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 IntroductionCavity 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.  Surveying Cavity walls and Identifying FailuresSpotting problems with cavity wall ties isn’t always easy particularly during ordinary surveys, but the BRE Good Repair Guide 62 provides a roadmap. It starts with looking for signs like cracks or bulging in the outside walls, then using tools like borescopes or metal detectors to check the ties themselves. If you find corrosion, the guide uses a four-point scale to rate the damage:
Causes of Wall Tie DeteriorationWhy do these ties fail? It comes down to the materials and exposure to the elements. Galvanised steel ties, widely used from the 1940s to the 1970s, often had flaws in their protective coating. Those flaws left the steel exposed, and moisture in the cavity sped up the corrosion process. A study in the Journal of Structural Engineering (2017) found that rust on the ties can lead to even more damage. As the rust expands, it causes cracks in the walls, which only make things worse. The study also flagged large-scale housing estates from the post-war building boom—places like the Barking and Dagenham estates (which I was part of a survey team on in 2017-19) was being particularly vulnerable due to rushed construction and lower-quality materials observed in the post war housing boom. This means that even if the percentage of properties impacted is small the impact on the built environment may be catastrophic. Ultimately wall ties failure can result in severe injuries and death. My opinion is that to social housing this may become the new fire and billions is needed to fix the problem. Implications of Wall Tie FailuresWhen wall ties fail, the impact can be huge. The external wall, no longer properly supported, might crack, bulge, or even collapse in extreme cases. The BRE Good Repair Guide 62 stresses that catching the problem early is essential to avoid these outcomes. But if entire housing estates are affected, the safety and financial consequences could be massive. There’s also a financial ripple effect. Many of these homes are privately owned now, thanks to the Right to Buy scheme. That means the responsibility for repairs falls on individual homeowners instead of councils or housing associations. A 2022 report in the Journal of Building Surveying and Construction Safety pointed out that homes with failed ties might become unmortgageable, making them harder to sell and devaluing the property. Mitigation and RemediationFixing failing wall ties involves replacing the old ones with modern stainless steel versions. These new ties are corrosion-resistant and meet today’s standards, like BS 1243:2019. According to BRE Digest 329: Replacing Wall Ties, the process usually includes:
A Potential National CrisisThis issue isn’t small. Estimates suggest that millions of UK homes built between the 1940s and 1980s are at risk because of ageing wall ties. Some experts are comparing this to past crises, like asbestos or the fire safety concerns after Grenfell. If it turns into a widespread problem, the cost of repairs could run into billions of pounds. Recommendations for Homeowners and Industry ProfessionalsIf your home was built between 1940 and 1980, getting a cavity wall survey is a smart move. This is especially important if you’re buying a property or planning major renovations. The BRE Good Repair Guide 62 offers a clear framework for checking wall tie conditions and deciding on next steps. For surveyors and contractors, it’s time to get up to speed on cavity wall tie assessment. The Journal of Construction Surveying Standards (2020) notes that there’s currently no standard qualification for these surveys. Bridging that gap will be essential as demand for these skills rises. ConclusionThe potential failure of cavity wall ties in post-war homes is a problem that’s flying under the radar for many homeowners. But its impact on safety, property values, and repair costs could be huge. Acting early—through proper surveys and repairs—can help avoid a much bigger crisis down the line. As the housing industry braces for what could be a widespread issue, it’s clear that lessons from previous challenges, like asbestos and fire safety, should guide the response. For now, awareness is key. Knowing the history of your home’s construction and getting professional advice when needed can go a long way in protecting your property. About the AuthorJoe Marshall BSc (Hons) Building Surveyor and Director of Silver Teal Ltd With an expansive career throughout London and Southeast England. Joe brings a wealth of expertise to the Silver Teal Workspace. His extensive experience in both public and private sectors, notably in social housing and emergency services, has honed his proficiency in building pathology and the overall built environment. Joe's academic achievements are highlighted by his 1st Class Honours degree in Building Surveying.
As a director, he is a fervent advocate for nurturing young talent and fostering industry growth. Joe is committed to propelling Silver Teal Workspace forward with his visionary leadership. If you would like a complimentary discussion with Joe feel free to get in touch 📞 0208 103 4842 ✉️ [email protected]
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