Image from The Climate Chief
This is the first post in a sequence of three where we review key aspects of how our heritage buildings influence our health and wellbeing: today the focus is on dampness and mould. Typically heritage buildings are those constructed before 1919 characterised with solid external walls – in other words, without a cavity space for an airgap or insulation. The indoor environment has a significant effect upon occupants. Thermal indoor climate, daylight, view, aesthetics and oxygen affect our productivity and wellbeing. In the modern Western World we spend 90% of our time indoors (Ece, 2018, p8), and 60% of that is spent in our homes. Our internal environments should be as pleasant, stimulating and restorative as possible. However internal air quality can be significantly impacted by microbial pollution in our buildings – one of which is mould spores. The World Health Organisation (WHO) reports microbial pollution in internal environments impacts individuals’ health, and in particular the respiratory system, allergies, asthma and immunological reactions (WHO, 2009, p.xii). The document goes on to state, “The presence of many biological agents in the indoor environment is due to dampness and inadequate ventilation” (2009, p. xii). With regards dampness heritage buildings behave differently when compared to modern-day construction types: solid wall constructions generally allow moisture to freely enter and exit the material and the building according to local environmental conditions – hence often regarded as a ‘breathable’ type of construction. By comparison ‘modern’ construction materials, such as concrete, typically do not allow moisture to move freely through the material. When modern materials are combined with heritage construction the ability of the traditional material to ‘breathe’ can be inhibited and moisture can become trapped. This moisture can subsequently result in mould forming and cause accelerated decay to building materials. Spores from mould reduce the quality of the indoor air, particularly if it is not adequately ventilated away.
Mould on the internal side of a wall
The World Health Organisation highlights how damp environments can exacerbate the poor quality of indoor environments and that the role of dust mites and fungi are of particular concern: ‘Dust mites and several fungi produce allergens known to be associated with allergies and asthma; many fungi also produce toxins and irritants with suspected effects on respiratory health’ (WHO, 2009, p.9). Many internal toxins can be invisible, but the appearance of mould within your building may indicate moisture is trapped and/or ventilation needs to be adjusted. It may also indicate a larger external problem where water is not moving away from the building adequately. The Society for the Protection of Ancient Buildings (SPAB) advises ‘Damp is the most common and damaging cause of deterioration affecting buildings of all types and rain penetration is usually the culprit.’ ( This, then, can include over-flowing gutters and damaged rainwater pipes. It is important to review your maintenance regime for your property and consider appropriate adjustments.
Image from Building Conservation Directory (
If you remain puzzled by the source of moisture or are looking for an objective opinion do seek professional advice from your local conservation architect or building surveyor. If your building is Listed or in a Conservation Area do review any possible repair work with a conservation architect to ensure works are appropriate. Living with heritage buildings, not despite them, can be a learning curve, but a great place to start is connecting with Heritage Revival via this blog. During 2019 blog posts are scheduled for release on Fridays every fortnight. Do follow us so you don’t miss an update. References Ece, N. 2018. ‘Building Biology: Criteria and Architectural Design’. Beltz Bad Langensalza GmbH, Germany. WHO, 2009. ‘WHO Guidelines for Indoor Air Quality 2009: Dampness and Mould’. Druckpartner Moser, Germany. ( Useful Links and Further Reading SPAB Preventative Maintenance Historic England Repair Work