What Is Cavity Wall Tie Failure?

What Is Cavity Wall Tie Failure?

Cavity wall tie failure can lead to structural damage and even the collapse of an outer wall. It is important to determine if you have a cavity wall and identify the signs of wall tie failure. Wall ties are unseen components that tie the internal and external leaves of a cavity wall together, providing stability and preventing water transfer.

Signs of wall tie failure include horizontal cracks in the outer wall, bulging walls, and damaged window reveals. Wall tie failure can be caused by construction issues such as incorrect spacing or poor quality mortar, as well as corrosion of the ties over time.

The lifespan of wall ties can vary depending on the materials used, with old milled steel ties lasting around 15-20 years and modern stainless steel ties lasting more than 50 years. To prevent wall tie failure, it is important to take preventative measures such as external waterproofing of the outer leaf of the wall. If wall tie failure is suspected, it is recommended to get a professional wall tie survey to assess the extent of the problem and determine the appropriate course of action.

Key Takeaways:

• Cavity wall tie failure can cause structural damage and collapse of an outer wall.
• Signs of wall tie failure include horizontal cracks, bulging walls, and damaged window reveals.
• Construction issues and corrosion are common causes of wall tie failure.
• Old milled steel ties last around 15-20 years, while modern stainless steel ties can last over 50 years.
• Preventative measures like external waterproofing and professional surveys can help prevent and address wall tie failure.

How to Identify Cavity Wall Tie Failure?

To accurately identify cavity wall tie failure, it is important to understand the characteristics of a cavity wall and recognize the signs of wall tie failure. Here are the steps you can take to identify potential issues and determine if a wall tie survey is needed:

1. Confirm if you have a cavity wall: Measure the thickness of the wall using a tape measure. A typical cavity wall will have a thickness of around 270mm to 300mm.
2. Check for a void between brickwork layers: Use a small drill to create a small hole in the mortar joints. If there is a cavity present, the drill bit will penetrate through the first layer of brickwork and stop when it reaches the inner leaf.
3. Look for signs of wall tie failure: The most common signs include horizontal cracks in the outer wall, bulging walls, damaged window reveals, and sagging or lifting lintels. These indicators suggest that the wall ties may have failed or are deteriorating.

If you observe any of these signs, it is highly recommended to seek professional assistance by hiring a structural engineer to conduct a wall tie survey.

“Horizontal cracks in the outer wall, bulging walls, damaged window reveals, and sagging or lifting lintels are all potential signs of cavity wall tie failure.”

Causes of Cavity Wall Tie Failure

There are several causes of cavity wall tie failure that can lead to structural issues in a building. One of the main causes is construction issues during the initial installation of the wall ties. This can include improper spacing of the ties, using ties that are too short, or using poor quality mortar that does not provide a strong bond between the ties and the bricks. These construction issues can weaken the stability of the wall ties over time and increase the risk of failure.

Another common cause of cavity wall tie failure is corrosion. Historically, wall ties were made from mild steel with a galvanized or painted coating. However, these coatings can deteriorate over time, especially in areas with high levels of moisture or exposure to corrosive elements. As the ties corrode, they can expand, causing cracks in the walls and compromising the load-sharing capacity of the structure. The lifespan of wall ties also plays a role in their susceptibility to corrosion. Older milled steel ties typically last around 15-20 years, while modern stainless steel ties can last more than 50 years.

Addressing the causes of cavity wall tie failure is crucial to prevent further damage to the structure of the building. By understanding the construction issues and taking preventive measures, such as using high-quality mortar and proper spacing of wall ties during installation, the risk of failure can be significantly reduced. Additionally, using corrosion-resistant materials for wall ties, such as stainless steel, can greatly increase their lifespan and minimize the risk of corrosion-related failure.

Remedies for Cavity Wall Tie Failure

When it comes to cavity wall tie failure, taking proactive measures is crucial in preventing further damage to your property. One effective remedy is to invest in external waterproofing for the outer leaf of your wall. By using specially formulated masonry waterproofing products, you can create a protective barrier against moisture infiltration, which can help preserve the integrity of your wall ties.

If cavity wall tie failure has already occurred, wall tie replacement is often the recommended solution. There are various types of replacement wall ties available, but it’s important to select the ones that are specifically designed for this purpose. Mechanical remedial wall ties, for example, involve inserting stainless steel rods with expanders into drilled holes to create new ties between the wall leaves.

It’s worth noting that choosing the right wall ties is crucial, as the ones suitable for constructing new walls may not be suitable for replacement purposes. Additionally, if you’re dealing with rendered walls, disguising wall tie replacement can be challenging. However, techniques such as repointing and painting can help minimize the visual impact.

Remember, taking prompt action to address cavity wall tie failure is essential to prevent further structural damage. Whether it’s through preventative measures like waterproofing or the replacement of wall ties, prioritizing the integrity of your cavity walls will ensure the longevity and safety of your property.