Thermal Calculator - Terms of Use

Please read this information before using our Thermal Calculation tool

This U-value calculation is provided to customers free of charge and is based on information you have entered. The calculation is for indicative U-value purposes only and does not imply any other performance criteria, e.g. fire, acoustic etc., which must be dealt with via separate communication and/or by reference to our current specifications and recommendations in the White Book. No duty of care is owed to the recipient or any other third party and British Gypsum cannot accept liability in respect of the information shown. The specification should therefore be approved by the project design and management authority before use to ensure that it meets with their specific project requirements. This calculation must be read in conjunction with current literature at or British Gypsum/Isover products must be installed in accordance with current literature and relevant standards. The properties and suitability of any non British Gypsum/Isover products must be verified with the relevant manufacturer prior to installation. Any bonded wall lining system identified assumes background suitability - where any uncertainty exists an alternative mechanically fixed lining system should be considered. All wall lining solutions to masonry backgrounds assume that the background is dry and completely weather tight.

Following recent research within the construction industry using Hygrothermal properties of buildings components within modelling software, and in compliance with BS EN 5250 (August 2016), we now recommend the guidance of a specialist consultant in the field of hygrothermal performance be obtained prior to commencing the installation of internal insulation to solid masonry walls in order to determine the effects of condensation and moisture within the building fabric.

This area of expertise is documented within BS5250 ‘Code of practice for the control of condensation in buildings & BS EN 15026 Hygrothermal performance of building components and building elements – Assessment of moisture transfer by numerical simulation.

If the type of construction you have is not included within this database, please send your enquiry, describing the precise make-up, u-value requirement, site address and contact details, to