Quelles sont les causes des fissures de seuil sur les murs de briques et la maçonnerie à Montréal?
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What causes sills to crack on brick walls and masonry in Montreal?

Investigating the Root Causes of Sill Cracks in Montreal's Brick Walls and Masonry

Understanding Sill Cracks

In the world of masonry, sill cracks are a common issue, particularly for property owners in Montreal. These cracks typically appear along the sills or ledges at the bottom of windows and doors on a brick or masonry facade. They can pose serious problems, such as water infiltration and structural instability, if left unaddressed.

Common Causes of Sill Cracks

Several factors contribute to the development of sill cracks in brick walls and masonry. Understanding these causes is crucial for both prevention and repair.

Thermal Expansion and Contraction

The primary cause of sill cracks is the natural expansion and contraction of building materials due to temperature fluctuations. Montreal's climate, with its cold winters and hot summers, can be particularly harsh on masonry structures. The constant freeze-thaw cycles can cause brick and mortar to expand and contract, leading to cracks over time.

Structural Settling

Structural settling or movement is another common cause of sill cracks. As a building settles over time, stress can be placed on the walls, causing cracks to form. This is particularly true for older properties in Montreal, where the settling process may have resulted in uneven weight distribution across the foundation.

Water Damage and Frost Heaving

Water is one of the most significant threats to masonry structures. When water seeps into brick and mortar, it can cause substantial damage, especially during the winter when the water freezes and expands, leading to frost heaving. This process can cause the sills to crack and deteriorate over time.

Preventing and Repairing Sill Cracks

The best way to prevent sill cracks is through regular maintenance and prompt repair of minor damage. This includes regular inspection of the masonry, proper waterproofing and insulation, and timely repairs to prevent water infiltration.

When sill cracks occur, it's essential to address them promptly to prevent further damage. Techniques such as tuckpointing, where the damaged mortar is removed and replaced, and the installation of control joints to manage thermal expansion, are often used by masonry professionals like Maçonnerie Montréal.


Sill cracks in brick walls and masonry can be a common issue for property owners in Montreal, primarily due to the city's unique climate and the nature of these structures. By understanding the causes and implementing preventative measures, it's possible to reduce the likelihood of these cracks and maintain the integrity of your property.