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Advice & Sales: 0118 946 9146

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Using Lime Mortar in Conservation Buildings

Conserving old buildings typically requires extensive research, planning and co-operation amongst different groups. One aspect of brick and stone repair that often gets overlooked is the mortar used to fill cracks. It is not surprising that lime mortar is often used on older buildings as it is far more flexible and will not crack when undergoing natural thermal expansion.

In addition, we believe you should choose lime because it is more environmentally friendly than cement. Lime mortar can be used for both restoration of an old building and for making your home look new again.


What Is Conservation?

Conservation is the act of using and protecting resources wisely. To conserve means to protect and save something from being destroyed. The term conservation describes a range of activities that we undertake to care for historic places and objects. This includes buildings, archaeological artefacts, gardens and landscapes. These are often known as heritage assets. Conservation focuses on ensuring continuing use or understanding of these places by current and future generations whilst respecting their original form and function.


Mortar Shouldn’t Be Forgotten When Conserving Old Buildings

The conservation process is an ongoing one, as the preservation of historic buildings involves continuous learning and adaptation to new knowledge. Building conservation is more than just restoring the bricks and mortar of a structure, it’s about preserving the building as a whole. The forgotten aspect is often the mortar of the building… the glue that holds the structure together. 

The use of lime plaster for construction and conservation purposes can help ease environmental concerns. It is sustainable, repairable and carbon neutral. Although lime plaster was once used on historic buildings, it has been supplanted by a newer material, Portland cement-based plaster. This new form has caused significant damage to many historic structures.


Structural Movement Concerns

As older buildings are often built on poor foundations, they are more prone to movement. During seasonal changes, the conditions of the ground and temperature are likely to change heavily. Solid walls with no cavity mean that during these months the structure will begin to unsettle and likely crack under the pressure.

Lime mortar is a softer and weaker compound than stone and brick, therefore, it bonds easily and can accommodate these slight movements without cracking.


Breathability Using Hygroscopic Action In Your Home

Lime mortar is permeable. This means that it allows water to pass through it, which is good for moisture control in masonry projects. The permeability of lime mortar allows the building to absorb moisture from the surrounding environment. Once this is done, the lime will then release the moisture back into the air when the relative humidity drops. This is called hygroscopic action.

Hygroscopic materials such as lime mortar will stabilise the internal humidity using this breathability feature. The benefit of a breathable home is that breathability helps to prevent cracks in masonry structures. It does this by allowing them to adjust as the environment around them changes. In addition, hygroscopic materials such as lime mortar will stabilise the internal humidity. The result is a more comfortable environment with less condensation and mould growth. This aids in keeping older buildings dry inside without the need for a damp proofing course or any chemical treatments.


Variations Of Lime Mortar You Should Be Aware Of

Lime mortar is a type of mortar that is made from lime, sand and water. Lime mortar can be used to repair brickwork or building materials, as well as being used in construction projects. It is a popular choice for repairing brickwork because it is easy to use, inexpensive and durable. However, there are numerous types of lime mortar:


Hydraulic Lime Mortar

This product is made from Natural Hydraulic Lime (NHL). Hydraulic lime mortar offers a great balance of flexibility and strength. Additionally, this product comes with three varying core strengths that the consumer can choose from, 2, 3.5 and 5 NHL.

Generally, the hydraulic lime mortar will set very quickly and needs wet and damp conditions to reach its strongest. This product works similarly to a cement mortar mix and is the most forgiving for the inexperienced contractor.


Non-Hydraulic Lime Mortar

This lime mortar is made from non-hydraulic lime, commonly known as “lime putty.” This mortar is extremely soft and flexible which makes it perfect for the conservation of delicate masonry. 

It carbonates slowly, making it vulnerable to frost damage in cold conditions. Also, it is ill-suited for any areas where dampness is currently present as the carbonation process may not occur at all in these conditions.


Hot Mixed Lime Mortar

Hot lime mortar, which is made by mixing quicklime with water and adding heat to the mixture, was popular among conservationists because it produced a sticky substance that held bricks together well.



In conclusion, this article has highlighted some of the benefits of using lime mortar in the conservation of older buildings. From preventing mould to keeping the structure dry and secure. Lime mortar is a strong and versatile material that can help restore old buildings back to their former glory. It is a material that has been used for thousands of years and still holds its own today. It is a naturally fire-resistant, breathable material that is flexible when faced with structural movements on poorly laid foundations. Lime mortar is a material that can be easily worked and will ensure your building is more resilient against harsher elements. You can also use lime mortar as an environmentally friendly alternative to cement mortars.

Conservation is a critical component of preserving our cultural heritage. It is an approach that is grounded in respect for the past, informed by research and thoughtful decision-making. It is guided by a desire to make sure that such buildings and monuments are passed on to future generations.

If you are in need of any more information then simply give us a call or contact us via our contact form today!