Isover Metac

Metac is a robust ‘slab on a roll’ glass mineral wool insulation, whichcan be considered for use between rafters in pitched roof applications.It offers a 2-in-1 solution for its thermal performance and sound reductionproperties. The strong, resilient and flexible rolls are available in a rangeof thicknesses to suit common rafter depths. 

Metac can also be considered for thermal insulation between the joists inflat roofing applications.

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Product Features

  • Glass mineral wool roll (1.2m wide) supplied in 50-200mm thicknesses
  • Manufactured from a minimum of 50% recycled glass

Fire Classification

Euroclass A1 Reaction to Fire classification according to EN 13501-1.

Product Specification

Thickness (mm) Length (m) Width (m) λD Declared thermal conductivity (W/m.K) RD Declared thermal resistance (m².K/W)
50 9.30 1.20 0.034 1.45
125 4.80 1.20 0.034 3.65
150 4.10 1.20 0.034 4.40
175 3.50 1.20 0.034 5.10
200 3.20 1.20 0.034 5.85

Product Benefits


  • Thermal Performance - Thermal conductivity of 0.034 W/m.K. Helps to reduce heat loss within the building envelope and decrease energy costs.
  • Acoustic Performance - When included within particular pitched roof rafter systems, Metac can help achieve a weighted sound reduction of up to 49 dB (RW), delivering excellent external noise reduction for those living or working within the building.*
  • Sustainability - Manufactured from a minimum of 50% recycled glass. For further details visit
  • Easy to Install - Metac friction-fits between rafters without slumping, or the need for any additional fixing. The roll width allows cutting to different rafter centres, providing maximum flexibility and efficiency on site, with minimal waste (off-cuts can be reused).
  • Fire Classification - Achieves a Euroclass A1 Reaction to Fire classification, according to EN 13501-1      

        *Tested by the University of Salford to BS EN ISO 10140-2:2010

Key Considerations

When using Isover Metac, you need to satisfy yourself that use of the product meets all relevant national Building Regulations and guidance as well as local, national and other applicable standards relevant for your construction or application, including requirements in relation to fire and applicable height restrictions.

Please refer to the following product documents: