Repointing an old house is an essential part of maintaining the structure, and it involves replacing old or deteriorating mortar between the bricks or stones. Over time, weathering and natural wear can cause the mortar to weaken, leading to cracks and gaps. This leaves the structure vulnerable to moisture, which can cause further damage. While traditional cement-based mortar is often used, lime mortar has become a popular choice for repointing older buildings, especially those with historical or heritage significance. If you’re asking yourself, “Should I repoint my old house with lime mortar?” this article will help you explore the benefits and considerations to make an informed decision.
Understanding Lime Mortar
Lime mortar has been used for centuries in the construction of buildings, especially in older structures. Unlike modern cement-based mortars, lime mortar is made from lime, sand, and water. The key difference between lime mortar and cement mortar is how they cure. Lime mortar hardens through a process known as carbonation, which involves absorbing carbon dioxide from the air. This makes lime mortar more breathable than cement mortar, which sets through hydration. The breathable nature of lime mortar is one of the primary reasons it’s preferred for repointing newtownabbey old houses.
Benefits of Using Lime Mortar for Repointing
- Breathability and Moisture Regulation
Lime mortar allows the building to breathe. This is particularly important for older buildings, which often lack modern moisture control methods. Traditional brick and stone walls in old homes have natural porosity, allowing moisture to pass through. Lime mortar enables this moisture exchange while preventing the building’s structure from becoming damp, which can lead to further decay. The breathability of lime mortar helps to regulate the indoor humidity, preventing issues such as mold growth. - Flexibility and Movement
Buildings settle and shift over time, and old houses are often more prone to this natural movement. Lime mortar is more flexible than cement mortar, which can become brittle and crack. The flexibility of lime mortar allows it to absorb slight movements in the structure without breaking. This reduces the need for frequent repairs and ensures a longer-lasting bond between the bricks or stones. - Compatibility with Older Materials
One of the main reasons to choose lime mortar for repointing an old house is its compatibility with older building materials. Many historic buildings were constructed with soft bricks, stones, or other materials that are sensitive to the rigidity of modern cement. When cement mortar is used on these structures, it can trap moisture in the walls, causing damage to the bricks or stones and accelerating deterioration. Lime mortar, being softer and more porous, works harmoniously with older materials, reducing the risk of damage. - Aesthetic Value
Lime mortar has a unique aesthetic appeal that complements older homes. Its natural color and texture blend well with the traditional look of old houses, helping to preserve their historical charm. Lime mortar is also available in a range of colors, allowing you to match the original mortar as closely as possible. This is particularly important for heritage buildings where maintaining authenticity is crucial. - Eco-Friendly
Lime mortar is considered more environmentally friendly than cement mortar. The production of lime produces fewer carbon emissions compared to cement, which is a significant contributor to global warming. Additionally, lime mortar is biodegradable, and it can be safely disposed of, whereas cement is not. If you’re looking for a sustainable option for repointing your old house, lime mortar is a better choice.
When Should You Repoint with Lime Mortar?
Repointing with lime mortar is ideal for older buildings with original brick or stonework. Lime mortar is typically recommended for structures built before the 20th century, as these buildings were originally constructed with lime-based mortar. If you have an old house, especially one built using traditional materials, repointing with lime mortar is often the best choice to maintain the integrity and character of the building.
However, there are some cases where lime mortar might not be the right solution. If your house has been extensively repaired or modified using cement-based mortar, it may not be compatible with lime mortar. In such cases, it might be necessary to carefully remove the old cement mortar before applying lime mortar to avoid issues with adhesion.
Considerations Before Repointing Your House with Lime Mortar
While lime mortar offers numerous benefits, it’s important to consider a few factors before proceeding with the repointing process.
- Cost
Lime mortar can be more expensive than cement mortar due to the materials used and the time it takes to cure. Additionally, lime mortar is more labor-intensive to apply correctly, which can increase the overall cost of the repointing project. However, the long-term benefits, such as the durability and preservation of the structure, can make it a worthwhile investment. - Weather Conditions
Lime mortar needs time to cure, and it is more sensitive to extreme weather conditions compared to cement mortar. It can take longer to set, especially in colder weather. Repointing during the winter months or in very wet conditions could delay the curing process. It’s essential to plan the repointing project during a season with moderate temperatures and minimal rainfall to ensure the mortar cures properly. - Skill and Experience
Repointing an old house with lime mortar is a delicate task that requires skill and experience. Unlike cement mortar, lime mortar can be more challenging to work with, and improper application could lead to issues such as cracking or poor adhesion. It’s advisable to hire a professional with experience in working with lime mortar, especially if you’re dealing with a historic or delicate building. A skilled mason will ensure the mortar is applied correctly and that the repointing is done with care.
How to Repoint Your House with Lime Mortar
If you decide to repoint your old house with lime mortar, the process generally involves the following steps:
- Assess the Condition of the Mortar
Start by assessing the condition of the existing mortar. If it’s loose or damaged, it will need to be removed. You can use a chisel or a special mortar rake to remove the old mortar carefully. - Clean the Joints
After removing the old mortar, clean the joints thoroughly to remove any dust, dirt, or debris. This will help the new mortar adhere better. - Mix the Lime Mortar
Lime mortar is typically mixed in a 1:3 or 1:4 ratio of lime to sand. Be sure to mix the mortar thoroughly to achieve the right consistency. You can purchase pre-mixed lime mortar, or make it yourself with hydraulic lime, non-hydraulic lime, or putty. - Apply the Mortar
Use a pointing trowel to apply the lime mortar to the joints. Work the mortar into the joints firmly, ensuring it is properly compacted. - Tool the Joints
After applying the mortar, use a jointing tool to shape and smooth the joints, making them match the appearance of the original mortar. - Cure the Mortar
Lime mortar needs time to cure. During the curing process, keep the mortar moist by lightly spraying it with water to prevent it from drying too quickly, which can cause cracks.
Conclusion
Repointing your old house with lime mortar can be a fantastic decision, especially if you want to preserve the building’s integrity and charm. The benefits of lime mortar – including breathability, flexibility, compatibility with older materials, and environmental friendliness – make it an ideal choice for many historic homes. However, it’s essential to consider factors like cost, weather conditions, and the level of expertise required before starting the project. If done correctly, repointing with lime mortar can extend the life of your old house and protect it for generations to come.
