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Updated in March 2025, this Stucco and Drainage Planes technical document was prepared by the Lath and Plaster Committee of the AWCI Construction Technology Council.
This document provides information on model code language specific to the requirement for a drainage
system or drainage material behind exterior cement plaster (“stucco”) cladding. The text reflects language
found in the following:
- Chapter 25 of the 2021 and 2024 International Residential Code (IRC), and
- Chapter 7 of the 2021 and 2024 International Building Code (IBC).
Chapter 14 of the IBC and Chapter 7 of the IRC contain general information addressing water-resistive barrier (WRB) requirements for all framed exterior wall systems. While the general WRB language applies
to stucco applications, the focus of this document is on new model code language specific to stucco
applications.
This document does not reflect local amendments to or interpretations of model code language. Systems
installed to comply with the requirements of ASTM E119, Standard Test Methods for Fire Tests of Building
Construction and Materials, or NFPA 285 Standard Fire Test Method for Evaluation of Fire Propagation Characteristics of Exterior Wall Assemblies Containing Combustible Components, must be constructed as tested.
Systems also must comply with locally enforced codes, standards and statutes and jurisdictions must adopt model code language using a localized process. The contractor is advised to discern what is locally required for compliance and ascertain any fire-resistive requirements that must be met. Contractors also are urged to confirm the code language enforced on a specific project and if it has been modified to reflect local conditions.
