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February 27, 2025
Cavity Wall Insulation (CWI) has been retrofit installed in approximately 17 million homes across the UK, offering homeowners improved energy efficiency and lower heating costs. However, in recent years, reports from both industry experts and homeowners have highlighted an increasing number of CWI failures, with some suggesting as many as 6 MILLION facing incorrectly installed insulation. Despite its prevalence, the issue has yet to receive the urgent attention it requires.
As the UK faces rising rainfall levels and changing weather patterns, the risk of insulation failure has become more pronounced, leading to significant energy, environmental, and health consequences.
Over the past year, numerous articles have reported widespread issues with incorrectly installed external wall insulation (EWI), resulting in the suspension of 39 firms from TrustMark accreditation. This development prompted a government review committee to address the matter, yet discussions regarding CWI failures remain insufficient.
The increasing feedback from industry professionals indicates that the situation with CWI may be even more widespread and problematic, necessitating greater industry regulation and public awareness. MP Hywel Williams pointed out this fact many times, and again in 2024 where he suggested OSCAR Onsite should play a pivotal role in sorting out this industry mess.
When CWI fails, it can no longer provide the intended thermal benefits, leading to a reduced U-value. This diminished performance not only prevents homes from achieving optimal energy savings but can also result in:
Beyond energy and environmental impacts, failed CWI can cause substantial structural damage to properties:
One of the primary causes of CWI failure is water ingress, which occurs when external moisture penetrates the building envelope and saturates the insulation within the cavity walls. Over the past decade, rainfall levels in the UK have increased by 10%, exacerbating the risk of water infiltration. Properties with compromised weatherproofing—such as damaged brickwork, faulty seals, or defective gutters—are particularly vulnerable. Once moisture breaches the cavity, the insulation’s thermal performance is significantly reduced, leading to accelerated heat loss and increased heating costs.
OSCAR Onsite offers a specialised Cavity Wall Insulation Condition Inspection Survey for homeowners, landlords, local authorities, and housing associations. This survey provides a thorough assessment of both the exterior and interior elements of a property, identifying potential vulnerabilities that may compromise the insulation:
Multi award-winning OSCAR Onsite is the UK’s Leading Authority in Cavity Wall Insulation surveying and extraction, OSCAR Onsite plays a pivotal role in addressing the growing issue of CWI failure. Over the past decade, OSCAR Onsite has trained more than 250 independent insulation firms across the UK, ensuring that professionals follow correct processes, methodologies, compliance standards, and best practices when conducting CWI extraction and clearance. This comprehensive training helps maintain industry standards and ensures that insulation removal is performed safely and effectively.
This program has been designed by OSCAR Onsite with our RICS Partners (Royal Institute of Chartered Surveyors).
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