1 When a temporary heat source is used, the temperature
Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
shall not exceed 95 °F (35 °C) in any given room or area.
4th Floor, New York, NY 10036, http://www.ansi.org.
4.1.2 Adequate ventilation shall be maintained in the work-
Available from American Iron and Steel Institute (AISI), 25 Massachusetts
Ave., NW, Suite 800, Washington, DC 20001, http://www.steel.org. ing area during installation and curing period.
C840 − 23
4.1.2.1 When portable gas or kerosene heaters are used, the 5.8.3 Staples—No. 16 USS gauge flattened galvanized wire
extra humidity that they produce shall be removed by ventila- staples with ⁄16 in. (11 mm) wide crown outside measurement.
tion or mechanical dehumidification. Legs shall have divergent points.
4.2 Gypsum board shall be protected from direct exposure
NOTE 2—Use only for the base ply of two-ply gypsum board applica-
to rain, snow, sunlight, or other excessive weather conditions. tion.
5.8.3.1 Staples for use with pressure treated lumber shall be
NOTE 1—Where manufacturers’ recommendations differ from the
above, follow their recommendations.
compatible with the preservative treated and fire retardant
treated lumber.
4.3 Ready-mixed joint compounds shall be protected from
freezing, exposure to extreme heat, and direct sunlight.
5.9 Adhesives:
5.9.1 Fastening Gypsum Board to Wood Framing—See
5. Materials and Manufacture
Specification C557.
5.1 Gypsum Boards—A family of gypsum sheet products as 5.9.2 Fastening Gypsum Board to Steel Framing—As speci-
defined in Terminology C11. fied by the manufacturer.
5.1.1 Type X (Special Fire-resistant) Gypsum Wallboard, 5.9.3 Laminating Gypsum Board to Gypsum Board—
Gypsum Backing Board, Water-resistant Gypsum Backing
Laminating compounds, taping compound, or adhesive shall be
Board, or Exterior Gypsum Soffıt Board—Gypsum board that as specified by the manufacturer.
provides a greater degree of fire resistance than regular gypsum
5.10 Framing Members:
board as defined in Specification C1396/C1396M.
5.10.1 Wood framing members shall conform to PS20,
5.1.2 Foil-backed Gypsum Wallboard or Gypsum Backing
American Softwood Lumber Standards. The surface to which
Board—Regular or Type X gypsum board with foil laminated
abutting edges or ends are attached shall be not less than 1 ⁄2 in.
to the back surface. The foil is a vapor retarder.
(38 mm) wide. For internal corners or angles, the bearing
5.1.3 Predecorated Gypsum Board—Gypsum board with a
surface shall not be less than ⁄4 in. (19 mm).
decorative wallcovering or coating applied in-plant by the
5.10.2 Steel Studs, Furring Channels, and Runners:
gypsum board manufacturer.
5.10.2.1 Non-load-bearing (see Specification C645 or AISI
5.2 Gypsum Wallboard—See Specification C1396/C1396M.
S220).
5.10.2.2 Load-bearing (see Specification C955 or AISI
5.3 Gypsum Backing Board and Coreboard—See Specifica-
tion C1396/C1396M. S240).
5.10.3 Gypsum Studs—Specification C1396/C1396M, not
5.4 Water-resistant Gypsum Backing Board—See Specifica-
less than 1 in. (25 mm) thick by 6 in. (150 mm) wide. Studs
tion C1396/C1396M.
shall be either solid or laminated.
5.5 Exterior Gypsum Soffıt Board—See Specification
5.11 Accessories—See Specification C1047.
C1396/C1396M.
5.12 Water—Water shall be clean, fresh, and potable (suit-
5.6 Gypsum Ceiling Board—See Specification C1396/
able for domestic consumption).
C1396M.
5.13 Face Panels—Face panels shall be ⁄2 in. (12.7 mm),
5.7 Finishing Materials:
⁄8 in. (15.9 mm), or multiple laminations of regular or Type X
5.7.1 Compounds—Taping compound, finishing compound,
gypsum board.
and all-purpose compound shall meet the requirements of
Specification C475/C475M. 3
5.14 Core Board—Core board shall be ⁄4 in. or 1 in.
5.7.2 Mix compounds in accordance with the manufactur-
(19 mm or 25.4 mm) either single thickness or multiple layers
ers’ directions.
to the required 25 mm thickness.
5.7.3 Joint Tape—See Specification C475/C475M.
6. Substrate, Surface Preparation
5.8 Fasteners:
5.8.1 Nails—See Specification C514.
6.1 The attachment surface of any framing member shall not
5.8.1.1 Nails for use with pressure treated lumber shall be
vary more than ⁄8 in. (3 mm) from the plane of the faces of
compatible with the preservative treated and fire retardant
adjacent framing members.
treated lumber.
6.2 Wood framing shall be as straight and true as possible.
5.8.2 Screws:
Wood framing shall be securely attached following acceptable
5.8.2.1 See Specification C1002 for screws for fastening
engineering practices and as required for the intended design.
gypsum board to wood members, steel members less than
0.033 in. (0.84 mm) in thickness, and to gypsum board.
NOTE 3—For installation of wood framing, see Appendix X4.
5.8.2.2 See Specifications C754 and C954 for screws for
6.3 Metal framing members shall be of the proper size and
fastening gypsum board to steel members from 0.033 in. to
design for their intended use and shall be installed in accor-
0.112 in. (0.84 mm to 2.84 mm) in thickness.
dance with Specifications C754 or C1007 as required.
5.8.2.3 Screws for use with pressure treated lumber shall be
compatible with the preservative treated and fire retardant 6.4 Where used as an alternative to framing, backing, or
treated lumber. blocking, specially designed corner clips and edge clips shall
C840 − 23
be applied in accordance with their listings or approvals and 7.1.3.1 Gypsum board applied to walls shall be applied with
the clip manufacturer’s recommendations. the bottom edge spaced not less than ⁄4 in. (6 mm) above the
floor.
6.5 Devices or items attached to framing members, includ-
7.1.4 Where used at edges or ends, fasteners shall be spaced
ing the fasteners used to attach such devices or items, shall not
not more than 1 in. (25 mm) from edges and not less than ⁄8 in.
protrude more than ⁄8 in. (3 mm) beyond the surface to which
(10 mm) from edges and ends of gypsum board (except where
the gypsum board is to be applied.
floating angles are used). Perimeter fastening into the partition
6.6 Masonry or concrete walls shall be dry, free of dust, oil, plate or sole at the top and bottom shall not be required except
or form release agents, protrusions or voids, or foreign matter where the fire ratings, structural performance, or other special
that inhibit bond for adhesively applied gypsum board. conditions require such fastening. While driving the fasteners,
the gypsum board shall be held in firm contact with the
6.7 All framing members and substrate shall be installed so
underlying support. Application of fasteners shall proceed from
that after the gypsum board has been applied, the finished
the center or field of the gypsum board to the ends and edges.
surface will be in an even plane.
7.1.5 Nails shall be driven with the heads slightly below the
6.8 Gypsum board shall be kept free of any dirt, oil, or other surface of the gypsum board, avoiding damage to the face and
core of the board, such as breaking the paper or fracturing the
foreign matter that cause a lack of bond. Foreign matter shall
be removed. core.
7.1.5.1 Length of nails shall be as shown in Table 1.
6.9 All dents or gouges on the face of the gypsum board
7.1.6 Screws shall be driven to provide screw head penetra-
shall be brought up to a smooth level plane with the surface of
tion just below the gypsum board surface without breaking the
the board.
surface paper of the gypsum board and without spinout.
6.10 Mechanical fasteners shall be set below the plane of
NOTE 4—Refer to Appendix X8 for guidance on some of the potential
the surface of the board.
ways to minimize screw spinout in framing.
6.11 All joints shall be true and even. 7.1.6.1 Length of screws shall be as shown in Table 1.
7.1.7 Staples shall be driven with the crown parallel to the
6.12 All gypsum board shall be tight against the framing
framing members, in such a manner that the crown bears
member or substrate.
tightly against the gypsum board without cutting into the face
6.13 Deflection at design load of horizontal (ceiling) fram- paper.
ing members supporting gypsum board shall be not more than 7.1.7.1 Staple attachment shall be restricted to the base plies
L/240 of the span. only of gypsum board in a multi-ply system.
7.1.7.2 Length of staples shall be as shown in Table 1.
7.1.8 The gypsum board shall be kept tight against the
7. Application of Gypsum Board
framing.
7.1 General:
7.1.9 The external corners shall be protected with a metal
7.1.1 Method of Cutting and Installation—Gypsum board
corner bead or other suitable type of corner protection (see
shall be cut by scoring and breaking or by sawing, working
Specification C1047) that shall be attached to supporting
from the face side. When cutting by scoring, the face paper
construction with fasteners or a crimping tool nominally 6 in.
shall be cut with a sharp knife or other suitable tool. Gypsum
(150 mm) on centers (see Section 3 and Fig. 1), or with an
board shall be broken by snapping the gypsum board in the
adhesive manufactured especially for this purpose. For paper
reverse direction, or cut the back paper with a knife or suitable
tool.
TABLE 1 Fastener Length for Gypsum Board Application to
7.1.1.1 When cutting gypsum panels composed of two or A
Wood Framing
more layers of gypsum board laminated together, both sides
Minimum Minimum
Gypsum Board Minimum Nail
D
shall be scored deeply and then broken by snapping the Screw Staple
B C
Thickness Length
Length
Length
gypsum board in either direction or by cutting with a hand or in. (mm) in. (mm)
in. (mm)
in. (mm)
power tool. E E E
⁄4 (6.4)
3 1
⁄8 (9.5) 1 ⁄4 (32) 1 (25) 1 (25)
7.1.1.2 When cutting gypsum panels having an attached
1 3 1 1
⁄2 (12.7) 1 ⁄8 (35) 1 ⁄8 (28) 1 ⁄8 (28)
laminate, the laminate side shall be scored or cut with a knife,
5 1 1 1
⁄8 (15.9) 1 ⁄2 (38) 1 ⁄4 (32) 1 ⁄4 (32)
or the panel shall be cut with a hand or power tool.
