ASTM C1325

Full Name

ASTM C1325 – Standard Specification for Fiber-Mat Reinforced Cementitious Backer Units


This specification covers non-asbestos fiber-mat reinforced cementitious backer units manufactured to be dimensionally stable and suitable as either an unfinished substrate 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).


acceptance; air cured; appearance; density; edge straightness; finish; flexural strength; glass mat cement sheet; inspection; interior wet area application; length and width tolerance; mechanical properties; minimum equilibrium strength; minimum wet strength; moisture content; moisture movement; nominal length; nominal thickness; nominal width; non-asbestos fiber-mat; packaging; physical properties; pressure cured; sampling; shipping; squareness tolerance; storage; supplementary requirements; supplementary tests; surface burning characteristics; thickness requirements; thickness tolerance; third party certification; tolerance; type tests; warm water resistance; workmanship