Lime Plaster - Traditional, Breathable Coatings for Historic and Solid Wall Buildings

Lime plaster is a traditional mortar based finish composed of lime binder, carefully graded aggregates and water. It sets by carbonation (and, in some formulations, hydraulic reaction) to form a flexible, vapour permeable coating that is chemically and physically compatible with historic masonry. Used internally and externally, lime plaster manages moisture, accommodates substrate movement and accepts breathable finishes such as limewash or mineral paints.

Why choose lime plaster

• Breathability: Allows vapour movement through the wall, reducing trapped moisture and associated decay.
• Flexibility: Tolerates thermal and minor structural movement without brittle failure.
• Compatibility: Matches the softer, hygroscopic behaviour of historic mortars and masonry.
• Repairability: Can be patched with like materials; ages sympathetically with the fabric.
• Aesthetic: Supports traditional textures, profiles and fine tooling for conservation‑sensitive finishes.

Typical uses

• Reinstatement and repair of historic internal and external plaster and render.
• New lime‑based finishes on solid masonry and breathable retrofit work.
• Conservation of decorative mouldings, cornices and textured finishes.

Conservation approach

• Survey and analysis: Record substrate, adhesive condition, moisture/salt profile and decorative stratigraphy.
• Specification and trials: Define binder type/grade, aggregate grading, coat build and produce trial panels for approval.
• Minimum intervention: Prioritise consolidation and like‑for‑like repair; remove incompatible cementitious materials where necessary.
• Controlled application and curing: Apply staged coats by hand, respect recommended thicknesses and curing regimes to ensure proper carbonation and durability.
• Documentation: Provide mix recipes, photographic records, trial approvals and maintenance guidance.