A
Where fire resistance is required for gypsum board systems, fasteners of the
7.1.2 Cut edges and ends of the gypsum board shall be same or larger length, shank diameter, and head bearing area as those described
in the fire-rated design shall be used.
smoothed to obtain neat joints when installed. Holes for pipes,
B
For other thicknesses, for multi-layer applications, or for application over rigid
fixtures, or other small openings shall be scored on the back
foam insulation, fasteners shall be of sufficient length to penetrate framing not less
7 5 5
and the face in outline before removal or cut out with a saw or than ⁄8 in. (22 mm) for nails, ⁄8 in. (16 mm) for screws, and ⁄8 in. (15 mm) for
staples.
special tool designed for this purpose. Where gypsum board
C
The maximum penetration for nails shall not exceed 1 ⁄4 in. (32 mm).
D
meets projecting surfaces, it shall be scribed and cut neatly.
Staple attachment is restricted to base layers of multi-layer systems only. See
7.1.7.1.
7.1.3 When gypsum board is to be applied to both ceiling
E
For application over existing solid surfaces or in multi-layer applications only. See
and walls, the gypsum board shall be applied first to the ceiling
footnote B above for required fastener length.
and then to the walls.
C840 − 23
NOTE 1—All dimensions are in inch-pound units.
FIG. 1 Accessories
A
TABLE 2 Maximum Framing Spacing for Single-ply Construction
faced corner bead with paper wings for attachment, attach with
Maximum
all-purpose or taping joint compound meeting the requirements
Single-ply Framing
of Specification C475/C475M.
Gypsum Board Members On
B
Application
Thickness, in. Centers
7.2 Gypsum board shall not be used where it will be
(mm) Spacing, in.
exposed to temperatures more than 125 °F (52 °C) for extended
(mm)
periods of time.
Ceilings:
3 C
⁄8 (9.5) perpendicular 16 (406)
7.3 Gypsum board joints shall be located so that no joint
⁄2 (12.7) parallel 16 (406)
⁄8 (15.9) parallel 16 (406)
will align with the edge of an opening unless control joints are
⁄2 (12.7) perpendicular 24 (610)
to be installed at these locations.
⁄8 (15.9) perpendicular 24 (610)
Sidewalls:
7.4 Joints between gypsum boards shall be constructed with
⁄8 (9.5) perpendicular or parallel 16 (406)
the gypsum board edges in moderate contact.
⁄2 (12.7) perpendicular 24 (610)
or or
7.5 Joints shall be staggered, and joints on opposite sides of
⁄8 (15.9) parallel
a partition shall not occur on the same stud.
A
Gypsum board ceilings to receive hand or spray-applied water-based texture
7.6 Gypsum board used in building construction shall be not material shall be applied perpendicular to framing and shall be either (i) ⁄2 in.
(12.7 mm) Gypsum Ceiling Board (see Specification C1396/C1396M) applied to
less than 8 in. (200 mm) from the finished grade in fully
framing not more than 24 in. (610 mm) on center, or (ii) other gypsum boards not
weather and water protected siding systems, and not less than 1
less than ⁄2 in. (12.7 mm) thick for 16 in. (406 mm) on center framing and not less
12 in. (300 mm) from the ground within properly drained and than ⁄8 in. (15.9 mm) thick for 24 in. (610 mm) on center framing.
B
Nails for gypsum board applied over existing surfaces shall have a flat head and
ventilated crawl spaces. Where ground moisture or humidity is
diamond point, and shall penetrate not less than ⁄8 in. (22 mm), nor more than
extreme or continuous, or both, the crawl space ground surface 1
1 ⁄4 in. (32 mm) into the framing member.
C
⁄8 in. (9.5 mm) single-ply gypsum board shall not be applied to ceilings where
shall be covered with a vapor barrier.
the gypsum board supports insulation.
8. System I—Application of Single-ply Gypsum Board to
Wood Framing Members
8.1 The maximum spacing for framing members for single-
ply gypsum board assembly shall not exceed those shown in 8.1.1 The ⁄4 in. (6.4 mm) thick gypsum board shall not be
Table 2. used in single-ply applications on either walls or ceilings.
C840 − 23
8.2 In single-ply installation, all ends and edges of gypsum 8.4.2 Single Nailing—Nails shall be spaced a maximum of
board shall occur over framing members or other solid backing 7 in. (175 mm) on centers on ceilings, and a maximum of 8 in.
except where treated joints occur at right angles to framing or
(200 mm) on centers on walls (see Fig. 2).
furring members.
8.4.3 Double Nailing—Nails shall be spaced as shown in
Fig. 3 and driven as follows:
8.3 End joints shall be staggered and joints on opposite
sides of a partition shall be arranged to occur on alternate
8.4.3.1 Starting at the center of the gypsum board, nails
framing members.
shall be applied as shown in solid dots in row 1, then rows 2
and 2A, 3 and 3A, 4 and 4A, always nailing from center to
8.4 Application using nails.
edges of sheet. The gypsum board shall be kept tight against
8.4.1 Where a specific degree of fire resistance is required
the framing.
for gypsum board assemblies, nails of the same length, shank
diameter, and head bearing area, as those described in the fire 8.4.3.2 Second nails, shown by circles, shall be applied in
test report, shall be used. the same manner as the first nails, also starting at row 1.
FIG. 2 Single Nailing
C840 − 23
FIG. 3 Double Nailing
8.4.3.3 As an alternative procedure, the second nail shall be 9.2 The fastener length for the base ply of gypsum board
applied immediately after all nails in each row are driven in shall be as indicated in Table 1.
accordance with 8.4.3.2.
9.2.1 Base layer end joints parallel to and on the same side
8.4.3.4 Single nailing shall be used on the perimeter of the of framing members shall be staggered between alternate
gypsum board, unless otherwise specified.
courses of gypsum board and from base layer joints on the
8.4.3.5 Nails shall be inspected for compliance with 7.1.5 opposite side of the framing members.
after the second nails have been set.
9.2.2 Base layer edge joints parallel to framing members
shall be staggered on opposite sides of the framing members.
8.5 Spacing of Screws—Screws shall be spaced not more
than 12 in. (300 mm) on centers along framing members for
9.3 When adhesive is not used between the plies, the two
ceilings and 16 in. (406 mm) on centers for walls where the
plies of gypsum board shall be applied as indicated in Tables 3
framing members are 16 in. (406 mm) on centers. Screws shall
and 5. The face ply shall be applied with the number of nails
be spaced not more than 12 in. (300 mm) on centers along
or screws required for normal single-ply application. Fastener
framing members for ceilings and walls where the framing
length for face ply application shall be as indicated in foot-
members are 24 in. (610 mm) on centers.
note B of Table 1. Face ply joints that are parallel to framing
8.5.1 When using a combination of fasteners consisting of
shall fall over framing members and be offset from the base ply
nails along the perimeter and screws in the field of the gypsum
joints when two plies of gypsum board are parallel.
board, the spacing between a nail and an adjacent screw shall
9.4 When an adhesive is used between the plies (laminated
be not more than the spacing specified for screws in 8.5.
face ply), the two plies shall be applied as indicated in Tables
4 and 5. If the two plies are applied in parallel direction, the
9. System II—Application of Two-ply Gypsum Board to
joints in the face ply shall be offset from the joints in the base
Wood Framing Members
ply.
9.1 The maximum spacings for framing members for two-
9.4.1 Joints in the face ply need not occur over the framing
ply gypsum board assemblies shall not exceed those shown in
members. The adhesive used between the two plies of gypsum
Tables 3 and 4.
board shall be uniformly applied over the back surface of the
NOTE 5—See Section 2 for adhesive application method. face ply of the gypsum board before it is erected or to the face
A
TABLE 3 Maximum Framing Spacing for Two-ply Assemblies, Fasteners Only, No Adhesive Between Plies
Gypsum Board Thickness,
Maximum On Centers
Application Direction
in. (mm)
Spacing of Framing,
in. (mm)
Base Ply Face Ply Base Ply Face Ply
Ceilings:
1 3 1
⁄4 (6.4) ⁄8 (9.5) or ⁄2 (12.7) perpendicular perpendicular 16 (406)
3 3 1
⁄8 (9.5) ⁄8 (9.5) or ⁄2 (12.7) perpendicular perpendicular 16 (406)
1 3 1
⁄2 (12.7) ⁄8 (9.5) or ⁄2 (12.7) parallel perpendicular 16 (406)
1 1 5
⁄2 (12.7) ⁄2 (12.7) or ⁄8 (15.9) perpendicular perpendicular 24 (610)
B
5 1 5
⁄8 (15.9) ⁄2 (12.7) or ⁄8 (15.9) perpendicular perpendicular 24 (610)
Walls:
1 1 3 1
⁄4 (6.4) ⁄4 (6.4) or ⁄8 (9.5) or ⁄2 (12.7) perpendicular or parallel perpendicular or parallel 16 (406)
3 1 3
⁄8 (9.5) ⁄4 (6.4) or ⁄8 (9.5) perpendicular or parallel perpendicular or parallel 16 (406)
1 1 3 1
⁄2 (12.7) ⁄4 (6.4) or ⁄8 (9.5) or ⁄2 (12.7) perpendicular or parallel perpendicular or parallel 24 (610)
5 1 3 1 5
⁄8 (15.9) ⁄4 (6.4) or ⁄8 (9.5) or ⁄2 (12.7) or ⁄8 (15.9) perpendicular or parallel perpendicular or parallel 24 (610)
A
Gypsum board ceilings to receive hand or spray-applied water-based texture material shall be applied perpendicular to framing and shall be either (i) ⁄2 in. (12.7 mm)
Gypsum Ceiling Board (see Specification C1396/C1396M) applied to framing not more than 24 in. (610 mm) on center, or (ii) other gypsum boards not less than ⁄2 in.
