OCT 16

Cork is a very versatile material with a great green pedigree. It is considered a rapidly renewable material because the bark of the cork oak can be harvested without killing the tree, allowing repeated cycles of production over the 200+ year lifespan of the tree. While cork has long been an attractive choice for flooring, it is now being used to provide building insulation boards, as well.

Like cork flooring, the cork insulation is also made from granules of cork that are left over after wine corks have been punched out of the bark. Cork granules are treated under heat and pressure to release a natural binder and produce billets of expanded cork which are then cut to size. The expanded cork has an R-value of 3.6 per inch. This isn't as good as the highest performance materials, but is comparable to fiberglass batts, cotton (blue jean insulation), and cellulose insulation.

Expanded cork insulation at present is a comparatively expensive material for insulation. The cost comparison from Building Green (who have an extensive write-up of the material) indicates that cork might be as much as 5 times the cost of a similar amount of polyisocyanurate insulation board, and more than twice as expensive as extruded polystyrene. But the cork does not rely on petrochemicals for its manufacture, and offers an all-natural insulation product that will definitely appeal to some builders and building owners.

In addition to its energy performance, the cork insulation is also highly flame resistant, helps with sound absorbtion, and does not offgas any significant VOCs. From a LEED perspective, it is a very useful material, qualifying as a rapidly renewable material in addition to being manufactured from the waste byproduct of the manufacture of another product (wine corks). Many cork forests are already FSC certified. And, from the perspective of a materials red list, it is 100% natural.

via: Jetson Green

Comments (5)

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Like Cork
written by HotTubWorks, October 17, 2012

We tested cork as possible hot tub cover component. The insulation factor seemed to do well but the weight and cost killed the project quickly.

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Cork as insulator
written by Tem, October 17, 2012

Cork was used for the refrigeration facility at a local vegetable packing company (Birds Eye) back around 1950. Its insulating properties were well known back then.

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Greenbuild
written by Francisco Simoes, November 07, 2012

Hi,

Expanded Insulation Cork Board will be at Greenbuild in San Francisco at booth 221S.
If not visiting feel free to contact me for a business visit.

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Good
written by Jake Myers, November 12, 2012

Good article. I am getting a st cloud insulation company to come to my house and get new insualtion in our home. I like knowing there are different kinds of insulation to talk about.

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Cork, a protected species
written by Green Business Watch, December 03, 2012

What a versatile material it is and a shame that it is an industry which has suffered recently from changing weather patterns causing a drop in quality. This has particularly been true in Portugal for example with the wine industry moving to plastic 'corks' and screw caps. The renewable cycle of production is so important that in Portugal it is illegal to cut down a cork tree.

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