Rainscreen Solutions
for Stucco
Prevent Entrapped Moisture. Reduce Cracking.
Modern stucco walls behave differently from those constructed 50 years ago. Newer building materials (like OSB, plastic WRBs) and methods (air sealing, increased insulation, vapor control) reduce the wall’s drying capacity and increase failures from entrapped moisture. Surfactants in Portland cement compromise the water repellence of many WRBs. Creating a continuous, predictable air gap between the scratch coat and the WRB with a rainscreen drainage mat improves the ability of the wall to drain and dry. The air gap enhances the performance of the WRB by eliminating hydrostatic pressure, mitigating risk from fastener penetrations.
Tips for High-Performance Stucco
- Moist cure & follow control joint recommendations to reduce cracking
- At stucco wrapped soffits and insets detail a drainage reveal
- Replace 2nd layer of WRB with rainscreen air gap
- Ventilated weep screed to drain the bottom of the wall
- Vent the rainscreen at the top of the wall to increase drying
Building in the hot-humid southeast?
(Climate zones 1A-3A)? Learn about changes to building codes in the 2018 IBC for stucco and adhered masonry.
EIFS vs Thin Stone with Continuous Insulation
The EIFS industry recognizes that continuous rigid insulation is not a perfect barrier system, and as a result relies on a drainage gap between the foam and the water resistive barrier to drain liquid. A 1/8 inch air gap creates a capillary break to drain liquid water and limits thermal loss. Stucco detailing with continuous rigid insulation take cues from EIFS by having an air gap to drain behind the rigid insulation. A second draining layer immediately behind the stucco is advantageous as well to quickly and evenly dry the stucco, reducing efflorescence and cracking.
Essential Moisture Management Components
for Stucco
