We would like to take this opportunity to answer some of the questions that you may have about Multi-Foil Insulation. If you would like further information please do not hesitate to contact IPP, telephone 01621 776252.
Why should I use a BBA approved multi-foil?
British Agrément Certificates provide reassurance to users, designers, insurers and regulators. Agrément Certificates are recognised throughout the UK by architects, engineers and building control personnel. The BBA's impartial and unbiased information complement manufacturers own technical data on the performance of the product.
Which Multi-Foil Products currently have BBA certification?
There are 2 multi-foil products that carry BBA certification, these are Alumaflex and TLX.
How do non-BBA approved multi-foils perform?
It is difficult to compare non-BBA approved materials. Each product will make different claims about thermal performance. However, until these materials have undergone the stringent test criteria required by the BBA it is difficult to draw any conclusions about performance, and therefore impossible to compare them with products that have undergone testing by the BBA. These tests include ageing, thermal tests and mechanical tests.
Do all insulation materials have the same thermal performance for walls and roofs?
No, values vary and reference should always be made to the relevant BBA certificate. The following table provides a comparison of BBA certified products in walls and roofs:
|Brand||R Value (wall)||R Value (roof)||R Value Core||Emissivity||BBA Number|
Ref : Table 1 (The lower the emissivity the greater the overall thermal performance) The overall performance for the product will vary and will depend upon the airspaces on both side of the product and vertical or sloping application.
Eg. of a Total R Value. Alumaflex in a wall with a 25mm airspace on both sides will have a total R – Value of 2.22 m2 K/W 0.9 + (2 x 0.66)
Which Multi-Foils do not carry BBA Certification?
There are several brands that include Tri-Iso Super 10, Superquilt and SF19.
What U-Values will I achieve with a BBA approved product?
U-Values achieved will vary – the higher the R-Value for the multi-foil the lower the U-Value will be achieved. To ensure that walls and roofs using multi-foils meet Building Regulations it is always best to refer to the manufacturers British Agrément Certificate. This guarantees thermal performance and provides technical information regarding Building Regulations and Product Performance.
Can a multi-foil be used on its own?
Multi-foils can be used on their own, but they would need additional insulation within the roof and wall construction in order to meet the current U-Values required under the latest Building Regulations Part L 2010.
Can I use two layers of multi-foil?
Yes, but a 25mm airspace is required between the two layers.
Will all Building Control Bodies allow multi-foils?
As long as the product carries BBA certification then the builder can be confident that the multi-foil will be accepted by the local building control. Most Building Control Bodies stipulate that Multi-Foils should be tested according to BR443.
What thickness of additional insulation is required to achieve the necessary U-Value?
Target U-Values vary depending upon the nature of the detail and project. It is therefore always best to check with either the architect, multi-foil manufacturer or Building Inspector. Sample calculations for walls and roofs are now available in the latest copies of the manufacturers agrément certificate.