Cavity Wall Tie Survey

An on-site inspection will be carried out to inspect and assess the condition, type, and effectiveness of the existing wall ties to all accessible external cavity walls. 

In order to confirm the condition of the wall ties, sample ties will be located at random to each elevation through the use of metal detection. Once located, a small hole will be carefully drilled, usually through the outer leaf between the brickwork, to allow the insertion of a boroscope camera into the cavity. In most cases, the ties can be viewed and examined without the need for further invasive measures. Of course, these holes will be repaired before leaving site.

When wall tie failure has been identified, a remedial wall tie installation will be advised in order to reinstate the compromised structural stability. Often, a failing wall tie system will have led to cracks and bulges in the masonry wall. In these cases recommendations will include suitable masonry repair techniques, as well as preventive measures aimed at the potential for the existing ties to continue causing any further damage.

The importance of wall ties lies in the potential consequences of their failure

In recent years, the severity of wall tie failure has become increasingly apparent. Consequently, it has become commonplace for home buyer reports to recommend a wall tie survey not only on properties that exhibit visual indicators of wall tie failure, but also on cavity built properties constructed prior to 1981, before the standard of protective wall tie coatings were increased.

The purpose of these ties are to connect the inner and outer layers of a wall together, providing stability and structural support. Wall ties were commonly constructed from mild steel and featured a protective outer coating. However, over time, this protective layer can deteriorate, leaving the steel vulnerable to moisture from external masonry and leading to corrosion. In addition to mild steel, wall ties were also made from materials such as stone and slate, which are particularly prone to damage from vibrations caused by construction activities, passing traffic, or ground movement. These vibrations can compromise the integrity of the ties, causing them to lose their bond with the structure. The first signs of failure include bulging or bowing walls and stepped or horizontal cracking between the masonry.

If your property displays any of these issues I would advise you to have a wall tie survey carried out. For example, the corrosion of thick steel ties, prevalent in older housing stock across Britain, can lead to extensive damage if left unaddressed. Corrosion causes the ties to expand, exerting pressure on the surrounding masonry, initially resulting in horizontal cracks (as pictured) and eventually leading to the separation of the outer leaf into unsupported sections. As each row of corroding ties lifts the outer leaf incrementally, it places pressure on the roofline, leading to the "pagoda effect" or the buckling and potential collapse of the outer leaf. These outcomes can result in significant repair costs.