(12.7 mm) thick for 16 in. (406 mm) on center framing and not less than ⁄8 in. (15.9 mm) thick for 24 in. (610 mm) on center framing.
B
⁄8 in. (15.9 mm) board shall be permitted to be applied perpendicularly at 16 in. (406 mm) spacing.
C840 − 23
A
TABLE 4 Maximum Framing Spacing for Two-ply Assembly Fasteners with Adhesive Between Plies
Gypsum Board Thickness,
Maximum On
Application Direction
in. (mm)
Centers Spacing of
Framing, in. (mm)
Base Ply Face Ply Base Ply Face Ply
Ceilings:
1 1 3 1
⁄4 (6.4) ⁄4 (6.4) or ⁄8 (9.5) or ⁄2 (12.7) perpendicular perpendicular 16 (406)
3 1 3 1
⁄8 (9.5) ⁄4 (6.4) or ⁄8 (9.5) or ⁄2 (12.7) perpendicular perpendicular 16 (406)
1 1 3 1
⁄2 (12.7) ⁄4 (6.4) or ⁄8 (9.5) or ⁄2 (12.7) parallel perpendicular 16 (406)
1 1 1 5
⁄2 (12.7) ⁄4 (6.4) or ⁄2 (12.7) or ⁄8 (15.9) perpendicular perpendicular 24 (610)
5 1 1 5
⁄8 (15.9) ⁄4 (6.4) or ⁄2 (12.7) or ⁄8 (15.9) perpendicular perpendicular 24 (610)
Walls:
1 1 3 1
⁄4 (6.4) ⁄4 (6.4) or ⁄8 (9.5) or ⁄2 (12.7) perpendicular or parallel perpendicular or parallel 16 (406)
3 1 3
⁄8 (9.5) ⁄4 (6.4) or ⁄8 (9.5) perpendicular or parallel perpendicular or parallel 16 (406)
1 1 3 1
⁄2 (12.7) ⁄4 (6.4) or ⁄8 (9.5) or ⁄2 (12.7) perpendicular or parallel perpendicular or parallel 24 (610)
5 1 1 5
⁄8 (15.9) ⁄4 (6.4) or ⁄2 (12.7) or ⁄8 (15.9) perpendicular or parallel perpendicular or parallel 24 (610)
A
Adhesive between plies shall be dried or cured prior to joint treatment application.
TABLE 5 Base Layer Fastener Spacing for Multi-layer Gypsum Board Application
Base Layer Base Layer Base Layer
Nail Spacing Screw Spacing Staple Spacing
in. (mm) in. (mm) in. (mm)
Where Face Where Face Where Face
Framing Where Face Layer is Where Face Layer is Where Face Layer is
Spacing Layer is Mechanically Layer is Mechanically Layer is Mechanically
Location in. (mm) Laminated Attached Laminated Attached Laminated Attached
Walls 16 (406) 8 (200) 24 (600) 16 (400) 24 (600) 7 (175) 16 (400)
24 (610) 8 (200) 24 (600) 12 (300) 24 (600) 7 (175) 16 (400)
Ceilings 16 (406) 7 (175) 16 (400) 12 (300) 24 (600) 7 (175) 16 (400)
24 (610) 7 (175) 16 (400) 12 (300) 24 (600) 7 (175) 16 (400)
surface of the base ply. The face ply of gypsum board shall be multi-layer systems shall not be required to be finished unless
placed in position and fastened with nails or screws to hold required for appearance or decoration or as required for fire
gypsum board in place until the adhesive develops a bond. resistance.
9.4.2 Permanent fasteners shall be used around the perim-
eter 12 in. (300 mm) on centers and 16 in. (400 mm) on centers
10. System III—Application of Gypsum Board by
along framing members for the face ply of gypsum board Adhesive Nail-on to Wood Framing Members
applied on ceilings.
10.1 Except as herein modified, application shall be in
9.4.3 In place of nails and screws, the face ply of gypsum
conformance with Section 8.
board applied on walls shall be held in position by shoring with
10.2 Surfaces of gypsum board and framing to receive the
props and headers, or other temporary support to ensure a
adhesive shall be free of dust, dirt, grease, or any other foreign
pressure for bonding. Permanent fasteners shall be used on top
matter that cause bond loss. Foreign matter shall be removed.
and bottom of wall not more than 16 in. (400 mm) on centers.
Nails or screws used to hold the gypsum board face ply shall
10.3 A bead of adhesive ⁄8 in. (10 mm) in diameter shall be
be left in place and finished in the same manner as for
applied to the face of all wood framing members, except plates,
single-ply gypsum board application (see Section 10).
that support the gypsum board. The adhesive shall be spread to
9.5 Base layer joints and fasteners shall not be required to an average width of ⁄4 in. (20 mm) and an average thickness of
be taped or finished. Face layer joints and fasteners in ⁄16 in. (2 mm). See Fig. 4 for application patterns.
FIG. 4 Adhesive Application Patterns
C840 − 23
10.3.1 Where a joining of two adjacent pieces of gypsum 11.1.8 Type G screws shall be used to ensure a continuous
board occurs on a framing member, two parallel beads of bond between face panels and studs, and shall be spaced not
adhesive shall be applied, one near each edge of the framing more than 36 in. (900 mm) on centers.
member. 11.1.9 Openings or changes in direction of partitions shall
be reinforced with additional studs laminated in place at the
10.4 Adhesive shall be applied to no greater area than can
following locations:
be covered with gypsum board within the “open time.”
11.1.9.1 External Corners—Between the face panels in the
NOTE 6—“Open time” is the time period available for working with
corner opposite vertical runners.
certain adhesives before they set in accordance with the adhesive
11.1.9.2 Abutting Walls—Between the face panels of a
manufacturer’s specification.
partition to reinforce junction of an abutting wall.
10.5 Fastener Spacing:
11.1.9.3 Door Openings—Locate a vertical stud within 3 in.
10.5.1 If the properties of the adhesive ensure bridging
(75 mm) of door frame for reinforcement, and place a stud
between the gypsum board and the wood framing, nailing shall
horizontally over the door header.
not be required in the field of the board for walls. In such cases,
perimeter nailing, 16 in. (400 mm) on centers, shall be
12. System V—Solid Gypsum Board Partitions
required.
12.1 Non-load-bearing solid partition consisting of gypsum
10.5.2 When the properties of the adhesive are such that
coreboard faced on each side with gypsum board panels.
there is no positive bridging between the gypsum board and the
wood framing, either temporary field nailing or temporary
12.2 Installation:
bracing shall be used to ensure contact between the gypsum
12.2.1 Floor and ceiling runners shall be installed according
board, the adhesive, and the wood framing, until the adhesive
to the layout and shall be secured not more than 24 in.
develops a bond.
(610 mm) on centers. Vertical runners shall be installed where
10.5.3 Unless specified otherwise by the adhesive
specified in 11.1.1.
manufacturer, fastener spacing shall be in accordance with
12.2.2 For partitions located parallel to and between ceiling
Table 6.
members, steel or wood blocking not more than 24 in.
(610 mm) on centers shall be provided to fasten ceiling runners
11. System IV—Semi-solid Gypsum Board Partitions
prior to erection of ceiling.
12.2.3 Face panels shall be attached to runners at not more
11.1 Installation:
than 24 in. (610 mm) on centers.
11.1.1 Runners or studs shall be installed where required to
12.2.4 Coreboard shall be installed prior to the installation
provide support at exterior walls, partition junctions, terminals,
external corners, door frames, and at other locations. of the face panel. Coreboard shall be attached not more than
24 in. (610 mm) on centers to the steel angles when steel
11.1.2 The gypsum board face panels and studs shall be
positioned vertically. angles are used as runners. When steel channels are used as
runners to secure coreboard, attachment shall not be required.
11.1.3 The gypsum studs shall be laminated to face panels
not more than 24 in. (610 mm) on centers and located at face
NOTE 7—Combinations of wood and steel channels or angles will vary
panel vertical joints and at vertical centerline of panel.
the installation procedure.
11.1.4 Gypsum studs shall be laminated to face panels prior
12.2.5 The adhesive shall be applied to the back surface of
to erection or as erection of partition proceeds. A starter face
the face panels or the face of the coreboard as described for
panel shall be erected vertically at an intersecting wall. The
two-ply gypsum board construction (see Section 9).
starter panel shall be plumb and secured to the floor, the
12.2.6 The face panels shall be laminated to the core with
ceiling, and the vertical runners.
sufficient pressure to ensure bonding. The joints of the face
11.1.5 The next face panel adjacent to the starter panel shall
panels and core shall be staggered. To ensure the bond between
be erected by butting its edge and end firmly to the starter panel
face panels and core, fasteners shall be permitted.
and the ceiling. Erection of the face panels shall continue by
laminating exposed faces of gypsum studs as work progresses.
13. System VI—Application of Gypsum Board with
11.1.6 Openings in partitions for doors and electrical outlets
Adhesive to Interior Masonry or Concrete Walls
shall be carefully and accurately marked and cut.
