AC311 - Cementitious Exterior Wall Coatings

Cementitious exterior wall coatings are protective and decorative coatings applied to the outside of buildings, made primarily from cement mixed with other components like sand, lime, fibers, and water. A common example is traditional stucco. These coatings are usually applied over a wire mesh or lath attached to the wall and then troweled to a desired texture.

Once cured, they form a hard, rock-like layer that shields the building from weather and provides an attractive finish. The acceptance criteria for such coatings ensure the mix is formulated correctly (with the proper ingredients and reinforcement) and that it adheres well to the substrate, so it won't crack or fall off under exposure to rain, temperature changes, and other environmental conditions. These systems often integrate with concrete admixtures (AC271) for enhanced performance characteristics.

This acceptance criteria provides a basis for evaluating cementitious exterior wall coating systems that may not be directly covered by existing codes. It establishes testing protocols, weather resistance requirements, and quality standards needed for code approval of these protective coating systems.

• Nationwide acceptance by building officials for stucco and cement coatings
• Streamlined approval process for exterior wall coating systems
• Third-party verification of weather resistance and adhesion
• Enhanced marketability for protective and decorative wall finishes

• ICC Evaluation Service
• AC39 — Walking Deck Waterproofing — Related coating and waterproofing acceptance criteria for building surfaces