wall ties for 200mm cavity

Understanding Wall Ties for 200mm Cavity Walls

Wall ties are essential components in the construction of cavity walls, particularly in structures with a cavity width of 200mm. These ties are used to connect the inner leaf (load-bearing) and outer leaf (weather-resistant) of the wall system, ensuring structural integrity and stability. Their importance cannot be overstated, as they play a crucial role in maintaining the position of the wall leaves and preventing structural distresses associated with moisture ingress and thermal movement.

What are Cavity Walls?

Cavity walls consist of two separate walls (leaves) with a gap (or cavity) in between. This design serves multiple purposes. Firstly, it helps in preventing moisture from penetrating the inner wall, which is particularly important in regions with heavy rainfall. The air gap acts as an insulating barrier, aiding in energy efficiency by reducing heat loss. The 200mm cavity wall is a popular choice in modern constructions due to its effectiveness in enhancing thermal insulation while also providing robustness.

The Role of Wall Ties

Wall ties are typically made from stainless steel or galvanized steel to ensure resistance to corrosion and guarantee longevity. They are installed at regular intervals, and their positioning is crucial to support the weight of the outer leaf and maintain the overall structural integrity of the wall. In a 200mm cavity wall, ties are generally spaced at a distance of about 600mm vertically and 900mm horizontally, although this can vary based on specific structural requirements and local building regulations.

The primary functions of wall ties include

1. Structural Support They maintain the stability of the cavity wall by connecting the two leaves, allowing them to work together to support loads.

2. Movement Accommodation Cavity walls are subject to thermal movement due to temperature changes. Wall ties are designed to accommodate this movement without compromising the structural properties of the wall.

3. Moisture Control By ensuring the two leaves are connected, wall ties help reduce the risk of moisture ingress from the outer layer into the inner wall, thus protecting against potential damage such as mold growth or weakening of the inner structure.

4. Wind Load Resistance In areas prone to high winds, wall ties provide additional anchorage to withstand lateral loads, enhancing the overall durability of the structure.

Installation Best Practices

The installation of wall ties must comply with local regulations and standards. Correct spacing and placement are vital for optimal performance. A common recommendation is to install ties at least 150mm above the damp proof course (DPC) and position them vertically and horizontally at equal intervals. Furthermore, the ties should be embedded into the mortar joint of the outer leaf to ensure effective load transfer and maximize bonding.

Maintenance and Inspection

Regular inspection of wall ties is essential to identify any signs of corrosion or displacement. Over time, environmental factors may lead to wear and degradation, which could compromise the stability of the cavity wall. Any detected issues should be addressed promptly to prevent larger structural problems down the line.

Conclusion

In summary, wall ties play a pivotal role in the construction of 200mm cavity walls. They ensure that the inner and outer leaves work together effectively, providing necessary support while accommodating movement and preventing moisture intrusion. Understanding their function and importance is crucial for builders, architects, and homeowners alike. By following correct installation practices and prioritizing regular maintenance, the longevity and durability of cavity wall constructions can be significantly enhanced, leading to safer and more energy-efficient buildings. As construction techniques evolve, so too will the materials and methods employed in wall tie installation, but their fundamental role in building integrity remains unchanged.