Lime plaster is an eco-friendly, traditionally formulated wall plaster used in historic buildings for centuries. Made using lime as the binder rather than cement or gypsum, it forms a breathable surface that lets moisture move through the wall.
Image shows lime earth coloured limewash.
The breathable quality of this material is one of the reasons lime plaster was widely used in older buildings constructed with solid stone or brick walls. Unlike modern plasters that can trap moisture, lime plaster helps regulate humidity within the building fabric.
For homeowners restoring older properties, understanding how lime plaster works and how it can help keep your home healthy and damp free is vital. Using compatible materials helps maintain the natural behaviour of traditional walls and can prevent problems such as trapped damp or failing finishes.
What is Lime Plaster?
Lime plaster is a mineral plaster made using lime, sand and water. The lime acts as the binder, holding the aggregate together to create a durable wall surface.
Unlike gypsum or cement plasters, lime plaster remains vapour permeable. This means moisture vapour can pass through the plaster rather than becoming trapped within the wall.
Lime plaster walls are common in traditional buildings built before the widespread use of cement in the late nineteenth and early twentieth centuries. Many Georgian, Victorian and earlier properties still retain lime plaster internally.
Because of its breathable properties, lime plaster continues to be used today in conservation work and traditional building restoration. Many owners of period properties are removing non breathable cement based plasters and renders, and reinstating traditional lime based building materials.
Lime Plaster Ingredients
Traditional lime plaster is made from simple natural ingredients, typically a mix of lime, sand, and water.
In some traditional plasters, natural fibres such as cow or horse hair were also added to improve strength and flexibility.
The lime binder gives the plaster its characteristic breathability and flexibility. As the plaster dries, the lime slowly reacts with carbon dioxide in the air through a process known as carbonation, gradually hardening into a durable mineral surface.
The History of Lime Plaster
Lime plaster has a history dating back thousands of years. Its use has been documented in Roman and Egyptian buildings, and it was also used to construct the Great Wall of China.
Before the development of modern cement and gypsum plasters, lime was the most common binder used in building materials.
Lime plaster was widely used on internal walls in historic buildings because it worked well with the other traditional materials used at the time, like solid stone walls, brick, lime mortars and timber building frames.
The earliest evidence of lime plaster being used dates back to around 7000 BC in parts of the Middle East. Ancient builders discovered that heating limestone produced a reactive material that could be mixed with water and sand to create a durable plaster finish.
The Romans refined lime technology significantly, developing different plaster mixes and incorporating materials such as volcanic ash to improve strength and durability. Roman lime plasters were often used not only as wall finishes but also as the base for decorative frescoes and painted interiors.
Throughout the medieval and Georgian periods, lime plaster remained the standard interior finish across much of Europe. Craftsmen developed multi layer plaster systems that could produce extremely smooth surfaces for decorative work such as mouldings, cornices and ornamental plaster ceilings.
It was only in the late nineteenth and early twentieth centuries, with the widespread adoption of cement and later gypsum plasters, that lime plaster gradually fell out of mainstream use. Today it remains an essential material in the conservation and restoration of traditional buildings.
Why Lime Plaster is Returning to Period Properties
The biggest reason lime plaster is being reinstated in period property renovations is its ability to regulate moisture within traditional walls. When humidity rises within the wall, moisture can evaporate through the plaster surface. When conditions become drier, the wall gradually releases stored moisture.
This natural moisture buffering helps stabilise the internal environment of older buildings and is still one of the most effective ways to keep damp out of old buildings. In solid wall properties such as stone cottages and brick terraces, it allows the building fabric to breathe rather than trapping moisture inside the structure.
As many homeowners discover during renovation work, introducing impermeable materials such as cement plasters or modern vinyl paints can disrupt this balance. Returning to breathable materials like lime plaster helps restore the way traditional buildings were designed to manage moisture.
Lime Plaster vs Gypsum Plaster
Modern buildings typically use gypsum plaster rather than lime plaster. While gypsum is suitable for many modern construction methods, it behaves differently from traditional lime materials.
Lime plaster is vapour permeable, allowing moisture vapour to pass through the wall surface. It is also slightly flexible, which helps it accommodate small structural movements in older buildings.
Gypsum plaster, by contrast, sets quickly and forms a denser surface. Although this makes it convenient for modern construction, it does not provide the same level of vapour permeability as lime plaster.
In buildings designed with breathable wall systems, replacing lime plaster with gypsum or cement based materials can sometimes lead to moisture becoming trapped within the wall structure.
For this reason, lime plaster is often recommended when repairing or restoring traditional solid wall buildings.
Painting Over Lime Plaster
Lime plaster can be painted, but the type of finish used is important. Because lime plaster is breathable, any paint or decorative coating applied over it should also allow moisture vapour to pass through the surface.
Using impermeable paints can restrict this movement of moisture. In older buildings with solid walls, this may lead to damp patches, peeling paint or deterioration of the plaster surface over time.
Common breathable finishes used on lime plaster include:
Limewash
A traditional finish made from lime and water. Limewash is extremely vapour permeable and has been used for centuries on lime plaster walls in historic buildings.
Lime paints
Modern lime paints are based on similar mineral ingredients but often offer improved durability and coverage compared with traditional limewash.
Mineral paints
Some modern mineral paints are specifically formulated to remain highly vapour permeable while providing a more durable interior finish.
Clay Paints
Clay paints may also be suitable for lime plaster where vapour permeability is required.
Using breathable paint supports the moisture regulating properties of lime plaster walls.
Is Lime Plaster Still Used Today?
Although modern plasters are now common in new construction, lime plaster is widely used in conservation and restoration work and some eco builds. It’s seeing a resurgence in popularity due to it’s superior performance in terms of breathability, damp resistance, and flexibility.
Heritage buildings often rely on breathable materials to function properly. When repairing older properties, lime plaster can help maintain compatibility with the existing building fabric.
Many homeowners restoring traditional properties are now rediscovering lime plaster as part of a wider approach to using breathable materials that support the long term health of the building.
Need Advice?
Want advice on using and decorating lime plasters? Our friendly team of paint experts will be delighted to help. Contact us for advice.
