How Do Masonry Wall Ties Work
Masonry wall ties work by joining the two leaves of a cavity wall together.
They prevent structural issues such as damp penetration, masonry cracks, or collapse of the outer masonry leaf.
Wall ties are made from corrosion and fire-resistant materials, with a drip formation to prevent water passage to the inner leaf.
Modern wall ties are usually made from stainless steel, while composite materials like Ancon’s Teplo range are used for ultra-low energy construction.
Wall ties are installed during construction, pressed into the leaves and surrounded by fresh mortar.
They should span the cavity and have sufficient embedment in the mortar at both ends.
The selection, placement, and spacing of wall ties depend on factors such as the type of masonry, cavity width, building type and height, and geographic location.
Various Eurocodes and Building Regulations govern their correct use.
PD 6697:2010 and BS EN 1991-1-4:2005 provide comprehensive information on wall tie selection.
Did You Know?
1. The concept of masonry wall ties dates back to ancient Egypt, where ropes made of animal hair were used to connect stone blocks in their construction.
2. The first patented wall tie for masonry construction was developed in the United States in 1857 by Dr. Alexander Latta. His design featured a looped wire tie that was twisted together to provide stability.
3. In some cases, masonry wall ties are made from materials other than metal. For example, in historic buildings, wooden pegs or dowels were commonly used as ties instead of metal wires.
4. The function of masonry wall ties is not only to hold the bricks or stones together but also to create an airspace between the inner and outer walls. This airspace provides insulation and prevents moisture from penetrating the structure.
5. The size and spacing of wall ties depend on various factors, such as the type of masonry, the height of the wall, and the location’s exposure to wind and seismic forces. Proper selection and installation of wall ties are crucial to ensure the stability and longevity of masonry structures.
Importance Of Properly Installed Masonry Wall Ties
Masonry wall ties, also known as brick ties, play a crucial role in ensuring the structural stability and longevity of buildings with cavity walls. These ties join the outer and inner leaves of the wall together, preventing separation or collapse. Insufficient or poorly installed wall ties can result in structural issues such as damp penetration, masonry cracks, or even the collapse of the outer masonry leaf.
To fully grasp the importance of properly installed wall ties, it is essential to understand their functionality. In buildings with cavity walls, there is a gap or cavity between the outer and inner masonry leaves. While this allows for insulation and moisture control benefits, it necessitates the use of wall ties to securely connect the two layers of masonry and provide structural integrity. Without reliable wall ties, the outer leaf can detach from the inner leaf, jeopardizing the overall stability of the structure.
To summarize:
- Masonry wall ties, or brick ties, are crucial for ensuring the stability and longevity of buildings with cavity walls.
- Wall ties join the outer and inner leaves of the wall, preventing separation or collapse.
- Insufficient or poorly installed wall ties can lead to structural issues such as damp penetration, masonry cracks, or the collapse of the outer masonry leaf.
- The gap or cavity between the outer and inner masonry leaves in cavity walls necessitates the use of wall ties to securely connect the two layers and provide structural integrity.
- Without reliable wall ties, the outer leaf can detach from the inner leaf, posing a threat to the overall stability of the structure.
Types And Materials Of Masonry Wall Ties
Wall ties are typically made from corrosion and fire-resistant materials to ensure long-lasting performance. One common material used for wall ties is stainless steel, known for its exceptional corrosion resistance and strength. Stainless steel ties do not require additional protective coatings, making them a reliable choice for many construction projects.
In recent years, composite materials have also gained popularity in ultra-low energy construction to prevent heat loss through thermal bridging. An example of such a composite is Ancon’s Teplo range of ties, which are made from pultruded basalt fibers set in a resin matrix. These ties offer excellent thermal efficiency and are ideal for energy-efficient building designs.
The design of wall ties also takes into account the prevention of water penetration. Drip formations are often incorporated to prevent water from passing through the exterior leaf and reaching the inner leaf. This helps maintain the integrity of the wall and prevents water-related issues such as dampness and mold growth.
- Wall ties are made from corrosion and fire-resistant materials
- Stainless steel is commonly used for wall ties due to its exceptional corrosion resistance and strength
- Stainless steel ties do not require additional protective coatings
- Composite materials, such as Ancon’s Teplo range, are gaining popularity for their thermal efficiency
- Teplo ties are made from pultruded basalt fibers set in a resin matrix
- Drip formations are incorporated in wall tie designs to prevent water penetration
- Drip formations help prevent water-related issues like dampness and mold growth.
Considerations For Selecting Wall Ties
The selection of proper wall ties depends on various factors, including:
- The specific type of masonry
- Cavity width
- Building type and height
- Geographic location of the construction project
Eurocodes and Building Regulations provide guidelines for the correct use of wall ties in different situations. These standards ensure that the ties meet the necessary requirements for structural stability and safety.
