ASTM C1325-21 - 1.7.2021
 
1. Scope

1.1?This specification covers non-asbestos fiber-mat reinforced cementitious backer units manufactured to be dimensionally stable and suitable as either an unfinished substrate (see Note 1) or as a substrate for decoration such as natural stone or tile on walls, floors, or decks in wet and dry areas. It is also suitable to be used as a substrate in the Application of Class PB Exterior Insulation Finish Systems (Practice C1397), the Application of Direct-Applied Finish Systems (Practice C1516), and the Application of Exterior Insulation Finish Systems Class PI (Practice C1535).

Note 1:?When used as an unfinished substrate, consult the manufacturer's written installation literature for proper application details.

1.2?This specification is not applicable to asbestos-cement flat sheets (Specification C220); non-asbestos fiber cement flat sheets for exterior applications such as claddings, facades, curtain walls, and soffits (Specification C1186); gypsum backing board, coreboard, and shaftliner (Specification C1396/C1396M); water-resistant gypsum backing board (Specification C1396/C1396M); glass mat gypsum backing board (Specification C1178/C1178M); particle boards (Definitions D1554); and discrete non-asbestos fiber cement interior substrate sheets (Specification C1288).

1.3?UnitsThe 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.

1.4?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.

 
2. Referenced Documents

C1154-24

Standard Terminology for Fiber-Reinforced Cement Products

C1535-05(2023)

Standard Practice for Application of Exterior Insulation and Finish Systems Class PI

D1037-12(2020)

Standard Test Methods for Evaluating Properties of Wood-Base Fiber and Particle Panel Materials

D1554-10(2023)

Standard Terminology Relating to Wood-Base Fiber and Particle Panel Materials

D2394-17(2022)

Standard Test Methods for Simulated Service Testing of Wood and Wood-Based Finish Flooring

E84-23d

Standard Test Method for Surface Burning Characteristics of Building Materials (Includes all amendments and changes 1/29/2024).

G21-15(2021)e1

Standard Practice for Determining Resistance of Synthetic Polymeric Materials to Fungi (Includes all amendments and changes 6/22/2021).

G22-23

Standard Practice for Determining Resistance of Plastics to Bacteria

A118.1

Specification for Dry-Set Portland Cement Mortar

C1516-05(2023)

Standard Practice for Application of Direct-Applied Exterior Finish Systems

A118.4

Specification for Latex-Portland Cement Mortar

A136.1

Standard for Organic Adhesives for Installation of Ceramic Tile

C473-19

Standard Test Methods for Physical Testing of Gypsum Panel Products

C220-91(1999)

Standard Specification for Flat Asbestos-Cement Sheets

C666-C666M-15

Standard Test Method for Resistance of Concrete to Rapid Freezing and Thawing (Withdrawn 2024)

C947-03(2023)

Standard Test Method for Flexural Properties of Thin-Section Glass-Fiber-Reinforced Concrete (Using Simple Beam With Third-Point Loading)

C1397-13(2019)

Standard Practice for Application of Class PB Exterior Insulation and Finish Systems (EIFS) and EIFS with Drainage

C1178/C1178M-18

Standard Specification for Coated Glass Mat Water-Resistant Gypsum Backing Panel

C1185-23

Standard Test Methods for Sampling and Testing Fiber-Cement Flat Sheet, Roofing and Siding Shingles, and Clapboards

C1186-22e1

Standard Specification for Flat Fiber-Cement Sheets (Includes all amendments and changes 10/10/2023).

C1288-23

Standard Specification for Fiber-Cement Interior Substrate Sheets

C1396/C1396M-17

Standard Specification for Gypsum Board