11.1.7 Laminating compounds or adhesives shall be of a 13.1 When applying gypsum board to monolithic concrete,
consistency and volume that will cover approximately three- brick, or concrete block, the adhesive shall be applied directly
fourths of the stud surface after lamination. to the back of the gypsum board or on the wall in continuous
TABLE 6 Fastener Spacing with Adhesive or Mastic Application and Supplemental Fastening
Framing Member Partitions Load Bearing, Partitions Nonload
Ceilings, in. (mm)
Spacing, in. (mm) in. (mm) Bearing, in. (mm)
On Centers Nail Screw Nail Screw Nail Screw
16 (406) 16 (400) 16 (400) 16 (400) 24 (600) 24 (600) 24 (600)
24 (610) 12 (300) 16 (400) 12 (300) 16 (400) 16 (400) 24 (600)
C840 − 23
beads not more than 12 in. (300 mm) on centers or daubs 2 for single-ply gypsum board and as specified in Tables 3 and
spaced not more than 12 in. (300 mm) on centers each way. 4 for two-ply gypsum board.
13.1.1 Beads shall be not less than ⁄8 in. (10 mm) in 15.2.1 Installation of steel framing shall be in accordance
diameter to provide a continuous bond between the gypsum with Specifications C754 or C1007.
board and the wall surface.
15.3 Screw Spacing:
13.1.2 Daubs shall be 2 in. to 3 in. (50 mm to 75 mm) in
15.3.1 Screw spacing for single-ply gypsum board and face
diameter.
ply of two-ply gypsum board with no adhesive shall be in
13.2 The gypsum board shall be positioned ⁄8 in. (3 mm) accordance with 8.5.
from the floor and provide a tight fit at abutting edges or ends. 15.3.2 Screw spacing for parallel applied base-ply of two-
The gypsum board shall not be slid on the adhesive. Mechani- ply gypsum board over steel framing with no adhesive between
cal fasteners, or temporary bracing, shall be used to support the plies shall be not more than 12 in. (300 mm) on centers
gypsum board until adhesive sets. along the edges of the gypsum board and 24 in. (610 mm) on
centers into the stud or furring channel in the field of the
13.3 Delay the joint treatment until the gypsum board is
gypsum board.
firmly bonded.
15.3.3 Screw spacing for a perpendicularly applied base-ply
13.4 Foil-backed gypsum board shall not be used for direct
of two-ply gypsum board over steel framing with no adhesive
adhesive application.
between the plies shall be not less than one screw at each edge
of the gypsum board at each framing member and one screw
13.5 Direct adhesive application shall be used only on
interior masonry or concrete walls above grade, or the inside of midway between the edges at each framing member.
15.3.4 Screw spacing for perpendicular or parallel applied
exterior masonry cavity walls with 1 in. (25 mm) minimum
width cavity between the inside and outside masonry for the base-ply of two-ply gypsum board over steel framing with
adhesive between plies shall be not more than as specified for
full height of the above grade surface to receive gypsum board.
Surfaces to which gypsum board is to be adhesively attached single-ply gypsum board in 8.5.
15.3.5 Screw spacing on ceilings for the face-ply of two-ply
shall be free of any foreign matter, projections, or depressions
that will impair the bond. gypsum board over steel framing with adhesive between plies
shall be the same as specified for the base-ply gypsum board in
14. System VII—Application of Gypsum Board to Rigid 15.3.2 and 15.3.3.
15.3.6 On wall surfaces with adhesive between the plies, the
Plastic Foam Insulation
face-ply shall have only a sufficient number of screws to hold
14.1 Application of Furring and Plastic Foam Insulation to
gypsum board in place.
Masonry and Concrete Walls:
14.1.1 Rigid foam insulation shall be applied to the masonry
16. System IX—Arches and Bending Radii
or concrete in accordance with the foam manufacturer’s
16.1 Where gypsum board is to be applied to the soffit of
specifications.
arches, it shall be carefully bent into place (see Table 7). If
14.1.2 Furring strips or special metal furring members shall
necessary, it first shall either be dampened or cut approxi-
be attached by mechanical means to the masonry or concrete
mately 1 in. (25 mm) on centers on the back side. In the latter
wall surface either before or after application of the insulation,
case, after the core has been broken at each cut, the gypsum
depending on the system used. The furring members shall be
board shall be applied to the curved framing member and
installed in accordance with Table 2 and at gypsum board
fastened in place. At the arises of the arch (exterior or interior
terminations above suspended ceilings, around doors,
“corners” formed at the meeting of the adjoining angle
windows, or other openings, and for cabinet and fixture
surfaces), joint compound and joint tape or corner bead shall be
attachment.
applied. The tape or corner bead shall be snipped at intervals
14.2 The gypsum board shall be applied to furring as
along one side so that the applied tape or corner bead conforms
described in 8.4.1 or 8.5. The mechanical fasteners shall not
to the curved contour.
penetrate completely to the masonry or concrete.
NOTE 8—To apply the board, place a stop at one end of the curve, then
gently and gradually push on the other end of the board, forcing the center
15. System VIII—Application of Gypsum Board to Steel
against the framing until the curve is complete.
Framing and Furring
NOTE 9—By thoroughly moistening the face and back paper and
allowing the water to soak well into the core, the board will bend to still
15.1 Screw application shall be applied in accordance with
7.1.6.
15.1.1 Screws shall be of sufficient length so that the
TABLE 7 Bending Radii
threaded portion shall penetrate not less than ⁄8 in. (9 mm) into
Gypsum Board Bent Lengthwise, ft
Bent Widthwise, ft (m)
the framing members.
Thickness, in. (mm) (m)
15.1.2 Where resilient furring channels are used, the screws
1 A
⁄2 (12.7) 10 (3.05) —
3 1
used to attach gypsum board to the furring channels shall not ⁄8 (9.5) 7 ⁄2 (2.29) 25 (7.62)
⁄4 (6.4) 5 (1.52) 15 (4.57)
contact the framing.
A
1 1
Bending two ⁄4 in. (6.4 mm) panels successively permits radii shown for ⁄4 in.
15.2 Framing Spacing—Maximum spacing of steel framing
(6.4 mm).
and furring for screw application shall be as specified in Table
C840 − 23
shorter radii. When the board thoroughly dries, it will regain its original
17.3.3 For installation of ceramic tile to gypsum boards see
hardness. Any subsequent joint treatment or decoration shall not be started
ANSI A108.
until the gypsum board is thoroughly dry.
18. System XI—Application of Exterior Gypsum Soffit
17. System X—Application of Gypsum Board to Receive
Board or Other Gypsum Board for Use in Exterior
Til
...

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: C840 − 20 C840 − 23
Standard Specification for
Application and Finishing of Gypsum Board
This standard is issued under the fixed designation C840; 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 U.S. Department of Defense.
1. Scope*
1.1 This specification covers the minimum requirements for the methods of application and finishing of gypsum board, including
related items and accessories.accessories to interior walls and ceilings and to exterior soffits.
1.2 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.
1.2.1 Where this specification is more stringent (size or thickness of framing: size and spacing of fasteners) than the fire-rated
construction, this specification shall govern.
1.3 Where sound control is required for a gypsum board assembly, details of construction shall be in accordance with reports of
acoustical tests of assemblies that have met the required acoustical values.
1.4 Unheated spaces above gypsum board ceilings shall be properly ventilated (see Appendix X2).
1.5 The various application systems are located in the following sections:
I Application of Single-ply Gypsum Board to Wood Framing Members 8
II Application of Two-ply Gypsum Board to Wood Framing Members 9
III Application of Gypsum Board by Adhesive Nail-on to Wood Framing 10
Members
IV Semi-solid Gypsum Board Partitions 11
V Solid Gypsum Board Partitions 12
VI Application of Gypsum Board with Adhesives to Interior Masonry or 13
Concrete Walls
VII Application of Gypsum Board to Rigid Foam Insulation 14
VIII Application of Gypsum Board to Steel Framing and Furring 15
IX Arches and Bending Radii 16
X Application of Gypsum Board to Receive Tile by Adhesive Application 17
XI Exterior Application of Gypsum Wallboard and Exterior Gypsum Soffit 18
Board
XI Application of Exterior Gypsum Soffit 18
Board or Other Gypsum Board for Use in Exterior Soffits
XII Floating Interior Angles 19
XIII Control (Expansion) Joints 20
XIV Foil-backed Gypsum Board 21
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 May 1, 2020Oct. 1, 2023. Published June 2020December 2023. Originally approved in 1979. Last previous edition approved in 20192020 as
C840 – 19b.C840 – 20. DOI: 10.1520/C0840-20.10.1520/C0840-23.
*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
C840 − 23
XV Application of Vinyl Faced Gypsum Board 22
1.6 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.
1.7 The text of this specification references notes and footnotes which provide explanatory material. These notes and footnotes
(excluding those in tables and figures) shall not be considered as requirements of the specification.
1.8 The following precautionary caveat pertains only to Sections 6 – 26. This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety,
health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific
precautionary statements, see 4.1.1, 4.1.2, and 24.5.
