limeplaster

Lime plaster is a traditional plastering material that uses lime as the binder, combined with inert aggregates such as sand. It is applied to interior and exterior walls and is valued for its breathability, elasticity, and compatibility with historic masonry. Unlike cement-based plasters, lime plaster cures by carbonation, gradually drawing carbon dioxide from the air as the lime binder hardens.

Traditional lime plaster is usually made from lime putty mixed with sand and water. When hydraulic lime is used, natural pozzolanic materials or clay impart early strength and water resistance. Limes can be categorized as non-hydraulic (putty-based) or hydraulic lime, and finishes can range from a smooth plaster to textured coats.

Application typically proceeds in coats: a scratch coat to provide a key, a brown or middle coat, and a final finish coat. Typical thickness ranges from about 10 to 20 millimeters overall. Substrates should be sound, clean, and dampened before application to improve bond.

Curing is slow and depends on moisture availability; excessive drying or frost can cause cracking. Lime plaster remains relatively susceptible to water ingress unless combined with appropriate limewash or protective finishes and is usually replaced or repaired with matching lime mortars to maintain breathability.

Uses: Widely employed in historic restoration and new-build projects aiming for a traditional appearance, lime plaster supports building physics by allowing vapor and moisture movement. Exterior finishes are often completed with limewash or a breathable topcoat to protect while preserving porosity. Lime plaster is part of broader lime-based masonry systems and is often paired with limewash for exterior protection and aesthetics.