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Input Sought to Identify Exterior Fiber-Reinforced Cement Products Suitable for Manufacture According to ASTM C 1325

Attendance is invited to a meeting of ASTM Committee C17 on Reinforced Cement Products, June 26-27, Norfolk, Va., to discuss a major revision to an ASTM standard for fiber-reinforced cement products. Input from manufacturers is needed to decide what exterior product specifications will be added to C 1325 Standard Specification for Non-Asbestos Fiber-Mat Reinforced Cement Interior Substrate Sheets.

The standard was originally published in 1996. “Revisions to C 1325 are needed in order to establish test methods and specifications for using the product as an exterior sheathing,” said Keith A. Poerschke, manager, Building Codes, Research Center, National Gypsum Co., Buffalo, N.Y. “The products currently manufactured to this standard are frequently used for this. They function quite well as an exterior sheathing, since it holds up very well when exposed to moisture.

“However, in order to write specifications for the product, several of the manufacturers are going to have to come to some agreements on what types of testing is needed. It may be that not all products currently manufactured to C 1325 can, or will, function adequately as an exterior sheathing. We expect concerns such as linear expansion, water absorption, freeze/ thaw resistance, etc. will need to be addressed to a greater degree than they are in the current standard.

As stated in the standard, C 1325 “covers fiber-mat reinforced cement substrate sheets manufactured to be dimensionally stable and suitable as either an unfinished substrate or as a substrate for decoration such as natural stone or tile in internal wet and dry areas.”

“The referenced tile and natural stone are ceramic tile, and stone cut into thin veneer to allow adhesive application to the cement board similar to a tile installation, using latex modified Portland cement mortars or other recommended adhesives,” Poerschke said. “As a manufacturer, it is our hope that the use of these products as an exterior sheathing will become more prevalent as a result of these changes to the standard.”

Architects, code officials, engineers, and contractors who reference C 1325 are highly encouraged to attend the meeting, or provide input to Keith A. Poerschke, manager, Building Codes, Research Center, National Gypsum Co., Buffalo, N.Y. (phone: 716/873-9750, ext. 234). Following the June meeting, C17 next meets Dec. 4-5 in Dallas, Texas. For meeting or membership details, contact Staff Manager Jim Olshefsky, ASTM (610/832-9714). //

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