1.9 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
2.1 ASTM Standards:
C11 Terminology Relating to Gypsum and Related Building Materials and Systems
C475/C475M Specification for Joint Compound and Joint Tape for Finishing Gypsum Board
C514 Specification for Nails for the Application of Gypsum Board
C557 Specification for Adhesives for Fastening Gypsum Wallboard to Wood Framing
C645 Specification for Nonstructural Steel Framing Members
C754 Specification for Installation of Steel Framing Members to Receive Screw-Attached Gypsum Panel Products
C920 Specification for Elastomeric Joint Sealants
C954 Specification for Steel Drill Screws for the Application 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
C955 Specification for Cold-Formed Steel Structural Framing Members
C1002 Specification for Steel Self-Piercing Tapping Screws for Application of Gypsum Panel Products or Metal Plaster Bases
to Wood Studs or Steel Studs
C1007 Specification for Installation of Load Bearing (Transverse and Axial) Steel Studs and Related Accessories
C1047 Specification for Accessories for Gypsum Wallboard and Gypsum Veneer Base
C1396/C1396M Specification for Gypsum Board
C1546 Guide for Installation of Gypsum Products in Concealed Radiant Ceiling Heating Systems
E2634 Specification for Flat Wall Insulating Concrete Form (ICF) Systems
2.2 U.S. Department of Commerce Publication:
PS20 American Softwood Lumber Standard
2.3 ANSI Standards:
ANSI A108 Specifications for the Installation of Ceramic Tile
ANSI A136.1 Specifications for Organic Adhesives for Installation of Ceramic Tile, Type I and Type II
2.4 AISI Standards:
S220 North American Standard for Cold-Formed Steel Framing – Nonstructural Members
S240 North American Standard for Cold-Formed Steel Structural Framing
3. Terminology
3.1 Definitions—Definitions shall be in accordance with Terminology C11.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 critical lighting, n—a condition where interior surfaces are flooded by natural or artificial lighting at an oblique angle.
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.
Available from U.S. Government Printing Office, Superintendent of Documents, 732 N. Capitol St., NW, Washington, DC 20401-0001, http://www.access.gpo.gov.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Available from American Iron and Steel Institute (AISI), 25 Massachusetts Ave., NW, Suite 800, Washington, DC 20001, http://www.steel.org.
C840 − 23
3.2.2 decoration, n—paint (including primers), texture, coatings, and coverings such as wallpaper and sheet plastic a material or
materials designed to conceal or protect the surface of the gypsum board (see Appendix X3).
3.2.3 dry type, n—a compound in powder form to be mixed with water before use.
3.2.4 drying type, n—a joint compound that hardens by the evaporation of the vehicle used to make the paste. due to evaporation.
3.2.5 drywall primer, n—a paint material specifically formulated to fill the pores and minimize the suction difference between
gypsum board surface paper and the compound used on finished joints, angles, fastener heads and accessories, and over skim
coatings.
3.2.5 face panel, n—outside ply of multiple layer gypsum board assemblies.
3.2.6 finished wallboard, finish(ing), n—v—wallboard that has had the joints taped, has had the joints, fastener heads, and the act
of concealing joints with joint compound and tape; concealing fastener heads and edges or flanges of accessories concealed with
joint compound, and has been sanded to prepare the surface to receive job applied decoration. with joint compound.
3.2.8 finishing, n—the preparation of gypsum board surfaces to receive the field application of decoration.
3.2.9 finishing of accessories, n—the application of compound to flanges of accessories to create a monolithic surface.
3.2.7 flange, n—that part of an accessory extending over the face of the gypsum wallboardboard intended to become a part of the
monolithic plane of the prepared surface.
3.2.11 harden, v—a condition reached when the compound has lost its plasticity to an arbitrary degree, measured in resistance to
penetration or deformation.
3.2.8 joint photographing, n—a condition where the finished joint areas are visible after final decoration.
3.2.9 joint treatment, n—application of joint tape and compound to the joint between gypsum boards.
3.2.10 laminating compound, n—a compound (abrasive) material used to adhere gypsum board to gypsum board or other
monolithic materials.
3.2.11 moderate contact, n—the edges and ends are butted at joints but not forced together.
3.2.11.1 Discussion—
Small gaps not greater than ⁄4 in. (6 mm) are acceptable (see 7.4).
3.2.12 parallel or vertical application, n—gypsum board applied with the edges parallel to the framing member to which it is
attached.
3.2.13 perpendicular or horizontal application, n—gypsum board application with the edges applied at right angles to the framing
member to which it is attached.
3.2.14 ready-mix type, n—a factory-prepared compound ready to be used without the addition of water.
3.2.19 required, adj—pertaining to a mandatory obligation imposed by a force outside this specification, such as a building code,
project specification, contract, or purchase order.
3.2.15 setting type, n—a joint compound that hardens by a chemical reaction and increases in strength through drying.
3.2.16 skim coat, n—a thin layer of skim coat compound applied either a thin coat joint compound applied at a trowel consistency
C840 − 23
or a material manufactured specifically for this purpose, applied in accordance with manufacturer’s recommendations over the
entire surface of finished gypsum board.surface.
3.2.16.1 Discussion—
A skim coat is essentially a film of joint compound and is not applied at a readily measurable thickness. There is no specific mil
thickness that constitutes a proper skim coat (see Appendix X7).
3.2.22 skim coat compound, n—joint compound, or a material specifically formulated and manufactured for use as a skim coat.
3.2.17 specified,spotted, adj—pertaining to a mandatory requirement of this specification or a referenced requirement (see a
fastener head that has been covered with joint compound.3.2.17).
3.2.24 spotting fastener heads, n—the application of compound to cover the fastener head to create a monolithic surface.
3.2.25 taping of joints, n—the application of compound and joint reinforcing tape to the joints between adjoining gypsum boards.
3.2.18 treated joint, n—a joint between gypsum boards that has been covered with joint is reinforced with tape and joint compound
as specified in 24.3.3.1, 24.3.3.2, or 24.3.3.3. covered by strip moldings.
3.2.26.1 Discussion—Strip moldings or similar devices shall be permitted.
4. Environmental Conditions
4.1 Application of Gypsum Board, Joint Treatment Materials, and Adhesives—Room temperature shall be maintained at not less
than 40 °F (4 °C)40 °F (4 °C) during application of gypsum board except when adhesive is used for the attachment of gypsum
board. For the bonding of adhesive, joint treatment, texturing, and decoration, the room temperature shall be maintained at not less
than 50 °F (10 °C) for 48 h50 °F (10 °C) for 48 h prior to application and continuously thereafter until completely dry. occupancy.
See X7.7 for additional detail regarding environmental control during the installation and finishing process.
4.1.1 When a temporary heat source is used, the temperature shall not exceed 95 °F (35 °C)95 °F (35 °C) in any given room or
area.
4.1.2 Adequate ventilation shall be maintained in the working area during installation and curing period.
4.1.2.1 When portable gas or kerosene heaters are used, the extra humidity that they produce shall be removed by ventilation or
mechanical dehumidification.
4.2 Gypsum board shall be protected from direct exposure to rain, snow, sunlight, or other excessive weather conditions.
NOTE 1—Where manufacturers’ recommendations differ from the above, follow their recommendations.
4.3 Ready-mixed joint compounds shall be protected from freezing, exposure to extreme heat, and direct sunlight.
5. Materials and Manufacture
5.1 Gypsum Boards—A family of gypsum sheet products as defined in Terminology C11.
5.1.1 Type X (Special Fire-resistant) Gypsum Wallboard, Gypsum Backing Board, Water-resistant Gypsum Backing Board, or
Exterior Gypsum Soffıt Board—Gypsum board that provides a greater degree of fire resistance than regular gypsum board as
defined in Specification C1396/C1396M.
5.1.2 Foil-backed Gypsum Wallboard or Gypsum Backing Board—Regular or Type X gypsum board with foil laminated to the
back surface. The foil is a vapor retarder.
5.1.3 Predecorated Gypsum Board—Gypsum board with a decorative wall covering wallcovering or coating applied in-plant by
the gypsum board manufacturer.
5.2 Gypsum Wallboard—See Specification C1396/C1396M.
C840 − 23
5.3 Gypsum Backing Board and Coreboard—See Specification C1396/C1396M.
5.4 Water-resistant Gypsum Backing Board—See Specification C1396/C1396M.
5.5 Exterior Gypsum Soffıt Board—See Specification C1396/C1396M.
5.6 Gypsum Ceiling Board—See Specification C1396/C1396M.
5.7 Finishing Materials:
5.7.1 Compounds—Taping compound, finishing compound, and all-purpose compound shall meet the requirements of Specifi-
cation C475/C475M.
5.7.2 Mix compounds in accordance with the manufacturers’ directions.
5.7.3 Joint Tape—See Specification C475/C475M.
5.8 Fasteners:
5.8.1 Nails—See Specification C514.
5.8.1.1 Nails for use with pressure treated lumber shall be compatible with the preservative treated and fire retardant treated
lumber.
5.8.2 Screws:
5.8.2.1 See Specification C1002 for screws for fastening gypsum board to wood members, steel members less than 0.033 in.
(0.84 mm) in thickness, and to gypsum board.
5.8.2.2 See Specifications C754 and C954 for screws for fastening gypsum board to steel members from 0.0330.033 in. to
0.112 in. (0.84 to(0.84 mm to 2.84 mm) in thickness.
5.8.2.3 Screws for use with pressure treated lumber shall be compatible with the preservative treated and fire retardant treated
lumber.
5.8.3 Staples—No. 16 USS gauge flattened galvanized wire staples with ⁄16 in. (11 mm) wide crown outside measurement. Legs
shall have divergent points.
NOTE 2—Use only for the base ply of two-ply gypsum board application.
5.8.3.1 Staples for use with pressure treated lumber shall be compatible with the preservative treated and fire retardant treated
lumber.
5.9 Adhesives:
5.9.1 Fastening Gypsum Board to Wood Framing—See Specification C557.
5.9.2 Fastening Gypsum Board to Steel Framing—As specified by the manufacturer.
5.9.3 Laminating Gypsum Board to Gypsum Board—Laminating compounds, taping compound, or adhesive shall be as specified
by the manufacturer.
