Advice provided by: Sarah Gudeman, LEED AP, EIT, Morrissey Engineering, Inc.

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Cork flooring combines the appeal of a natural material with a comfortable, cushioned surface that is naturally water-resistant and doesn't facilitate growth of mold or mildew. Additionally, characteristics like durability, insulation and acoustical benefits make cork all the more appealing. Cork is also buoyant, elastic and fire resistant.

But besides wine bottle stoppers (accounting for approximately 60% of all cork production by revenue), where does cork come from?

Origins of Cork Flooring

The Cork Oak tree (Quercus suber) is native to southwest Europe and northwest Africa (though the largest concentration of cork flooring plantations are in Spain and Portugal).

The bark is harvested (i.e. peeled off) after the tree reaches a maturity of no more than 30 years. The harvesting does not harm or destroy the tree. Waiting 30 years before the first harvest might seem like a long time (especially since the first harvest isn't the highest quality) but Cork Oak trees have a typical lifespan of 150-250 years, so that's just a drop in the bucket.

The tree's longevity means that the bark of a single Cork Oak may be harvested anywhere from 10 to 18 times in it's life. The bark grows back and another harvest takes place on a cycle. Harvesting must be done carefully, following specific requirements regarding location and depth of cuts, since disruption of the inner core can kill the tree.

Cork as Rapidly Renewable Material

With an average harvest cycle of 9 years, cork qualifies as a rapidly renewable material. Compare this to the nearly 30 years required for spruce/pine/fir forests.

The intent of utilizing rapidly renewable materials in construction is that it helps to reduce the use and depletion of finite raw materials and those with long growth cycles. Rapidly renewable materials are typically defined as those that are planted and harvested in a cycle of ten years or less. Both environmental and economic benefits can be realized by the project team and owner through use of such materials.

Cork Flooring and LEED

According to the LEED 2009 BD+C Reference Guide, the goals for use of rapidly renewable materials should be established early in the design phase. Products and vendors should be identified in the project specifications and construction documents, and acceptable alternates should be determined.

When it comes to flooring, for projects pursuing LEED certification, cork floor finishes must meet the requirements of South Coast Air Quality Management District (SCAQMD) Rule 113, Architectural Coatings, if the project is pursuing IEQc4.3 (Low-Emitting Materials).

Cost of Cork Flooring and Installation

Cork flooring can be installed as either adhered tiles or as a floating floor. For tiles, an approximate size would be 36”x12” with a thickness of 7/16”. Various finishes are available from most manufacturers, who bundle the tiles into 21 square feet per carton (each carton weighs only 32 lbs and costs about $130, making cork cost approximately $3-4/sq ft.)

Many products come with a residential lifetime warranty and a commercial warranty of ten years. Installation requires that the product be laid out in the room to acclimate for about 48 hours before they are to be fixed. If used with heated floors, the temperature should not exceed 82°F and cork flooring isn't recommended for spaces with high humidity due to expansion.

Maintenance for cork flooring is pretty painless: sweep, vacuum or clean with a damp mop regularly, don't let water or other liquids stand on the floor and protect from general furniture wear when possible. One other item worth mentioning is that cork will weather due to exposure from UV light. While this is 'normal', consumers should be aware that sunlight will cause color variations over time, so items like rugs and large furniture should be moved periodically.

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