In regions where the climate experiences freezing temperatures, ensuring that buildings remain structurally sound is a significant challenge. One of the most common issues faced during construction in these climates is frost heaving—where the soil beneath a building freezes and expands, potentially causing serious damage to foundations. To prevent this, a specialized technique known as frost wall or frost protected wall construction is used. This article will explore the importance of frost walls, their types, construction requirements, and how they help protect buildings in cold climates.
The Need for a Frost Protected Wall
A frost protected wall is designed specifically to prevent soil beneath a building from freezing, which can have devastating effects on the building’s foundation. The main objective of constructing such walls is to transfer heat from the building to the soil surrounding the foundation, ensuring that the temperature of the soil stays above freezing.
When soil freezes, the water contained within the soil expands, causing it to push upward. This upward force, known as frost heaving, can damage foundations, leading to structural instability. By preventing the soil from freezing in the first place, frost walls effectively prevent frost heaving and safeguard the building’s foundation.
Frost Heaving and Its Impact on Buildings
Frost heaving occurs due to the freeze-thaw cycle in the soil. Soil consists of voids filled with water and air. In cold climates, when the moisture in the soil freezes, it expands, causing the soil volume to increase. This expansion can push up on any structure resting on the soil, including the building foundation, causing uneven settlement and structural damage.
The expansion of water into ice forms what is known as an ice lens—a layer of ice beneath the soil that pushes the surrounding soil upwards. As this ice expands and contracts with temperature fluctuations, it can cause significant pressure on the foundation above. If not properly addressed, this pressure can result in serious cracks or even cause the building to shift.
Thus, preventing frost heaving is crucial for maintaining the structural integrity of buildings in freezing climates, and the construction of a frost wall is a reliable method to achieve this.
What is a Frost Wall?
A frost wall is an insulated wall constructed around the periphery of a building’s foundation to protect it from the effects of freezing soil. These walls are typically installed below the frost line, which is the depth at which the soil freezes during winter. By placing the wall beneath the frost line, the foundation is shielded from the upward pressure caused by frost heaving.
In addition to being built below the ground, frost walls can also be installed above ground within the building’s structure. These walls serve as insulation to help maintain warmth inside the building, which in turn helps prevent the surrounding soil from freezing.
Frost walls can be constructed as either load-bearing or non-load-bearing, depending on the needs of the building and the region.
Types of Frost Walls
Frost walls can be classified into two main types based on their function and the requirements of the building:
1. Load Bearing Frost Walls
Load-bearing frost walls are designed to support the weight of the building, acting as a foundation wall itself. These walls are placed deep beneath the soil, below the frost line, to ensure that they are not affected by frost heaving. Load-bearing frost walls are typically used in regions with extremely cold temperatures, where the ground freezes deeply.
The wall not only acts as a foundation but also serves to insulate the building from the surrounding soil. In cold climates, these walls are critical in ensuring the long-term stability of the building.
2. Non-Load Bearing Frost Walls
Non-load bearing frost walls are primarily used for insulation purposes. They do not support the weight of the building but instead help prevent heat from escaping through the foundation. These walls are usually built inside the building and do not come into contact with the exterior walls. A small gap is typically maintained between the two walls to allow for proper insulation and ventilation.
These walls are commonly used in buildings that do not have heating systems, as they help to keep the building warm by preventing heat loss through the foundation. Special care must be taken to avoid moisture buildup between the walls, as trapped moisture can freeze and cause structural damage.
Requirements for Frost Wall Construction
To ensure the effectiveness of a frost wall, several requirements must be met during its construction:
- Sealing Basement Walls: The basement walls should be properly sealed to prevent gaps through which moisture could enter. If the walls are made of cinder blocks, the gaps between them should be filled with brick fillers or a similar material. If concrete is used, cracks should be sealed with specialized paint to prevent moisture penetration.
- Prevention of Moisture Penetration: The entire structure, including the frost wall, must be constructed with a primary focus on preventing moisture from entering. This is especially important in freezing climates, where moisture can quickly turn into ice, causing cracks and other issues in the foundation.
- Proper Insulation: Insulation is critical for frost walls, especially for non-load-bearing walls. The insulation must be placed both vertically around the exterior of the foundation and horizontally along the basement of the foundation. Rigid foam insulation is commonly used, as it is effective in retaining heat and preventing heat loss.
Applications of Frost Walls
Frost walls are particularly useful for protecting foundations in freezing climates. There are two primary applications of frost walls:
1. Protection of Shallow Foundations
In areas where deep foundations are either impractical or not cost-effective, non-load-bearing frost walls can be used to protect shallow foundations from freezing. These walls are constructed around the foundation, leaving a small gap to ensure that heat radiated from the building warms the surrounding soil.
To enhance insulation, rigid foam is placed around the foundation both vertically and horizontally. This arrangement prevents the soil from freezing by keeping the warmth within the ground, thereby preventing frost heaving.
2. Frost Wall for Non-Heated Buildings
For non-heated buildings, the frost wall serves a slightly different purpose. In these cases, a horizontal layer of insulation is laid beneath the entire foundation area. This layer extends outward beyond the building, effectively preventing the soil from freezing by trapping warmth within the ground. No vertical insulation is required in these cases, as the goal is to maintain ground temperature by insulating the soil from the base up.
The insulation layer is typically laid over a gravel bed to help disperse the heat evenly and prevent freezing.
Conclusion
Frost wall construction plays a vital role in ensuring the stability and longevity of buildings in freezing climates. By preventing frost heaving and ensuring that the soil around the foundation remains unfrozen, frost walls protect structures from the destructive effects of freezing and thawing soil. Whether used for load-bearing purposes or simply as an insulating barrier, frost walls are essential for maintaining the integrity of buildings in cold regions.
By understanding the need for frost protected walls, the different types of construction, and their specific requirements, builders and homeowners can make informed decisions about protecting their buildings from the damaging effects of freezing temperatures. Properly constructed frost walls help ensure that buildings can withstand the challenges of extreme climates while maintaining their structural stability for years to come.