5.10 Framing Members:
C840 − 23
5.10.1 Wood framing members shall conform to PS20, American Softwood Lumber Standards. The surface to which abutting
edges or ends are attached shall be not less than 1 ⁄2 in. (38 mm) wide. For internal corners or angles, the bearing surface shall
not be less than ⁄4 in. (19 mm).
5.10.2 Steel Studs, Furring Channels, and Runners:
5.10.2.1 Non-load-bearing (see Specification C645 or AISI S220).
5.10.2.2 Load-bearing (see Specification C955 or AISI S240).
5.10.3 Gypsum Studs—Specification C1396/C1396M, not less than 1 in. (25 mm) thick by 6 in. (150 mm) wide. Studs shall be
either solid or laminated.
5.11 Accessories—See Specification C1047.
5.12 Water—Water shall be clean, fresh, and potable (suitable for domestic consumption).
1 5
5.13 Face Panels—Face panels shall be ⁄2 in. (12.7 mm), ⁄8 in. (15.9 mm), or multiple laminations of regular or Type X gypsum
board.
5.14 Core Board—Core board shall be ⁄4 or 1 in. (19 in. or 1 in. (19 mm or 25.4 mm) either single thickness or multiple layers
to the required 25 mm 25 mm thickness.
6. Substrate, Surface Preparation
6.1 The attachment surface of any framing member shall not vary more than ⁄8 in. (3 mm) from the plane of the faces of adjacent
framing members.
6.2 Wood framing shall be as straight and true as possible. Wood framing shall be securely attached following acceptable
engineering practices and as required for the intended design.
NOTE 3—For installation of wood framing, see Appendix X4.
6.3 Metal framing members shall be of the proper size and design for their intended use and shall be installed in accordance with
Specifications C754 or C1007 as required.
6.4 Where used as an alternative to framing, backing, or blocking, specially designed corner clips and edge clips shall be applied
in accordance with their listings or approvals and the clip manufacturer’s recommendations.
6.5 Devices or items attached to framing members, including the fasteners used to attach such devices or items, shall not protrude
more than ⁄8 in. (3 mm) beyond the surface to which the gypsum board is to be applied.
6.6 Masonry or concrete walls shall be dry, free of dust, oil, or form release agents, protrusions or voids, or foreign matter that
inhibit bond for adhesively applied gypsum board.
6.7 All framing members and substrate shall be installed so that after the gypsum board has been applied, the finished surface will
be in an even plane.
6.8 Gypsum board shall be kept free of any dirt, oil, or other foreign matter that cause a lack of bond. Foreign matter shall be
removed.
6.9 All dents or gouges on the face of the gypsum board shall be brought up to a smooth level plane with the surface of the board.
C840 − 23
6.10 Mechanical fasteners shall be set below the plane of the surface of the board.
6.11 All joints shall be true and even.
6.12 All gypsum board shall be tight against the framing member or substrate.
6.13 Deflection at design load of horizontal (ceiling) framing members supporting gypsum board shall be not more than L/240
of the span.
7. Application of Gypsum Board
7.1 General:
7.1.1 Method of Cutting and Installation—Gypsum board shall be cut by scoring and breaking or by sawing, working from the
face side. When cutting by scoring, the face paper shall be cut with a sharp knife or other suitable tool. Gypsum board shall be
broken by snapping the gypsum board in the reverse direction, or cut the back paper with a knife or suitable tool.
7.1.1.1 When cutting gypsum panels composed of two or more layers of gypsum board laminated together, both sides shall be
scored deeply and then broken by snapping the gypsum board in either direction or by cutting with a hand or power tool.
7.1.1.2 When cutting gypsum panels having an attached laminate, the laminate side shall be scored or cut with a knife, or the panel
shall be cut with a hand or power tool.
7.1.2 Cut edges and ends of the gypsum board shall be smoothed to obtain neat joints when installed. Holes for pipes, fixtures,
or other small openings shall be scored on the back and the face in outline before removal or cut out with a saw or special tool
designed for this purpose. Where gypsum board meets projecting surfaces, it shall be scribed and cut neatly.
7.1.3 When gypsum board is to be applied to both ceiling and walls, the gypsum board shall be applied first to the ceiling and
then to the walls.
7.1.3.1 Gypsum board applied to walls shall be applied with the bottom edge spaced not less than ⁄4 in. (6 mm) above the floor.
7.1.4 Where used at edges or ends, fasteners shall be spaced not more than 1 in. (25 mm) from edges and not less than ⁄8 in. (10
mm) from edges and ends of gypsum board (except where floating angles are used). Perimeter fastening into the partition plate
or sole at the top and bottom shall not be required except where the fire ratings, structural performance, or other special conditions
require such fastening. While driving the fasteners, the gypsum board shall be held in firm contact with the underlying support.
Application of fasteners shall proceed from the center or field of the gypsum board to the ends and edges.
7.1.5 Nails shall be driven with the heads slightly below the surface of the gypsum board, avoiding damage to the face and core
of the board, such as breaking the paper or fracturing the core.
7.1.5.1 Length of nails shall be as shown in Table 1.
7.1.6 Screws shall be driven to provide screw head penetration just below the gypsum board surface without breaking the surface
paper of the gypsum board and without spinout.
NOTE 4—Refer to Appendix X8 for guidance on some of the potential ways to minimize screw spinout in framing.
7.1.6.1 Length of screws shall be as shown in Table 1.
7.1.7 Staples shall be driven with the crown parallel to the framing members, in such a manner that the crown bears tightly against
the gypsum board without cutting into the face paper.
7.1.7.1 Staple attachment shall be restricted to the base plies only of gypsum board in a multi-ply system.
7.1.7.2 Length of staples shall be as shown in Table 1.
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TABLE 1 Fastener Length for Gypsum Board Application to
A
Wood Framing
Minimum Minimum
Gypsum Board Minimum Nail
D
Screw Staple
B C
Thickness Length
Length
Length
in. (mm) in. (mm)
in. (mm)
in. (mm)
E E E
⁄4 (6.4)
3 1
⁄8 (9.5) 1 ⁄4 (32) 1 (25) 1 (25)
1 3 1 1
⁄2 (12.7) 1 ⁄8 (35) 1 ⁄8 (28) 1 ⁄8 (28)
5 1 1 1
⁄8 (15.9) 1 ⁄2 (38) 1 ⁄4 (32) 1 ⁄4 (32)
A
Where fire resistance is required for gypsum board systems, fasteners of the
same or larger length, shank diameter, and head bearing area as those described
in the fire-rated design shall be used.
B
For other thicknesses, for multi-layer applications, or for application over rigid
foam insulation, fasteners shall be of sufficient length to penetrate framing not less
7 5 5
than ⁄8 in. (22 mm) for nails, ⁄8 in. (16 mm) for screws, and ⁄8 in. (15 mm) for
staples.
C
The maximum penetration for nails shall not exceed 1 ⁄4 in. (32 mm).
D
Staple attachment is restricted to base layers of multi-layer systems only. See
7.1.7.1.
E
For application over existing solid surfaces or in multi-layer applications only. See
footnote B above for required fastener length.
7.1.8 The gypsum board shall be kept tight against the framing.
7.1.9 The external corners shall be protected with a metal corner bead or other suitable type of corner protection (see Specification
C1047) that shall be attached to supporting construction with fasteners or a crimping tool nominally 6 in. (150 mm) on centers
(see Section 3 and Fig. 1), or with an adhesive manufactured especially for this purpose. For paper faced corner bead with paper
wings for attachment, attach with all-purpose or taping joint compound meeting the requirements of Specification C475/C475M.
NOTE 1—All dimensions are in inch-pound units.
FIG. 1 Accessories
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7.2 Gypsum board shall not be used where it will be exposed to temperatures more than 125 °F (52 °C) for extended periods of
time.
7.3 Gypsum board joints shall be located so that no joint will align with the edge of an opening unless control joints are to be
installed at these locations.
7.4 Joints between gypsum boards shall be constructed with the gypsum board edges in moderate contact.
7.5 Joints shall be staggered, and joints on opposite sides of a partition shall not occur on the same stud.
7.6 Gypsum board used in building construction shall be not less than 8 in. (200 mm) from the finished grade in fully weather
and water protected siding systems, and not less than 12 in. (300 mm) from the ground within properly drained and ventilated crawl
spaces. Where ground moisture or humidity is extreme or continuous, or both, the crawl space ground surface shall be covered
with a vapor barrier.
8. System I—Application of Single-ply Gypsum Board to Wood Framing Members
8.1 The maximum spacing for framing members for single-ply gypsum board assembly shall not exceed those shown in Table 2.
8.1.1 The ⁄4 in. (6.4 mm) thick gypsum board shall not be used in single-ply applications on either walls or ceilings.
8.2 In single-ply installation, all ends and edges of gypsum board shall occur over framing members or other solid backing except
where treated joints occur at right angles to framing or furring members.
8.3 End joints shall be staggered and joints on opposite sides of a partition shall be arranged to occur on alternate framing
members.
8.4 Application using nails.
8.4.1 Where a specific degree of fire resistance is required for gypsum board assemblies, nails of the same length, shank diameter,
and head bearing area, as those described in the fire test report, shall be used.
A
TABLE 2 Maximum Framing Spacing for Single-ply Construction
Maximum
Single-ply Framing
Gypsum Board Members On
B
Application
Thickness, in. Centers
(mm) Spacing, in.
