7 Causes of Damp and Mould

Damp, condensation, and mould are common problems in the UK with 1 in 5 dwellings suffering one or a combination of such issues. Airborne atmospheric moisture particles need somewhere to go and, if they cannot leave the property, will settle where they find suitable conditions, often resulting in the development of condensation leading to outbreaks of mould. However, by understanding how damp and mould develops in a property, tenants and landlords can begin to take action to prevent the issues from occurring.

Building faults

Damp and mould can be attributed to issues with the building itself typically, cracked render, missing mortar, damaged tiles and incorrectly installed windows and doors. Having any, or a combination of these issues allows water to enter the fabric of the building that can result in damp and mould developing if action is not taken quickly and effectively. Damp walls are more common in older properties built of solid brick, stone or concrete and some without damp proof courses. However, they consequently dry quicker. Newer homes are also prone to damp due to the installation of double glazing, draught excluders, central heating and the removal of open fireplaces whereby the implementation of these has in many ways, removed natural ventilation of the buildings and, if wet, can take longer to dry.

Poor ventilation

Adequate ventilation of a property requires fresh air to enter and moist internal air to escape. Therefore, if a property lacks adequate air flow, moisture can be generated on the coldest surfaces, quite often an external wall or as condensation on window panes. This excess moisture makes properties more prone to mould development. Ventilation issues are more apparent in the winter as occupants are more reluctant to open windows when it is colder outside. However, even creating a draught or an open window for a few minutes a day can allow some moisture laden air in the property to escape and, by ensuring the property is adequately ventilated, will help keep damp at bay.


Condensation is when vapour in the air changes into a liquid as it comes into contact with cold surfaces. Properties are more prone to suffer with condensation between October and April due to the cooler external temperatures not being introduced into the warmer property. However, it can appear any time during the year if the internal conditions support it. Condensation in a property can severely damage your home and could lead to health issues such as respiratory problems since 80-85% of mould problems are attributed to condensation, a man-made form of damp. When condensation does appear, tenants should wipe it down to reduce the moisture levels in the property and open the windows for a short period to remove the moist internal air.

Drying clothes

During the summer months, many people use the conditions outside to dry their clothing. However, when the weather starts to change, 80% of people turn to drying their clothes inside the property and certainly where outside security is an issue. Although maybe more environmentally friendly than using a tumble dryer, the drying of clothes on radiators and clothes horses increases the atmospheric moisture particles in the air. A single load of washing typically contains 2 litres of water which if dried internally, will become airborne leading to the likelihood of damp and mould developing in a property increasing by 30%.

Inadequate heating

Homes which are underheated can increase condensation levels and it is very common for people to switch on their heating periodically each day. However, these spikes in temperature can exacerbate a moisture issue by allowing the building to cool down resulting in the warm, moist air condensing on the colder surfaces which in turn can lead to the damp and mould. Having your heating on a low constant temperature throughout the day can help reduce the chances of damp and mould as it maintains a warmer structure and only operates when it is needed.


The kitchen is a common area in a property displaying damp and mould and, by understanding the causes of the issues, you can begin to prevent it from happening. From using the hob to boiling the kettle, kitchen areas can increase atmospheric moisture in the house on a regular basis and, as it is where we keep and produce our food, it is important to take steps to reduce the chances of damp and mould occurring. The best prevention methods include using an extractor fan or opening a window whilst cooking and, when finished, keep the door closed until the extractor or window has removed the moist air. These simple steps can help reduce the chances of damp and mould in this and other areas of the property.


Bathrooms often already have extractor fans fitted. However, unless ventilated correctly, the use of a bathroom can cause a build-up of moisture that, if left to move around the property, can lead to damp and mould developing in places other than the bathroom itself. Bathrooms without an extractor fan fitted will require leaving a window open to move warm moist air to the outside. And, to help this movement of air, the door to the bathroom requires an undercut at the base to help introduce make-up air flow into the room helping to push the moist air out. In some houses it is common to have bathrooms without a window or extractor fitted and, in these cases, tenants should leave the bathroom door slightly open after bathing but ensure there are open windows close by. The use of small portable dehumidifiers can assist the capture of moist air and will require emptying on a frequent basis.

About the Author

David Bly

David Bly

Managing Director

David has an Engineering and Management background having been involved with the property damage management industry sector for the last 20 years encompassing the management and dissemination of key reporting protocols. His field-based experience aligns to the creation and production of unique reporting systems that serve to uphold professionalism and transparency of data interpretation for the industries Cornerstone serve.

In addition, his experience aligns to the understanding of damp, condensation and mould related issues in properties combining all industry approved surveying techniques to deliver a bespoke service clients demand.

Cost Calculator
ROI Calculator

Enter data to create cost

Initial investment

1 day course

Annual investment

Costs per Survey / Property per year

Enter data to create cost

Costs per Survey / Property per year

Annual Savings Potential

Return on Investment (and disrepair)