Spray Foam Insulation

Checking the Condensation Calculation

Condensation risk analysis

The condensation risk analysis calculation procedure carried out by WALLTITE considers both interstitial and surface condensation.

Interstitial condensation occurs when relatively warm moisture-laden air diffuses into a vapour-permeable insulation material.   If it is relatively warm on one side and below the dew point temperature on the other this can result in the moisture-laden air reaching dew point within the material and depositing liquid water.

More common is the condensation that occurs when upgrading the thermal insulation in the fabric of older buildings.  In this instance, the WALLTITE risk assessment will consider the materials used in the structure together with the building type, anticipated use and the local climatic conditions in order to build up a comprehensive picture of the project and provide the information the designer needs to choose the appropriate solution.  The output gives detailed recommendations on the type of materials, their depth and their application.

Thorough design data and calculations are also required in new build design and the WALLTITE risk assessment will consider similar issues to provide an insulation guide for the specifier.

The calculation method used in this risk assessment is set out in BS 5250 2002 (Code of Practice for the control of condensation) and uses the method of analysis quoted in BS EN ISO 1388.  A similar principle lies behind the standard U Value calculator (also provided by WALLTITE’s technical team), but building physics is a complex area more open to variations and specific site conditions that require interpretation before an accurate result can be produced.  Our experience of working with spray foam insulation over many decades and in various climates allows us to give very accurate technical information on performance.

WALLTITE is happy to provide a risk assessment and can do so upon the provision of cross-section diagrams of the structure, together with information on the building type, its use and its location.

To find out more and to access this free service, email john.bullen@basf.com


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