Interstitial condensation

Interstitial condensation is often overlooked and yet is capable of causing significant damage over time. This phenomenon occurs when warm, moist air infiltrates a building's structure and condenses within its walls. This can happen particularly during the winter when parts of the solid wall drop in temperature to the dew point. Solid walled buildings, commonly constructed from materials like brick, or stone, are particularly vulnerable to interstitial condensation. Understanding its effects, especially in terms of thermal dynamics and dampness, is crucial.

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Thermal Effects:

The presence of interstitial condensation can disrupt a building's thermal performance in several ways. Firstly, when warm air laden with moisture permeates the building envelope and condenses within the walls, it creates a thermal bridge. This bridge facilitates heat transfer between the interior and exterior of the building, leading to increased energy consumption as heating and cooling systems work harder to maintain desired temperatures.

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Dampness:

Additionally, interstitial condensation can result in visible manifestations of dampness, such as water stains on interior walls and ceilings. These aesthetic concerns not only detract from the visual appeal of the building but also indicate underlying structural issues that require immediate attention.

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Mitigation Strategies:

Solid walled buildings rely on the ability of lime based materials to allow the passage of both vapour and condensed moisture. This means moisture within the building can be effectively transported from the inside to the outside. It’s important to note that the moisture will move from moist areas to dry areas and so if it’s particularly humid outside moisture can occasionally be drawn in. Ventilation is of course the other main strategy for managing dampness in solid walled buildings. Background ventilation from chimneys and draughty doors and windows, open windows, and powered ventilation in bathrooms, roof spaces and cellars.