For traditional three-coat stucco, building codes often require two-layers of building paper behind the stucco. The first layer acts as a bond breaker that wrinkles up slightly as the stucco cures, and the second layer acts as the drainage plane.

Synthetic stucco behaves differently, and the manufacturer's installation instructions serve as the code requirement. The instructions may require a drainage approach like the one shown below, or a similar approach using a range of other specialized drainage plane materials.

Cementitious backerboard provides a durable substrate for synthetic stucco. However, the backerboard must be installed over mesh furring strips to provide a drainage gap so that any water that gets through the stucco is directed to weep areas at windows and wall skirts. Manufacturers of synthetic stucco system may require other drainage materials. Consult the ICC technical evaluation report for specific recommendations.
Cementitious backerboard provides a durable substrate for synthetic stucco. However, the backerboard must be installed over mesh furring strips to provide a drainage gap so that any water that gets through the stucco is directed to weep areas at windows and wall skirts. Manufacturers of synthetic stucco system may require other drainage materials. Consult the ICC technical evaluation report for specific recommendations.

In addition, all stucco types need a range of control joints to prevent cracking. For details on these and other critical details for ensuring a durable stucco job, visit the JLC Field Guide.