ASTM C318/C318M-13(2018)

Standard Specification for Gypsum Formboard

ABSTRACT
This specification covers the minimum requirements for gypsum formboard designed for use as a permanent form for poured-in-place reinforced gypsum concrete roof decks. Gypsum formboard shall consist of a noncombustible core, essentially gypsum, either mineral or organic, synthetic or natural. The face surface shall be specifically treated to resist fungus growth. Specimens shall be subjected to the following test methods: flexural strength; humidified deflection; core, end, and edge hardness; and resistance to fungi. Specimens shall be tested to determine thickness, width, length, end squareness, and edges and ends. The surfaces of gypsum formboard shall be true and free from imperfections that would render it unfit for use with or without decoration.
SCOPE
1.1 This specification covers the minimum requirements for gypsum formboard designed for use as a permanent form for poured-in-place reinforced gypsum concrete roof decks.  
1.2 The values stated in either inch-pound units or SI (metric) are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system shall be used independent of the other. Values from the two systems shall not be combined.  
1.3 The text of this standard references notes which provide explanatory material. These notes shall not be considered requirements of the standard.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Sep-2018
• ICS: 91.100.40 - Products in fibre-reinforced cement
• Technical Committee: C11 - Gypsum and Related Building Materials and Systems
• Drafting Committee: C11.01 - Specifications and Test Methods for Gypsum Products

Relations

• Replaces: ASTM C318/C318M-13 - Standard Specification for Gypsum Formboard
• Effective Date: 01-Oct-2018
• Refers: ASTM C473-19 - Standard Test Methods for Physical Testing of Gypsum Panel Products
• Effective Date: 01-Oct-2019
• Refers: ASTM C11-18a - Standard Terminology Relating to Gypsum and Related Building Materials and Systems
• Effective Date: 01-Oct-2018
• Refers: ASTM C11-18 - Standard Terminology Relating to Gypsum and Related Building Materials and Systems
• Effective Date: 01-Jun-2018
• Refers: ASTM C473-17 - Standard Test Methods for Physical Testing of Gypsum Panel Products
• Effective Date: 01-Oct-2017
• Refers: ASTM C11-17a - Standard Terminology Relating to Gypsum and Related Building Materials and Systems
• Effective Date: 01-Oct-2017
• Refers: ASTM C11-17 - Standard Terminology Relating to Gypsum and Related Building Materials and Systems
• Effective Date: 15-May-2017
• Refers: ASTM C473-16 - Standard Test Methods for Physical Testing of Gypsum Panel Products
• Effective Date: 01-Nov-2016
• Refers: ASTM C11-16 - Standard Terminology Relating to Gypsum and Related Building Materials and Systems
• Effective Date: 15-May-2016
• Refers: ASTM C11-15a - Standard Terminology Relating to Gypsum and Related Building Materials and Systems
• Effective Date: 01-Oct-2015
• Refers: ASTM C473-15 - Standard Test Methods for Physical Testing of Gypsum Panel Products
• Effective Date: 15-May-2015
• Refers: ASTM C11-15 - Standard Terminology Relating to Gypsum and Related Building Materials and Systems
• Effective Date: 01-Apr-2015
• Refers: ASTM C1264-14a - Standard Specification for Sampling, Inspection, Rejection, Certification, Packaging, Marking, Shipping, Handling, and Storage of Gypsum Panel Products
• Effective Date: 01-Sep-2014
• Refers: ASTM C1264-14 - Standard Specification for Sampling, Inspection, Rejection, Certification, Packaging, Marking, Shipping, Handling, and Storage of Gypsum Panel Products
• Effective Date: 15-Apr-2014
• Refers: ASTM G21-13 - Standard Practice for Determining Resistance of Synthetic Polymeric Materials to Fungi
• Effective Date: 01-Nov-2013

Overview

ASTM C318/C318M-13(2018) - Standard Specification for Gypsum Formboard establishes the minimum requirements for gypsum formboard used as permanent forms in poured-in-place reinforced gypsum concrete roof decks. Developed by ASTM International, this standard specifies material properties, performance criteria, dimensions, and tolerance levels, ensuring that formboard products meet industry-accepted quality and safety benchmarks. The document applies to both inch-pound and SI units, and was created in accordance with internationally recognized standardization principles.

Key Topics

• Material Composition:

  • Gypsum formboard must have a noncombustible gypsum core.
  • Core may include up to 15% fiber content, which can be mineral or organic, synthetic or natural.
  • The surface of the formboard is treated to resist fungal growth, enhancing durability in moist environments.

• Performance Requirements:

  • Critical tests include assessments for flexural strength, humidified deflection, core, end, and edge hardness, in addition to resistance to fungi.
  • Products must meet strict standards for thickness, width, length, squareness, and finish to ensure usability in roofing systems.

• Dimensional Tolerances:

  • Defined tolerances for thickness, width, length, and squareness to ensure compatibility with structural requirements.
  • Nominal thickness is generally 1/2 in. [12.7 mm], with precise permissible variations outlined in the standard.

