At PanGro Development, we specialize in restoring and maintaining older buildings. Many of the properties we work on were originally constructed with lime mortar—a traditional mix of lime (hydraulic or non-hydraulic), water, and an aggregate like sand. Using lime mortar offers significant advantages for preserving the integrity of older structures.
What is Mortar?
Mortar is the material that binds together bricks, stones, or tiles in structures such as chimneys, walls, and patios. While modern pre-mixed cement mortars dominate the industry, they are not always suitable for historic buildings. The key challenge lies in the interaction between the mortar and the building materials—be it limestone, granite, brick, or tile.
The Problem with Modern Mortars
Modern high-strength mortars are often "too strong" for natural or older materials, leading to structural issues. A common problem occurs when the modern mortar remains intact while the surrounding stone or brick begins to decay. This degradation is especially noticeable on the exterior of buildings.
Why Does This Happen?
Stone and brick naturally expand and contract with changes in temperature and humidity. In winter, moisture within the stone may freeze, while in summer, it dries out completely. Modern mortar, however, absorbs minimal moisture. This disparity causes stress on the stone or brick causing the material to crumble.
The Solution: Lime Mortar
The good news is that this problem has a time-tested solution: lime mortar. Lime mortar is porous, allowing it to "breathe." This breathability helps the stone or brick and mortar to both expand and contract, creating a more harmonious relationship between the materials. The result is a durable structure that ages gracefully.
Why We Mix Our Own Lime Mortar
While most professionals today rely on pre-mixed mortar, we prefer the traditional method of mixing our own. Historically, the older the building, the less cement was added to the mortar mix. Instead, sand and lime formed the primary components. While lime has some structural limitations, its effectiveness is proven by the millions of lime-built structures still standing today.
There are different grades of lime for various applications. Some limes are designed for structural rebuilding, while others are better suited for plastering, pointing, or similar tasks.
The Cost of Lime Mortar
Currently, lime mortar is more expensive than standard cement mixes. Historically, lime was an affordable material—even shared with agricultural uses—but its specialized nature has driven up costs today. We anticipate that prices will decrease as lime mortar gains popularity and becomes more mainstream.
What Homeowners Should Know
Our primary goal is to educate you, the homeowner, about the importance of using appropriate materials for your home. If your home shows signs of structural deterioration, be sure to discuss the materials being used with your contractor. Using the wrong mortar could exacerbate the problem rather than fix it.
By choosing lime mortar, you can ensure that your home is not only repaired but preserved for generations to come.
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