Interpretation #8025
Published November 16, 2017
Original Request
- Code Version
- 2014
- Code
- RESIDENT
- Code Description
- Chapter
- 3
- Section
- R301.2.1 Wind design criteria and R703.1.2 Wind resistance.
- Topic
- R703.7 Exterior plaster - ASTM C926 and C1063
Question
Is the design and installation of exterior cement based plaster (Stucco) “Deemed to Comply” with R301.2.1 Wind design criteria and R703.1.2 Wind resistance without calculation if it is installed in compliance with the prescriptive provisions of ASTM C926 and ASTM C1063.
Answer Published 11/16/2017 at 9:38 AM
In a typical direct application to a solid surface such as concrete or masonry or application to a lath, the provisions of ASTM C 926 and the code are sufficient. Annex A2, Design Considerations, of ASTM C 926-11a addresses control joints for the relief of stress where metal plaster base is used. The Standard references ASTM 1063 for addressing these issues. Annex A2 establishes the maximum allowable deflection of L/360. The Annex in ASTM C 926a-15a adopted by the FBC-R 6th Edition is expanded somewhat and addresses loads on ornamental features that project beyond the surface of the cement plaster scratch and brown coat assembly such as quoins, bands, and similar ornamentation.
Commentary
None