(mm)
Ceilings:
C
⁄8 (9.5) perpendicular 16 (406)
⁄2 (12.7) parallel 16 (406)
⁄8 (15.9) parallel 16 (406)
⁄2 (12.7) perpendicular 24 (610)
⁄8 (15.9) perpendicular 24 (610)
Sidewalls:
⁄8 (9.5) perpendicular or parallel 16 (406)
⁄2 (12.7) perpendicular 24 (610)
or or
⁄8 (15.9) parallel
A
Gypsum board ceilings to receive hand or spray-applied water-based texture
material shall be applied perpendicular to framing and shall be either (i) ⁄2 in.
(12.7 mm) Gypsum Ceiling Board (see Specification C1396/C1396M) applied to
framing not more than 24 in. (610 mm) on center, or (ii) other gypsum boards not
less than ⁄2 in. (12.7 mm) thick for 16 in. (406 mm) on center framing and not less
than ⁄8 in. (15.9 mm) thick for 24 in. (610 mm) on center framing.
B
Nails for gypsum board applied over existing surfaces shall have a flat head and
diamond point, and shall penetrate not less than ⁄8 in. (22 mm), nor more than
1 ⁄4 in. (32 mm) into the framing member.
C 3
⁄8-in. in. (9.5 mm) single-ply gypsum board shall not be applied to ceilings where
the gypsum board supports insulation.
C840 − 23
8.4.2 Single Nailing—Nails shall be spaced a maximum of 7 in. (175 mm) on centers on ceilings, and a maximum of 8 in.
(200 mm) on centers on walls (see Fig. 2).
8.4.3 Double Nailing—Nails shall be spaced as shown in Fig. 3 and driven as follows:
8.4.3.1 Starting at the center of the gypsum board, nails shall be applied as shown in solid dots in row 1, then rows 2 and 2A,
3 and 3A, 4 and 4A, always nailing from center to edges of sheet. The gypsum board shall be kept tight against the framing.
8.4.3.2 Second nails, shown by circles, shall be applied in the same manner as the first nails, also starting at row 1.
8.4.3.3 As an alternative procedure, the second nail shall be applied immediately after all nails in each row are driven in
accordance with 8.4.3.2.
FIG. 2 Single Nailing
C840 − 23
FIG. 3 Double Nailing
8.4.3.4 Single nailing shall be used on the perimeter of the gypsum board, unless otherwise specified.
8.4.3.5 Nails shall be inspected for compliance with 7.1.5 after the second nails have been set.
8.5 Spacing of Screws—Screws shall be spaced not more than 12 in. (300 mm) on centers along framing members for ceilings and
16 in. (406 mm) on centers for walls where the framing members are 16 in. (406 mm) on centers. Screws shall be spaced not more
than 12 in. (300 mm) on centers along framing members for ceilings and walls where the framing members are 24 in. (610 mm)
on centers.
8.5.1 When using a combination of fasteners consisting of nails along the perimeter and screws in the field of the gypsum board,
the spacing between a nail and an adjacent screw shall be not more than the spacing specified for screws in 8.5.
9. System II—Application of Two-ply Gypsum Board to Wood Framing Members
9.1 The maximum spacings for framing members for two-ply gypsum board assemblies shall not exceed those shown in Tables
3 and 4.
NOTE 5—See Section 2 for adhesive application method.
9.2 The fastener length for the base ply of gypsum board shall be as indicated in Table 1.
9.2.1 Base layer end joints parallel to and on the same side of framing members shall be staggered between alternate courses of
gypsum board and from base layer joints on the opposite side of the framing members.
9.2.2 Base layer edge joints parallel to framing members shall be staggered on opposite sides of the framing members.
A
TABLE 3 Maximum Framing Spacing for Two-ply Assemblies, Fasteners Only, No Adhesive Between Plies
Gypsum Board Thickness,
Maximum On Centers
Application Direction
in. (mm)
Spacing of Framing,
in. (mm)
Base Ply Face Ply Base Ply Face Ply
Ceilings:
1 3 1
⁄4 (6.4) ⁄8 (9.5) or ⁄2 (12.7) perpendicular perpendicular 16 (406)
3 3 1
⁄8 (9.5) ⁄8 (9.5) or ⁄2 (12.7) perpendicular perpendicular 16 (406)
1 3 1
⁄2 (12.7) ⁄8 (9.5) or ⁄2 (12.7) parallel perpendicular 16 (406)
1 1 5
⁄2 (12.7) ⁄2 (12.7) or ⁄8 (15.9) perpendicular perpendicular 24 (610)
B
5 1 5
⁄8 (15.9) ⁄2 (12.7) or ⁄8 (15.9) perpendicular perpendicular 24 (610)
Walls:
1 1 3 1
⁄4 (6.4) ⁄4 (6.4) or ⁄8 (9.5) or ⁄2 (12.7) perpendicular or parallel perpendicular or parallel 16 (406)
3 1 3
⁄8 (9.5) ⁄4 (6.4) or ⁄8 (9.5) perpendicular or parallel perpendicular or parallel 16 (406)
1 1 3 1
⁄2 (12.7) ⁄4 (6.4) or ⁄8 (9.5) or ⁄2 (12.7) perpendicular or parallel perpendicular or parallel 24 (610)
5 1 3 1 5
⁄8 (15.9) ⁄4 (6.4) or ⁄8 (9.5) or ⁄2 (12.7) or ⁄8 (15.9) perpendicular or parallel perpendicular or parallel 24 (610)
A 1
Gypsum board ceilings to receive hand or spray-applied water-based texture material shall be applied perpendicular to framing and shall be either (i) ⁄2 in. (12.7 mm)
Gypsum Ceiling Board (see Specification C1396/C1396M) applied to framing not more than 24 in. (610 mm) on center, or (ii) other gypsum boards not less than ⁄2 in.
(12.7 mm) thick for 16 in. (406 mm) on center framing and not less than ⁄8 in. (15.9 mm) thick for 24 in. (610 mm) on center framing.
B
⁄8 in. (15.9 mm) board shall be permitted to be applied perpendicularly at 16 in. (406 mm) spacing.
C840 − 23
A
TABLE 4 Maximum Framing Spacing for Two-ply Assembly Fasteners with Adhesive Between Plies
Gypsum Board Thickness,
Maximum On
Application Direction
in. (mm)
Centers Spacing of
Framing, in. (mm)
Base Ply Face Ply Base Ply Face Ply
Ceilings:
1 1 3 1
⁄4 (6.4) ⁄4 (6.4) or ⁄8 (9.5) or ⁄2 (12.7) perpendicular perpendicular 16 (406)
3 1 3 1
⁄8 (9.5) ⁄4 (6.4) or ⁄8 (9.5) or ⁄2 (12.7) perpendicular perpendicular 16 (406)
1 1 3 1
⁄2 (12.7) ⁄4 (6.4) or ⁄8 (9.5) or ⁄2 (12.7) parallel perpendicular 16 (406)
1 1 1 5
⁄2 (12.7) ⁄4 (6.4) or ⁄2 (12.7) or ⁄8 (15.9) perpendicular perpendicular 24 (610)
5 1 1 5
⁄8 (15.9) ⁄4 (6.4) or ⁄2 (12.7) or ⁄8 (15.9) perpendicular perpendicular 24 (610)
Walls:
1 1 3 1
⁄4 (6.4) ⁄4 (6.4) or ⁄8 (9.5) or ⁄2 (12.7) perpendicular or parallel perpendicular or parallel 16 (406)
3 1 3
⁄8 (9.5) ⁄4 (6.4) or ⁄8 (9.5) perpendicular or parallel perpendicular or parallel 16 (406)
1 1 3 1
⁄2 (12.7) ⁄4 (6.4) or ⁄8 (9.5) or ⁄2 (12.7) perpendicular or parallel perpendicular or parallel 24 (610)
5 1 1 5
⁄8 (15.9) ⁄4 (6.4) or ⁄2 (12.7) or ⁄8 (15.9) perpendicular or parallel perpendicular or parallel 24 (610)
A
Adhesive between plies shall be dried or cured prior to joint treatment application.
9.3 When adhesive is not used between the plies, the two plies of gypsum board shall be applied as indicated in Tables 3 and 5.
The face ply shall be applied with the number of nails or screws required for normal single-ply application. Fastener length for
face ply application shall be as indicated in footnote B of Table 1. Face ply joints that are parallel to framing shall fall over framing
members and be offset from the base ply joints when two plies of gypsum board are parallel.
9.4 When an adhesive is used between the plies (laminated face ply), the two plies shall be applied as indicated in Tables 4 and
5. If the two plies are applied in parallel direction, the joints in the face ply shall be offset from the joints in the base ply.
9.4.1 Joints in the face ply need not occur over the framing members. The adhesive used between the two plies of gypsum board
shall be uniformly applied over the back surface of the face ply of the gypsum board before it is erected or to the face surface of
the base ply. The face ply of gypsum board shall be placed in position and fastened with nails or screws to hold gypsum board
in place until the adhesive develops a bond.
9.4.2 Permanent fasteners shall be used around the perimeter 12 in. (300 mm) on centers and 16 in. (400 mm) on centers along
framing members for the face ply of gypsum board applied on ceilings.
9.4.3 In place of nails and screws, the face ply of gypsum board applied on walls shall be held in position by shoring with props
and headers, or other temporary support to ensure a pressure for bonding. Permanent fasteners shall be used on top and bottom
of wall not more than 16 in. (400 mm) on centers. Nails or screws used to hold the gypsum board face ply shall be left in place
and finished in the same manner as for single-ply gypsum board application (see Section 10).
9.5 Base layer joints and fasteners shall not be required to be taped or finished. Face layer joints and fasteners in multi-layer
systems shall not be required to be finished unless required for appearance or decoration or as required for fire resistance.