For most scenarios, PD 6697:2010 provides extensive information and recommendations for the position and density of wall ties. This resource facilitates the selection of appropriate ties based on geographic and topographic factors, eliminating the need for direct involvement from a structural engineer in many cases.
Recommended Density And Placement Of Wall Ties
According to Eurocode 6, the recommended density of wall ties is 2.5 ties per square meter. These ties are typically installed at a horizontal spacing of 900mm and a vertical spacing of 450mm. The density and spacing of wall ties ensure adequate structural support throughout the building.
In addition to the standard density, additional wall ties are required around openings and unbonded edges. Typically, one tie per 300mm of height is recommended in these areas to reinforce the structural integrity and prevent potential issues that may arise from inadequate support.
The length of the wall ties is also crucial. They must be long enough to span the cavity and provide a minimum embedment of 62-75mm in the mortar at both ends. This embedment ensures a secure connection between the two masonry leaves and enhances the overall stability of the structure.
- Eurocode 6 recommends a density of 2.5 wall ties per square meter.
- Wall ties are installed with a horizontal spacing of 900mm and a vertical spacing of 450mm.
- Additional wall ties are needed around openings and unbonded edges, with one tie per 300mm of height.
- The length of wall ties should allow for a minimum embedment of 62-75mm in the mortar at both ends.
“The density and spacing of wall ties ensure adequate structural support throughout the building.”
Additional Factors Affecting Wall Tie Selection And Spacing
The selection and spacing of wall ties can vary depending on the presence of windows, doors, roof verges, and movement joints in the building. These elements create unique conditions that require specific considerations for wall tie placement to maintain structural stability.
When selecting wall ties, it is essential to consider the type of masonry, as different materials may require different types of ties. The building height, cavity width, and geographic location also influence the choice of appropriate wall ties.
To ensure the correct selection and placement of wall ties, it is recommended to consult resources such as PD 6697:2010 and BS EN 1991-1-4:2005. These references provide comprehensive information on wall tie selection, enabling designers, engineers, and contractors to make informed decisions and ensure the structural stability of masonry walls.
In conclusion, properly installed masonry wall ties are vital for the structural stability of buildings with cavity walls. They join the outer and inner masonry leaves, preventing issues such as damp penetration, masonry cracks, and collapse. Wall ties are made from corrosion and fire-resistant materials, with a drip formation to prevent water passage.
- The selection and placement of wall ties depend on various factors, including the type of masonry, cavity width, building height, and geographic location.
- Proper density and spacing, along with the use of specialized ties for specific applications, ensure the structural integrity of the building.
By following industry standards and guidelines, construction professionals can ensure the long-term stability and safety of masonry wall structures.
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Frequently Asked Questions
What are wall ties used for in masonry?
Wall ties in masonry serve a crucial role in ensuring structural stability and connecting various components. These wire or sheet metal devices are utilized to link multiple masonry wythes or attach masonry veneers to a structural backing system. By securely fastening these elements together, wall ties enhance the overall strength and integrity of the structure, preventing potential issues such as separation or collapse. Furthermore, these ties, which are sometimes referred to as veneer anchors in the case of connecting masonry veneers, ensure a cohesive and unified appearance by securely joining the different layers of masonry.
What is the difference between a brick tie and a wall tie?
While wall ties and brick ties are often used interchangeably, they do have slight differences in their functionality. A brick tie is specifically designed to connect two single leaf brick walls together as part of an external wall. It ensures the stability and strength of the bricks by securely holding them together. On the other hand, a wall tie is a more general term that encompasses various types of ties used to connect not only brick walls but also other types of walls, such as concrete or masonry walls, to provide structural integrity and reinforcement. Wall ties have a broader applicability compared to brick ties, as they are not limited to connecting brick walls exclusively.
How are walls tied together?
Walls are interconnected and secured through the use of wall ties. These vital components, typically made of metal, function by spanning the cavity and joining the internal and external walls of bricks together. The ends of the wall ties are specifically designed to tightly lock into the mortar, ensuring a firm and durable connection between the walls. This effective method of tying walls together provides structural stability and enhances the strength and integrity of the overall construction.
How do concrete ties work?
Concrete ties, also known as snap ties, play a crucial role in vertical concrete wall forming. These ties are specifically designed to withstand the lateral forces exerted by fresh concrete. Equipped with two 1″ plastic cones, snap ties not only provide resistance but also help in setting the desired dimension of the wall and covering the plywood hole.
The process of using concrete ties involves placing the ties at regular intervals along the formwork where the concrete will be poured. As the concrete is poured, it exerts pressure on the formwork, and the snap ties help keep the formwork in place by resisting the lateral movement resulting from this pressure. The plastic cones on the snap ties act as spacers, maintaining the precise dimension of the wall while also ensuring that the plywood hole is covered, providing a neat finish to the concrete structure. Overall, concrete ties are an essential component in ensuring the stability and integrity of vertical concrete walls during the pouring process.
