Over the past two decades, an increasing number of households in the UK have been affected by mould growth, a persistent and widespread issue that poses significant risks to both property and human health. Today, more than ever, preventing mould growth in residential environments has become a national priority, as the consequences of unchecked mould can extend beyond structural damage to deeply impact the physical and mental wellbeing of occupants. Mould growing indoors is not merely a cosmetic issue; it is associated with respiratory problems, allergies, and mental effects among residents. Given the severity of mould, identifying appropriate metrics to assess, monitor, and predict its development in homes is crucial. Reliable assessment tools would enable effective intervention strategies to be implemented, ultimately improving living conditions and safeguarding occupants. The research explored in this study aimed to investigate the complex connections between the occurrence of mould growth and various moisture-related metrics (e.g., indoor relative humidity (RH), vapour pressure excess, etc.). The study uses empirical data collected during heating seasons in households located in the UK, some of them with a documented history of indoor mould contamination. Internal and external RH and temperature levels were continuously monitored, measured, and systematically documented. These data sets provided valuable insights into the environmental factors that contribute to mould growth. The study found a good correlation between mould presence and standardised vapour pressure excess (SVPX). Most rooms with mould had high SVPX levels. This suggests SVPX is more reliable than relative humidity alone for predicting mould.