Expanded Cork

Expanded cork is a 100% natural product commonly used for insulation in the form of Insulation Cork Board (ICB). We supply expanded cork boards in a range of thicknesses from 10mm up to 300mm and also expanded cork granules in a range of different granule sizes. Expanded cork is made from cork that is too resinous to be used for wine corks and is surely the most environmentally friendly insulation material on the planet, given that it is effectively carbon negative as trees are not cut down to produce it (only the bark is removed, which grows back every nine years).

Expanded Cork

The abundance of naturally occurring resins that are to be found in the cork bark made to use expanded cork are used to bind granules under pressure without using any additional adhesives. The cork is stripped from the tree every nine years (this process does no harm to the tree) and is granulated and placed in an autoclave. Then super-heated steam is added which releases the resins held within the cork granules and this resin serves as the adhesive to bind the granules together. Blocks that are sized 100x50x30cm are produced, which are cut down to make boards of the thickness required. You can read more about how expanded cork is made here.

Expanded Cork

Here are shown expanded cork granules, which can be added to cement to make it more lightweight and with better insulating properties as well as being an insulating filler for cavities.

The technical characteristics of expanded cork are:

  • Thermal conductivity coefficient – 0.040 W/m.K
  • Density – 105-125 Kg/m3 (7.0 – 7.5 pounds per cubic foot)
  • Tension to stress – 1.4-2.0 KGf/cm2
  • Functional temperature range – -180ºc to +140ºc
  • Fire class – Euroclass E
  • R value – 3.6 per inch
  • Compressive strength – 15 psi
  • Moisture permeability – 2.2 perms at 40mm

The are three different densities of expanded cork, with the standard density being used generally for wall, roof and floor insulation. The high density expanded cork is used for internal and external cladding and the very high density expanded cork for more decorative purposes as it is suitable for CNC milling.

You can see our expanded cork board prices here and there is information on non-expanded coarse granule cork insulation boards here. We also have available prices for expanded cork granules, for different size expanded cork granules.

You can download expanded cork technical data here and find out about the installation of expanded cork here.

Here is a video of a visit to our expanded cork factory and cork forest that we organised for a client of ours, to show how cork is harvested and then transformed into expanded cork

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