Damp, mould, and housing health: progress or persistent problem?

James Berry from the Property Care Association looks at addressing the causes of damp and mould.

The prevalence of mould in our homes is increasing due to factors such as greater airtightness, better thermal insulation, fuel poverty, overcrowding, and the general expectations of modern living. In the past, condensation and mould growth problems were too often, and almost flippantly, dismissed as issues caused by occupancy. Thankfully, we are now seeing the folly of taking this approach, although the circumstances that have brought us here are tragic and unforgivable.

Across society, there is a desire to ensure that damp and mould in our homes are consigned to the past, but despite all the goodwill, there are warning signs that we are not on the right track. Addressing the root causes of damp In reality, curing damp and mould-related problems requires a multifaceted and holistic approach to establish the root cause of the issue.

Consideration of the entire building envelope, occupancy density and style, as well as an understanding of the performance of any building services, is paramount.

Tackling damp in older homes: a complex challenge

Addressing these concerns at the pre-construction phase is comparatively easy, although the gap between designed and real-world performance can differ significantly. Addressing them when working within the confines of an existing structure presents an entirely different set of challenges, where sometimes little is known about the structure, the thermal performance of the fabric, air infiltration rates, and other building factors.

Furthermore, it is widely acknowledged that excessive demand for houses, due to a lack of stock, has increased our tolerance for poor-quality housing. Numerous factors contribute to this, but the reality is that there is no quick, short-term solution to the housing shortage.

Balancing moisture, heat, and ventilation

Understanding how to balance moisture production, insulation, energy input (heat), and ventilation, combined with a good technical understanding of the science of air moisture and condensation, is key to eliminating condensation and mould.

Even with this understanding, curing the problem can be complex, as altering moisture production is often impractical. In many cases, adjustments to heating and ventilation are easier than controlling moisture production, particularly when there is no obvious excessive source of moisture. Ventilation strategies, moisture production, and heat input typically require some input from the occupants, yet residents are often given little to no guidance on how to operate, balance, and maintain these systems.

For example, there is often a misunderstanding regarding the function of trickle vents. Background ventilators, most commonly trickle vents installed in window casings, are an essential component of ventilation systems found in existing buildings.

The intermittent extractor fan should be considered a form of purge ventilation, designed to rapidly remove high levels of moisture or pollutants. Background ventilators, on the other hand, provide “whole dwelling ventilation,” which is essential for: air for breathing; dilution and removal of airborne pollutants; controlling humidity; air for fuel-burning appliances; and temperature control.

Despite the important role they play, trickle vents are too frequently shut, and some are even sealed over concerns about heat loss and drafts, which impacts indoor air quality. A 2019 report by the Ministry of Housing, Communities & Local Government on ventilation and indoor air quality in new buildings showed that only 29 percent of trickle vents were open when they conducted a study on ventilation performance across 80 new build dwellings.

Currently, there is no clear indication of how to educate occupants on the significance of ventilation in maintaining a healthy indoor environment, especially when most media stories focus on conserving heat, creating the mindset that ventilation is counterproductive.

Awaab’s Law

Described as the ‘biggest government reform in a decade affecting social housing,’ the last government tabled amendments to the Social Housing (Regulation) Bill to introduce ‘Awaab’s Law,’ which will require landlords to fix reported health hazards within specified timeframes.

The current government has indicated that they will not only continue with this bill but will look to extend it to private landlords as well. This is unquestionably well-intentioned, but if we are not careful, we could push desperate occupants and homeowners into the hands of unscrupulous opportunists.

Skilled professionals with demonstrable competence in damp diagnostics are certainly not abundant, and there is a huge demand for those currently available. Many will struggle to meet the timeframes being indicated. Ultimately, this could force landlords, in a bid to act quickly, into the hands of “cowboy builders” who are unlikely to provide the correct long-term solution.

Heating

As previously described, ventilation and moisture production are only part of the problem. Heating plays an equal role in maintaining a damp-free environment. Historically, it was advised that we should maintain a constant background temperature in our homes, but the reality is that for the vast majority of the UK population, this is not economically viable.

The issue of heating affordability has been thrust back into the spotlight with the proposed removal of winter fuel payments for all but the poorest pensioners.

It is also worth noting that, according to BRE studies, cold is a greater cause of ill health than damp and mould. This issue is not a simple question of affordability, though. We have an aging and relatively inefficient housing stock, and while retrofit insulation obviously plays a role here, we simply don’t have the workforce or the appetite for it, as the consequences of poor retrofits are becoming more widely understood.

An inevitable increase in occurrence

Homes account for around 15 per cent of the UK’s greenhouse gas emissions through their use of oil and gas for heating and hot water. The government’s plans to tackle this were highlighted in the recent consultation on the Future Homes Standard, which set out the aim for buildings to become even more airtight. This leaves less margin for error when it comes to the provision of adequate ventilation.

The lack of compliant ventilation in dwellings is well-documented, and even within the consultation, there is an acknowledgment that ‘fixed building services are not always installed, commissioned, and (where required) checked to a high standard.’

Going forward

While the growing awareness around damp and mould is a step in the right direction, there is still much work to be done to ensure lasting solutions. The complexity of the issue, especially in existing housing stock, coupled with misconceptions about ventilation, heating, and moisture management, means that progress may be slow and uneven.

Without a more holistic approach — encompassing proper education for residents, skilled diagnostic professionals, and better construction and retrofit standards — the issue of damp and mould will continue to persist. As we look to the future, it is clear that innovation, policy reform, and societal change will all be needed to truly make damp and mould a thing of the past.

It’s time for policymakers, landlords, and residents to collaborate on addressing this widespread issue. Whether through better education, stricter building regulations, or improved ventilation systems, the health of our homes — and the people living in them — depends on it.