Why Use Lime in Stucco?

History and Features

• Lime-based stucco was used as far back as 9,000 B.C. After the 1930s, lime's popularity waned as Portland cement was added to common stucco products. Lime's natural ability of offering unique light-reflection qualities within the stucco, however, still makes it a modern and appealing choice. Typical application includes three coats of lime-based stucco for a final durable surface, and it can be painted if the natural stucco pigment is not desired.

Increased Hardening

• Lime generates a chemical reaction when exposed to carbon dioxide, and its calcium-hydroxide composition within the stucco mixture activates when applied to a wall. The carbon dioxide in the air near the wall converts the calcium hydroxide into calcium carbonate, which forms a tough and hardened layer across the wall. As a result, small cracks and fissures fill with the stucco, providing a durable protective surface.

Application Benefits

• Lime particles are shaped like tiny plates. This plate structure moves smoothly across the surrounding stucco aggregate, such as sand and small stones. As a result, lime-based stucco moves easily with a trowel during application, creating a consistently smooth surface across the wall.

Water Retention

• Lime has a natural ability for storing water within its particles, and lime-based stucco is thoroughly hydrated even during application. After application, the wall dries more slowly than a stucco based in Portland cement. The slow drying process contributes to less surface fracturing and cracking as the mixture cures.

Substandard Aggregate

• Consumers save money with lime-based stucco because lime mixes well with poor-quality aggregates that are much more inexpensive than premium aggregate, such as from river materials. Lime effectively coats each aggregate particle, creating a strong bond between the two components. Aggregate that is misshapen, or larger than normal, is still an effective component of the stucco, since the lime attachment creates a durable plasticity within the mixture.

Fire Safety

• Lime-based stucco offers a non-toxic material surrounding a building, as well a non-combustible surface. An outside fire that begins to burn the building will be delayed because of the stucco's composition, allowing time for inhabitants to escape.