• Finish and Appearance:

  • Gypsum formboards must have true, smooth surfaces, free from imperfections that could affect their fit or function, with or without surface decoration.

Applications

• Roof Deck Construction:

  • The primary function is as permanent formwork for poured-in-place reinforced gypsum concrete roof decks, commonly used in commercial, industrial, and institutional buildings.
  • Provides a stable base for concrete pouring, ensuring uniform deck thickness and supporting load-bearing requirements.

• Moisture-Resistant Systems:

  • Fungal-resistant face treatments make gypsum formboard suitable for use in roof structures where moisture exposure is a concern, helping maintain long-term durability and indoor air quality.

• Quality Assurance in Building Materials:

  • Reference to ASTM C318/C318M ensures that gypsum formboards supplied to a project will meet recognized benchmarks for structural performance and safety, supporting code compliance and risk management.

Related Standards

• ASTM C11: Terminology Relating to Gypsum and Related Building Materials and Systems.
• ASTM C22: Specification for Gypsum - the base material for the formboard core.
• ASTM C473: Test Methods for Physical Testing of Gypsum Panel Products - outlines procedures for testing the performance characteristics described in this standard.
• ASTM C1264: Specification for Sampling, Inspection, Rejection, Certification, Packaging, Marking, Shipping, Handling, and Storage of Gypsum Panel Products.
• ASTM G21: Practice for Determining Resistance of Synthetic Polymeric Materials to Fungi.

By referencing ASTM C318/C318M-13(2018), professionals in the construction and building materials industry can ensure the use of high-quality, fungus-resistant, and dimensionally accurate gypsum formboards, contributing to the safety, durability, and longevity of roof deck systems. This standard is vital for manufacturers, architects, structural engineers, contractors, and building inspectors focused on achieving project reliability and regulatory compliance.

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: C318/C318M −13 (Reapproved 2018)
Standard Specification for
Gypsum Formboard
This standard is issued under the fixed designation C318/C318M; 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* 3. Terminology
1.1 This specification covers the minimum requirements for
3.1 Definitions—Definitions of terms used in this standard
gypsum formboard designed for use as a permanent form for shall be in accordance with Terminology C11.
poured-in-place reinforced gypsum concrete roof decks.
4. Materials and Manufacture
1.2 The values stated in either inch-pound units or SI
(metric) are to be regarded separately as standard. Within the
4.1 Gypsum formboard shall consist of a noncombustible
text, the SI units are shown in brackets. The values stated in
core, essentially gypsum complying with Specification C22,
each system shall be used independent of the other. Values
containing not more than 15 % by weight of fiber, either
from the two systems shall not be combined.
mineral or organic, synthetic or natural.
1.3 The text of this standard references notes which provide
4.2 The face surface shall be specifically treated to resist
explanatory material. These notes shall not be considered
fungus growth.
requirements of the standard.
1.4 This international standard was developed in accor-
5. Physical Properties
dance with internationally recognized principles on standard-
5.1 Specimens shall be tested in accordance with Test
ization established in the Decision on Principles for the
Methods C473.
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
NOTE 1—Since this product is laid between subpurlins without me-
Barriers to Trade (TBT) Committee.
chanical attachment, a nail pull requirement is not specified for this
gypsum panel product.
2. Referenced Documents
5.1.1 Specimensshallbetakenfromthesamplesobtainedin
2.1 ASTM Standards:
accordance with Specification C1264.
C11 Terminology Relating to Gypsum and Related Building
5.1.2 Flexural Strength—The specimens shall be tested face
Materials and Systems
up and face down. The average breaking load shall be not less
C22 Specification for Gypsum
than the following:
C473 Test Methods for Physical Testing of Gypsum Panel
Bearing Edges Across Bearing Edges Par- Bearing Edges Par-
Products
Fiber of Surfacing, allel Fiber of Sur- allel Fiber of Sur-
C1264 Specification for Sampling, Inspection, Rejection,
lbf [N] facing, Face, lbf [N] facing, Back, lbf [N]
Method A 160 [715] 60 [270] 40 [180]
Certification, Packaging, Marking, Shipping, Handling,
Method B 157 [700] 56 [250] 36 [160]
and Storage of Gypsum Panel Products
G21 Practice for Determining Resistance of Synthetic Poly-
5.1.3 Humidified Deflection—The specimens shall have an
meric Materials to Fungi
average deflection of not more than the following:
Thickness, Humidified Deflection,
in. (mm) Eighths of an in. (mm)
⁄2 [12.7] 10 [32]
This specification is under the jurisdiction of ASTM Committee C11 on
Gypsum and Related Building Materials and Systems and is the direct responsibility
5.1.4 Core, End, and Edge Hardness—The specimens shall
of Subcommittee C11.01Specifications and Test Methods for Gypsum Products.
have an average hardness of 15 lbf [65 N] when tested by
Current edition approved Oct. 1, 2018. Published October 2018. Originally
Method A and 11 lbf [50 N] when tested by Method B.
approved in 195
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