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 a permanent form in poured-in-place reinforced gypsum concrete roof decks. Developed by ASTM International, this standard provides clear criteria for material composition, physical properties, dimensions, and finish quality to ensure the reliability and safety of gypsum formboard in construction. The specification addresses both inch-pound and SI units, making it suitable for international application and compliance with global building practices.

Key Topics

• Materials and Composition: Gypsum formboard must feature a noncombustible core, primarily gypsum, meeting specific criteria for content and fiber reinforcement. Fibers can be mineral or organic, synthetic or natural, constituting no more than 15% by weight.
• Surface Treatment: The formboard’s face is specially treated to resist fungus, supporting its use in humid or moisture-prone environments.
• Physical Properties: Rigorous testing is required, including:
  • Flexural strength (face up and face down)
  • Humidified deflection
  • Core, end, and edge hardness
  • Resistance to fungal growth
• Dimensions and Tolerances: The standard defines strict tolerances for thickness, width, length, and end squareness, ensuring boards are consistent and suitable for construction use without requiring mechanical fastening.
• Finish and Appearance: Surfaces must be true and free of imperfections to be fit for use, whether finished or unfinished.

Applications

ASTM C318/C318M-13(2018) is widely used in the construction industry, specifically for:

• Installation of Reinforced Gypsum Concrete Roof Decks: Used as a permanent forming material, gypsum formboard serves as a mold for poured-in-place roof deck systems, providing structural support and fire resistance.
• Commercial and Institutional Buildings: Ensures roof decks are constructed to meet safety and durability standards in schools, office spaces, hospitals, and other large structures.
• Moisture-Prone and Fire-Sensitive Environments: With its noncombustible core and fungus-resistant surface, gypsum formboard is ideal for buildings requiring enhanced resistance to moisture and fire hazards.
• Prevention of Fungal Growth: The specification for treated surfaces supports hygiene and longevity, particularly in climates or applications where moisture control is critical.

Related Standards

To ensure comprehensive compliance and performance, ASTM C318/C318M-13(2018) references and aligns with several other key ASTM standards:

• ASTM C11: Terminology Relating to Gypsum and Related Building Materials and Systems.
• ASTM C22: Specification for Gypsum - Sets base material requirements.
• ASTM C473: Test Methods for Physical Testing of Gypsum Panel Products - Outlines procedures for evaluating properties such as strength and hardness.
• 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.

These interconnected standards provide a robust framework supporting the quality, performance, and reliability of gypsum formboard across a variety of building applications.

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Keywords: gypsum formboard, ASTM C318, gypsum concrete, roof deck, construction standards, noncombustible, fungus resistance, material testing, building materials compliance, ASTM International

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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