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Interstitial moisture

The interstitial moisture (condensation within the building structure) stream looked at moisture management in roof spaces - both residential and commercial.

This part of the WAVE programme tried to understand the complex airflow patterns that can occur in roof spaces and how these can be controlled in such a way that they manage moisture effectively.

Projects in the interstitial moisture stream

Roof experiments

We built an outdoor test facility to continuously monitor full-scale commercial and residential roof specimens to investigate the complex issues related to the formation and removal of interstitial moisture in roof spaces.

A main focus was the role of ventilation on the dynamics of interstitial moisture in roof spaces:

  • How much roof ventilation is required to prevent moisture problems?
  • If extra ventilation is required, what are the best ways to provide it?

This experimental work was supplemented by field ventilation surveys in residential and commercial environments. These gave a snapshot of the level of ventilation currently present and provided essential information for the test facility and the subsequent modelling effort.

Numerical modelling

In roof spaces - air cavities and the building elements surrounding them - heat transfer, air movements and moisture transport are strongly linked and affect the formation and the removal of condensation.

We aimed to build a comprehensive numerical model of the transport of heat, air and mass in roof spaces to interpret the data collected in the test building and to generalise this to a variety of roof designs and climatic zones. Such a model would allow us to study the performance of different roof designs and ventilation strategies and would be a fundamental tool for generating Verification Methods and design guidelines.

More information

Explore the range of web and print resources related to this stream of the WAVE programme.