10. System III—Application of Gypsum Board by Adhesive Nail-on to Wood Framing Members
10.1 Except as herein modified, application shall be in conformance with Section 8.
TABLE 5 Base Layer Fastener Spacing for Multi-layer Gypsum Board Application
Base Layer Base Layer Base Layer
Nail Spacing Screw Spacing Staple Spacing
in. (mm) in. (mm) in. (mm)
Where Face Where Face Where Face
Framing Where Face Layer is Where Face Layer is Where Face Layer is
Spacing Layer is Mechanically Layer is Mechanically Layer is Mechanically
Location in. (mm) Laminated Attached Laminated Attached Laminated Attached
Walls 16 (406) 8 (200) 24 (600) 16 (400) 24 (600) 7 (175) 16 (400)
24 (610) 8 (200) 24 (600) 12 (300) 24 (600) 7 (175) 16 (400)
Ceilings 16 (406) 7 (175) 16 (400) 12 (300) 24 (600) 7 (175) 16 (400)
24 (610) 7 (175) 16 (400) 12 (300) 24 (600) 7 (175) 16 (400)
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10.2 Surfaces of gypsum board and framing to receive the adhesive shall be free of dust, dirt, grease, or any other foreign matter
that cause bond loss. Foreign matter shall be removed.
10.3 A bead of adhesive ⁄8 in. (10 mm) in diameter shall be applied to the face of all wood framing members, except plates, that
3 1
support the gypsum board. The adhesive shall be spread to an average width of ⁄4 in. (20 mm) and an average thickness of ⁄16
in. (2 mm). See Fig. 4 for application patterns.
10.3.1 Where a joining of two adjacent pieces of gypsum board occurs on a framing member, two parallel beads of adhesive shall
be applied, one near each edge of the framing member.
10.4 Adhesive shall be applied to no greater area than can be covered with gypsum board within the “open time.”
NOTE 6—“Open time” is the time period available for working with certain adhesives before they set in accordance with the adhesive manufacturer’s
specification.
10.5 Fastener Spacing:
10.5.1 If the properties of the adhesive ensure bridging between the gypsum board and the wood framing, nailing shall not be
required in the field of the board for walls. In such cases, perimeter nailing, 16 in. (400 mm) on centers, shall be required.
10.5.2 When the properties of the adhesive are such that there is no positive bridging between the gypsum board and the wood
framing, either temporary field nailing or temporary bracing shall be used to ensure contact between the gypsum board, the
adhesive, and the wood framing, until the adhesive develops a bond.
10.5.3 Unless specified otherwise by the adhesive manufacturer, fastener spacing shall be in accordance with Table 6.
11. System IV—Semi-solid Gypsum Board Partitions
11.1 Installation:
11.1.1 Runners or studs shall be installed where required to provide support at exterior walls, partition junctions, terminals,
external corners, door frames, and at other locations.
11.1.2 The gypsum board face panels and studs shall be positioned vertically.
11.1.3 The gypsum studs shall be laminated to face panels not more than 24 in. (610 mm) on centers and located at face panel
vertical joints and at vertical centerline of panel.
11.1.4 Gypsum studs shall be laminated to face panels prior to erection or as erection of partition proceeds. A starter face panel
shall be erected vertically at an intersecting wall. The starter panel shall be plumb and secured to the floor, the ceiling, and the
vertical runners.
11.1.5 The next face panel adjacent to the starter panel shall be erected by butting its edge and end firmly to the starter panel and
the ceiling. Erection of the face panels shall continue by laminating exposed faces of gypsum studs as work progresses.
FIG. 4 Adhesive Application Patterns
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TABLE 6 Fastener Spacing with Adhesive or Mastic Application and Supplemental Fastening
Framing Member Partitions Load Bearing, Partitions Nonload
Ceilings, in. (mm)
Spacing, in. (mm) in. (mm) Bearing, in. (mm)
On Centers Nail Screw Nail Screw Nail Screw
16 (406) 16 (400) 16 (400) 16 (400) 24 (600) 24 (600) 24 (600)
24 (610) 12 (300) 16 (400) 12 (300) 16 (400) 16 (400) 24 (600)
11.1.6 Openings in partitions for doors and electrical outlets shall be carefully and accurately marked and cut.
11.1.7 Laminating compounds or adhesives shall be of a consistency and volume that will cover approximately three-fourths of
the stud surface after lamination.
11.1.8 Type G screws shall be used to ensure a continuous bond between face panels and studs, and shall be spaced not more than
36 in. (900 mm) on centers.
11.1.9 Openings or changes in direction of partitions shall be reinforced with additional studs laminated in place at the following
locations:
11.1.9.1 External Corners—Between the face panels in the corner opposite vertical runners.
11.1.9.2 Abutting Walls—Between the face panels of a partition to reinforce junction of an abutting wall.
11.1.9.3 Door Openings—Locate a vertical stud within 3 in. (75 mm) of door frame for reinforcement, and place a stud
horizontally over the door header.
12. System V—Solid Gypsum Board Partitions
12.1 Non-load-bearing solid partition consisting of gypsum coreboard faced on each side with gypsum board panels.
12.2 Installation:
12.2.1 Floor and ceiling runners shall be installed according to the layout and shall be secured not more than 24 in. (610 mm) on
centers. Vertical runners shall be installed where specified in 11.1.1.
12.2.2 For partitions located parallel to and between ceiling members, steel or wood blocking not more than 24 in. (610 mm) on
centers shall be provided to fasten ceiling runners prior to erection of ceiling.
12.2.3 Face panels shall be attached to runners at not more than 24 in. (610 mm) on centers.
12.2.4 Coreboard shall be installed prior to the installation of the face panel. Coreboard shall be attached not more than 24 in.
(610 mm) on centers to the steel angles when steel angles are used as runners. When steel channels are used as runners to secure
coreboard, attachment shall not be required.
NOTE 7—Combinations of wood and steel channels or angles will vary the installation procedure.
12.2.5 The adhesive shall be applied to the back surface of the face panels or the face of the coreboard as described for two-ply
gypsum board construction (see Section 9).
12.2.6 The face panels shall be laminated to the core with sufficient pressure to ensure bonding. The joints of the face panels and
core shall be staggered. To ensure the bond between face panels and core, fasteners shall be permitted.
13. System VI—Application of Gypsum Board with Adhesive to Interior Masonry or Concrete Walls
13.1 When applying gypsum board to monolithic concrete, brick, or concrete block, the adhesive shall be applied directly to the
back of the gypsum board or on the wall in continuous beads not more than 12 in. (300 mm) on centers or daubs spaced not more
than 12 in. (300 mm) on centers each way.
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13.1.1 Beads shall be not less than ⁄8 in. (10 mm) in diameter to provide a continuous bond between the gypsum board and the
wall surface.
13.1.2 Daubs shall be 2 to 3 in. (50 to 75 mm) 2 in. to 3 in. (50 mm to 75 mm) in diameter.
13.2 The gypsum board shall be positioned ⁄8 in. (3 mm) from the floor and provide a tight fit at abutting edges or ends. The
gypsum board shall not be slid on the adhesive. Mechanical fasteners, or temporary bracing, shall be used to support gypsum board
until adhesive sets.
13.3 Delay the joint treatment until the gypsum board is firmly bonded.
13.4 Foil-backed gypsum board shall not be used for direct adhesive application.
13.5 Direct adhesive application shall be used only on interior masonry or concrete walls above grade, or the inside of exterior
masonry cavity walls with 1-in.1 in. (25 mm) minimum width cavity between the inside and outside masonry for the full height
of the above grade surface to receive gypsum board. Surfaces to which gypsum board is to be adhesively attached shall be free
of any foreign matter, projections, or depressions that will impair the bond.
14. System VII—Application of Gypsum Board to Rigid Plastic Foam Insulation
14.1 Application of Furring and Plastic Foam Insulation to Masonry and Concrete Walls:
14.1.1 Rigid foam insulation shall be applied to the masonry or concrete in accordance with the foam manufacturer’s
specifications.
14.1.2 Furring strips or special metal furring members shall be attached by mechanical means to the masonry or concrete wall
surface either before or after application of the insulation, depending on the system used. The furring members shall be installed
in accordance with Table 2 and at gypsum board terminations above suspended ceilings, around doors, windows, or other openings,
and for cabinet and fixture attachment.
14.2 The gypsum board shall be applied to furring as described in 8.4.1 or 8.5. The mechanical fasteners shall not penetrate
completely to the masonry or concrete.
15. System VIII—Application of Gypsum Board to Steel Framing and Furring
15.1 Screw application shall be applied in accordance with 7.1.6.
15.1.1 Screws shall be of sufficient length so that the threaded portion shall penetrate not less than ⁄8 in. (9 mm) into the framing
members.
15.1.2 Where resilient furring channels are used, the screws used to attach gypsum board to the furring channels shall not contact
the framing.
15.2 Framing Spacing—Maximum spacing of steel framing and furring for screw application shall be as specified in Table 2 for
single-ply gypsum board and as specified in Tables 3 and 4 for two-ply gypsum board.
15.2.1 Installation of steel framing shall be in accordance with Specifications C754 or C1007.
15.3 Screw Spacing:
15.3.1 Screw spacing for single-ply gypsum board and face ply of two-ply gypsum board with no adhesive shall be in accordance
with 8.5.
15.3.2 Screw spacing for parallel applied base-ply of two-ply gypsum board over steel framing with no adhesive between the plies
C840 − 23
shall be not more than 12 in. (300 mm) on centers along the edges of the gypsum board and 24 in. (610 mm) on centers into the
stud or furring channel in the field of the gypsum bo
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