Work Item
ASTM WK82156
Revision of C926-21 Standard Specification for Application of Portland Cement-Based Plaster
Rationale
The ballot item captures three key rationale points:
1. A V-groove is an acceptable alternative to a physical separation at dissimilar materials.
2. The term dissimilar materials is often misunderstood and misconstrued. We are currently experiencing a rash of misinterpretations that have plasterers having to isolate stucco from all sorts of mis-perceived dissimilar materials, including casing beads and weep screeds. Technically, PVC, fiberglass, galvanized steel and zinc are all dissimilar materials; yet we couldn’t plaster without lath and some accessories. Plaster is not going to bond to these materials and a separation will naturally occur via plaster shrinkage.
3. The proposed language establishes that components of the plaster assembly (such as lath and accessories) are not to be construed as dissimilar materials. The proposed language also recognizes proprietary products that are manufactured in a manner to directly receive plaster and are therefore exempt from the requirement.
Work Item Status
Date Initiated: 06-09-2022
Technical Contact: Matthew Innocenzi
Item: 002
Ballot: C11.03 (22-04)
Status: Negative Votes Need Resolution