Lime

Intro to Lime

Lime has been used in construction for thousands of years due to its versatility, durability, and natural properties.

Types of Lime

In traditional building, there are three main types of lime: 

Non-hydraulic lime (fat lime) requires air to set and is ideal for dry, breathable applications like plaster and mortar.

Hydraulic lime sets both in the air and underwater, making it suitable for wetter environments.

Quicklime is a highly reactive form of lime used in both processes.

Each type has specific uses, making lime an essential material for restoring and constructing sustainable, long-lasting structures.

Applications

• Plaster

• Render

• Mortar

• Whitewash / limewash

Properties

Lime Plaster, Render & Mortar

Often mixed with sand or animal hair to create a durable plaster, render & mortar for building walls, both inside and outside. 

• Highly breathable, allowing moisture to pass through without trapping it in the wall.

• Eco-friendly made from natural materials, it has a low environmental impact compared to cement-based plasters.

• Durable and can last for many years, often improving with age.

• Flexible, expanding and contracting with temperature and humidity changes without cracking.

• Smooth, natural finish that can be textured or polished. 

• Helps to regulate temperatures inside buildings. 

• The preferred choice when restoring historic buildings and period properties.

• Fire resistant, offering an extra layer of protection. 

• A ‘Self-healing’ property. Small cracks that form over time can slowly close up as the lime continues to carbonate.

Limewash

A whitewash (a lime-based paint) applied to walls, fences, and buildings for both aesthetic and protective purposes. The lime helps kill bacteria and fungi and offers weather-resistant qualities.

• A decorative and protective matte coating with a unique, natural depth, creating a soft, rich, and organic appearance. 

• Anti-bacterial and anti-fungal properties due to its high alkalinity. Effectively preventing mildew and mould growth.

• Resists weathering and can withstand rain and sun exposure better than many modern paints. 

• Sticks well to lime plasters, renders, stone, brick, and similar materials. 

• Highly breathable, preventing the build-up of mould and dampness. 

• Non-toxic with a low carbon footprint compared to synthetic paints. 

Other applications

• Soil amendment

• Water treatment 

• Sanitation & Disinfection

Choosing a Lime

Selecting the right lime product is crucial to the long-term health and durability of a building. The wrong choice can lead to issues such as poor performance, damage to building materials, or compromised structural integrity. Every situation requires careful evaluation based on several key factors:

1. Building Type and Age:

   The age and style of the building influence the type of lime needed. Historic structures, for example, require a lime that is compatible with older materials, ensuring that repairs do not damage or alter the original construction. For modern buildings, considerations like strength and flexibility are important.

2. Environmental Conditions:

   Factors like local climate, exposure to moisture, and the building's location (e.g., coastal or inland) all play a role in the selection of lime. Some limes are better suited for wet conditions, while others may be ideal for drier climates.

3. Type of Mortar or Plaster: The type of work being done—whether it's for mortar, plaster, or rendering—determines which lime product to use. Hydraulic lime, for example, is ideal for environments where moisture exposure is high, while non-hydraulic lime may be better suited for internal work where moisture is less of a concern.

4. Substrate Compatibility: It’s important to consider what materials the lime will be applied to, such as brick, stone, or timber. Certain limes bond better with specific substrates and help prevent issues like cracking, spalling, or poor adhesion.

5. Strength Requirements: Depending on the structural demands of the project, the lime chosen must offer the right balance of flexibility and strength. For example, buildings in areas with high seismic activity may require stronger hydraulic lime, while more flexible, breathable limes may be better suited for buildings that need moisture regulation.

6. Aesthetic Considerations: Lime products can vary in colour and texture. In restoration or heritage projects, the lime used must match the original materials as closely as possible to preserve the building’s historical accuracy and visual appeal.

7. Sustainability and Environmental Impact: Modern considerations often include the environmental impact of building materials. Lime, particularly natural hydraulic lime, is more eco-friendly than cement, but the specific lime chosen should align with the project's sustainability goals.