Lime plaster is found in traditional buildings, and is increasingly being reinstated into period properties. Unlike modern gypsum or cement plasters, lime based materials absorb and release moisture naturally, helping regulate humidity within the building fabric.
Image: Graphenstone heritage paints range.
Because of this, choosing the right paint for lime plaster is important. Many conventional paints contain acrylic binders that form a relatively impermeable film on the surface. When applied over lime plaster, these coatings can slow vapour movement and trap moisture within the wall.
The best breathable paint for lime plaster allows moisture vapour to pass through the surface while still providing a durable decorative finish. Mineral paints and lime based coatings are typically the most suitable options. However, a tin of paint claiming to be breathable does not mean it’s suitable to use with lime plaster.
This guide explains which paints work best on lime plaster walls, and how to understand which paints are truly breathable.
Can You Paint Lime Plaster?
Yes, lime plaster can be painted, but the coating must be a suitably breathable paint.
Lime plaster is a highly breathable substrate. It regulates moisture by allowing water vapour to move through the wall structure. If the paint applied over it blocks this process, moisture can become trapped between the plaster and the paint film. Over time this may lead to blistering, peeling paint or damp patches.
Mineral paints, lime paints and other vapour permeable finishes allow moisture to evaporate naturally without damaging the plaster beneath.
Understanding Sd Values and Breathability
The breathability of a paint is commonly measured using its Sd value, which indicates how resistant a coating is to water vapour. The Sd value represents the thickness of still air that would provide the same resistance to vapour movement as the paint film.
In simple terms, the lower the Sd value, the more breathable the coating.
Breathability is often grouped into four broad classes:
Sd Class 1- Highly Breathable (sd < 0.14 m)
Paints in this category allow water vapour to pass through very easily. These finishes are generally the most suitable for lime plaster and other traditional building materials where moisture needs to evaporate freely.
Sd Class 2 - Moderately Breathable (sd 0.14 – 0.5 m)
These coatings still allow a reasonable amount of vapour movement, but offer less permeability than highly breathable mineral finishes.
Sd Class 3 - Limited Breathability (sd 0.5 – 1.5 m)
Paints in this range restrict vapour movement more significantly and may not be suitable for older solid wall buildings where moisture regulation is important.
Sd Class 4 - Low Breathability (sd > 1.5 m)
These coatings form a much more impermeable film and can trap moisture within the wall structure. They are generally not recommended for lime plaster or other breathable wall systems.
When decorating lime plaster walls, choosing coatings with very low Sd values helps preserve the breathable behaviour of the plaster and allows traditional solid wall buildings to manage moisture naturally.
Best Breathable Paints for Lime Plaster Walls
Several types of breathable paint can be used on lime plaster, but here’s our personal top picks that offer breathability, durability, and a range of attractive finishes!
Graphenstone GCS Interior
Graphenstone GCS Interior is a breathable lime, silicate, and mineral based interior paint designed for walls and ceilings in modern living spaces. It’s available in a wide range of attractive colours.
The coating provides a durable decorative finish while offering high breathability. The paint has an Sd value of ≤0.04 m, placing it firmly in the highly breathable category.
This allows moisture to pass through the paint film so lime plaster can continue regulating humidity within the wall.
GCS Interior also has very low VOC emissions (<1 g/L) and a mineral alkaline formulation with a pH of around 11, making it suitable for mineral substrates such as lime plaster.
Unlike traditional lime paints, mineral interior paints such as GCS Interior are also highly durable and washable, achieving Class 1 washability under EN 13300.
For many interiors this makes it one of the most practical breathable paints for lime plaster walls, particularly where a full colour range and a durable finish are required.
Graphenstone Ambient Pro
Graphenstone Ambient Pro is a lime based mineral paint formulated using aerated lime, and is available in a selection of colours.
Because the binder is lime, the coating is chemically compatible with lime plaster and other mineral substrates. It provides a highly breathable decorative finish and high breathability, with an Sd value of ≤0.05 m.
Ambient Pro also has a highly alkaline composition (pH around 13), which is typical of lime based coatings and contributes to natural resistance to mould growth.
This paint also has a photocatalytic formulation, which can help break down airborne pollutants such as nitrogen oxides and VOCs when exposed to light. It's available in white and a limited selection of soft colours, making it suitable for interiors where a mineral lime finish is preferred.
Auro 344 Lime Paint
Auro 344 is a traditional lime paint made with calcium hydroxide, mineral fillers and titanium dioxide. It’s available in white only.
It is highly vapour permeable with an Sd value below 0.05 m, allowing lime plaster walls to release moisture naturally.
Auro 344 is a mineral coating with trace VOC content, making it a low emission option for traditional interiors. It dries to a soft matt finish with the characteristic chalk appearance often associated with historic limewashed walls.
Traditional lime paints are particularly well suited to heritage buildings and restoration projects where breathable mineral finishes are preferred.
Can You Use Standard Emulsion on Lime Plaster?
Many modern emulsions contain acrylic or vinyl binders that create a flexible plastic film on the surface.
Although some of these paints are marketed as breathable, their vapour permeability is often lower than that of mineral paints or lime-based coatings.
On lime plaster walls this can slow moisture movement through the wall surface. Over time this may lead to blistering paint or damp patches where vapour becomes trapped behind the coating.
For this reason, breathable mineral paints and lime paints are usually recommended when decorating lime plaster interiors.
Choosing the Right Breathable Paint for Lime Plaster
The best paint for lime plaster depends on the type of finish you want and how the room will be used.
Need personalised advice about your next project? Contact us, we’ll be delighted to help!
