20 Jan Thermal Bridging Causes Condensation
The term thermal bridge is also known as cold bridging. It occurs when there is a direct connection between the interior and exterior of a building. This can be either through elements which have a greater thermal conductivity or gaps in insulation.
These elements such as rafters or purlins can be described as weak points resulting in heat transfer and therefore, the internal temperature of its surface will differ from adjacent insulated surfaces. During winter months when heated moist air is circulating within the building it may come into contact with the cold surface of the thermal bridge element and significant condensation may occur.
In some cases the condensation can drip onto factory floors or electrical installations causing significant health and safety issues.
Older buildings are more likely to suffer from cold bridges due to the poor level of insulation. Many older buildings were constructed with single skin metal or cement asbestos roofs with single skin glazing. Legislation has ensured that modern buildings are constructed to levels where thermal bridging is less likely to be a problem
Thermal bridges can be identified using thermal imaging if they are not visible with the naked eye. Purlins are considered as ‘repeating elements’ as there are normally many of them at regular intervals.
Solving the Problem of Cold Bridging
As previously outlined cold bridging can cause condensation and whilst adequate ventilation or de-humidifiers may help, the best solution is good thermal insulation.
The most effective way of either an old or new building is by utilising spray foam insulation, the reasons for this are:
- Speed of application.
- Air sealing – it is a completely seamless system which seals any gaps and prevents the ingress of cold air into the building envelope.
- Significant reduction of heat loss – U values can be reduced from 7W/m2/oC (single skin metal) to approximately 0.5W/m2/0C, which equates to over 90% saving.
- Eradication of surface condensation.
- Minimal disruption to operations within the building.
At Green Insulation UK we can advise on the best way to tackle problems with thermal bridging, heat loss and condensation. Please get in touch.