The Importance of Using Traditional Lime-Based Mortars in Heritage Masonry Restoration

In 2024, Lennox Masonry restored the city hall in Duncan, BC using traditional lime-based mortars.

In this blog post, Lennox Masonry of Victoria, BC discusses the necessity of matching old lime-based mortars when restoring historical and heritage masonry buildings

Restoring heritage masonry buildings is not only about maintaining their aesthetic appeal—it’s about preserving their history, structural integrity, and ensuring they stand for generations to come. One of the most critical elements in achieving this is the use of traditional lime-based mortars. Here’s why they matter so much in heritage restoration:

Breathability and Moisture Management

Lime mortars are naturally breathable, allowing moisture to escape from the masonry. This breathability prevents moisture from becoming trapped within the walls, which can lead to deterioration of both the mortar and masonry units, creating structural damage. Cement-based mortars, by contrast, are much less permeable and tend to trap moisture—often worsening the very problems restoration seeks to solve.

Lime mortar is elastic and thus flexible, which allows it to accommodate for large and slight movements in the masonry structure, recombining when needed through a self-healing process. This characteristic is paramount when it comes to the preservation of heritage structures, as it helps eliminate moisture-related issues that are introduced into the building once gaps in the masonry start forming. This brings us to our next point...

Flexibility and Accommodation of Movement

Historic masonry buildings often settle and move slightly over time due to changing temperatures, moisture, or shifts in their foundations. Lime mortar’s flexibility allows it to accommodate minor movements without cracking, protecting both the mortar and the surrounding masonry units. Modern mortars, which are rigid and hard, can crack and cause further damage to the historic stone or brick.

Compatibility with Historic Materials

Most heritage masonry buildings were originally constructed with lime-based mortars. Using traditional lime mortars for restoration maintains the building’s authenticity, ensuring that repairs are compatible with the original structure. This prevents damage from incompatible materials, such as Portland cement, which can be too hard and impermeable for older masonry.

The key here is to ensure that the mortar is going to expand and contract during the freeze and thaw cycles at the same rate in relation to the surrounding stone and/or brick. This can only happen if the same mortar is being utilized.

Reversibility and Conservation Principles

Lime mortars can be removed without damaging the original stone or brick due to their soft character, even after years of compression. The use of conservation-friendly tools are also necessary during the repointing process. Using lime-based mortars while repointing heritage masonry structures aligns with the principles of conservation, allowing future repairs without harming the historic fabric.

Aesthetics and Authenticity

Authentic restoration requires materials and techniques that reflect the original construction. Lime mortars offer a natural, historic appearance, blending seamlessly with traditional stonework and maintaining your building’s character. When done properly, repointing or even rebuilding certain aspects of heritage masonry buildings can appear seamless from the old to the new.

Sustainability and Environmental Impact

Lime-based mortars are produced with not only a lower carbon footprint compared to modern cement, but are actually carbon-negative. During the setting process, lime mortars reabsorb the carbon dioxide produced during their creation. They’re also biodegradable and made from natural, renewable materials—making them an excellent choice for responsible restoration.

Self-Healing Properties

Lime mortar can self-heal small cracks due to its slightly water-soluble nature, which allows it to reseal hairline fissures over time. This unique property helps prolong the life and durability of heritage masonry walls.

Avoiding Common Restoration Mistakes

The use of modern cement mortars in historic buildings can lead to a host of problems, including trapped moisture, accelerated decay, and irreversible damage. Modern mortars are too hard for traditional masonry—original bricks or stones can break before the mortar does, leading to costly repairs and lost heritage value.

Conclusion

For anyone involved in the restoration of heritage masonry buildings—whether you’re a homeowner, builder, or conservationist—traditional lime-based mortars should always be your first choice. Their breathability, flexibility, compatibility, and sustainability not only preserve the structural and aesthetic integrity of your building, but also honor its history.

By choosing lime-based mortars, you’re investing in the longevity, authenticity, and environmental stewardship of Canada’s architectural heritage. If your project needs guidance or hands-on expertise, Lennox Masonry is passionate about restoring heritage buildings the right way—using time-tested materials that let your building breathe and endure. With dozens of completed heritage masonry projects throughout Victoria, BC and Duncan, BC, we are a trusted, professional, and knowledgeable masonry company when it comes to the conservation of masonry buildings..

Preserve the past. Build for the future. Choose lime

Lennox Masonry of Victoria, BC has been proudly serving both Vancouver Island and the Gulf Islands for over a decade. We are small group of skilled masons with a great deal of passion towards our trade and for improving the communities we live and work in. We extend our gratitude to the lək̓ʷəŋən people for allowing us to share and work on this corner of the garden with them. We are thankful for the residents and businesses of Victoria, BC for supporting us in our endeavors!

If you’re in need of a professional and reliable masonry company for your next project, please contact us today! And check out our Project page for inspiration when it comes to your next masonry idea!