013 - What Would You Do If Your Walls Started to Fall? Understanding the Hidden Danger of Failing Cavity Wall Ties

Introduction

​Cavity walls have been common place in construction and have been since the late 1800s. Their implementation in Britain became the go-to method of post-war era construction and continue to be widely used. Although timber frame systems are often used in twenty first century home building due to their cost and time saving benefits they bring generating improved profits for the developers.

​The method of construction grew in application due to the walls superior characteristics. The cavity (air gap) is good at keeping heat in and stopping issues like condensation caused by thermal bridging often observed on traditional solid wall construction. The gap between the internal and external layers of the wall acts as a thermal barrier/break, helping to keep homes warm and dry. According to the BRE Report 262: Thermal Insulation—Avoiding Risks, a well-maintained cavity reduces damp and mould inside the house. Early cavity walls up to the late 1975s were not generally insulated. This upon reflection has left them vulnerable to moisture and overtime may be a hidden pandemic.

Typically the internal leaf of a cavity wall structure is load bearing and the outer portion play a more stability and aesthetic purpose. The two leafs are held together by metal ties ensuring a sturdy structure. Cavity wall ties are metal pieces/clips installed, spanning the cavity, to hold the inner and outer walls together. This in effect should be the only breach in the structure and have been knows to create a potential weak spot. Modern ties are generally stainless steel and designed to hold their integrity far better than their earlier ancestors; however, most ties made in the mid-20th century used galvanised steel. Unfortunately the galvanised coating and manufacturing practices wasn’t always up to scratch, as noted in the BRE Good Repair Guide 59: Understanding Cavity Wall Construction. Over time, exposure to moisture has caused some ties to corrode behind their protective coatings. The occurrence of tie deterioration in a lot of properties has been leading to serious issues and it may be getting worse. 

As observed the front of your house could just fall off which it isn’t suppose to do.


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