Mould and damp in UK housing is a persistent issue. Ranging from structural damage to serious health concerns, the repercussions can be catastrophic. But to combat the issue, the root cause must be addressed: thermal bridging. In this article, Dr Alex Boote, Product & Innovation Manager at ARC Building Solutions, discusses the importance of eliminating thermal bridging when retrofitting insulation.
As energy costs rise and net zero targets edge closer, the demand for warmer, more efficient homes has never been greater. More than a fifth of the UK’s carbon emissions stem from homes with poor energy efficiency, so upgrades, such as retrofit insulation, are the key to unlocking more sustainable homes offering an enhanced quality of living.
But when retrofitting insulation, it must be done to a high-standard and correctly, otherwise it can worsen thermal bridging – leading to heat loss and potential moisture problems, and ultimately dangerous damp and mould. The government recognises this by largely investing in retrofit training through the launch of its Warm Homes Skills Programme, where training providers across England can apply for financial support to fund accredited courses. This programme was put in place to support the delivery of the government’s most recent grant, the Warm Homes Plan, which provides funding to low-income households and renters to improve home energy performance and reduce heating costs.
While government funding is a positive step, it is essential that retrofit work is carried out to a high standard to ensure the grants deliver on their intended impact. Poor retrofitting of insulation can lead to thermal bridging, which commonly occurs when there is a localised weakness or a discontinuity in the insulation. This creates or worsens cold spots, reducing the overall effectiveness of the insulation and undermining any previous retrofit efforts.
Thermal bridging is particularly common at the eaves junction, the joint between the roof and the wall. Poor insulation at the eaves can lead to the formation of cold spots, resulting in condensation and damp. The moist air produced from exhalation, cooking and cleaning naturally goes toward colder areas, and when it meets these thermal bridges the water vapour condenses, creating the ideal environment for mould to grow. Damp and mould will not only damage a building’s structural health, but it also poses a serious risk to occupants’ wellbeing, potentially leading to respiratory complications – and in the worst cases, death.
But still, the eaves junction is all-too-often overlooked during retrofit. The difficulty in accessing and properly insulating the area results in inadequate thermal insulation, exacerbating the chances of thermal bridging occurring. This then converts into major heat loss, high energy bills and detrimental health risks due to mould and damp growth.
Historically, the eaves junction would typically be insulated by stuffing glass wool into the area. However, this method blocks the crucial ventilation path, resulting in condensation build-up in the loft space, which contributes to the problems we are seeing in many British homes. While some installers will attempt to estimate a ventilation gap, it is difficult to ensure the appropriate path is maintained over time.
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PAS2035, the framework for retrofit standards, specifies government-funded retrofit projects require thermal bridges to be addressed. So, it is essential to specify the correct retrofit products to meet these standards. Today, there are innovative products on the market with built-in ventilation trays to ensure the necessary ventilation in the loft space is maintained, discouraging the formation of damp and mould while maintaining the building’s thermal envelope.
This framework plays a significant role in ensuring retrofit quality and delivering a higher standard of energy efficiency. Although the eaves detail may seem like a minor area, its impact on the overall comfort and health of a home really is significant. Thanks to recent innovations in retrofit design, this problem can easily be addressed, as today energy upgrades are manufactured to provide ease of installation with these new frameworks in mind.
By proactively addressing the challenges of thermal bridging and improving eaves junction insulation, installers will not only be meeting regulatory regulations but also supporting the UK’s broader goal of reducing carbon emissions and becoming net zero by 2050. Eliminating thermal bridging in the future housing stock is the key to creating healthier, more energy-efficient homes.
Discover ARC’s retrofit range: retrofit for warm safe homes – ARC Building Solutions
