What is it?
Most of us don’t notice it when we’re walking on it, but cork flooring has been naturally enriching interiors for over 100 years in notable buildings such as schools, hospitals, churches, museums, libraries and hotels. It’s warm honey-toned appearance, comfort underfoot and ability to soften acoustics often goes unnoticed by those of us who would not otherwise recognize it.
So what is cork? Cork is actually the outer bark of a tree, Quercus suber, which grows in the Mediterranean. Cork oak forests cover approximately 5.4 million acres amongst the seven primary cork producing countries; (30% Portugal, 21% in Algeria, 20% in Spain, 16% in Morocco, 5% in France and 4% each in Italy and Tunisia). Cork forests are carefully managed and treasured in particular by Portugal, which produces 50% of the worlds cork supply.
Cork bark is typically harvested every nine or ten years. After the slabs of cork bark are harvested they are cleaned, boiled and stripped of the rough outer surface. Bottle stopper “corks” are then punched from the best material in the slabs. The remaining scraps are then ground into small granules, mixed with a binder, molded into large blocks and baked in specialized ovens – making use of every scrap of cork bark.
Corks remarkable properties are derived from its cellular structure of hollow, polyhedral (14 sided) cells with extremely strong yet flexible cell walls that are waterproof and airtight. Joined together in a honeycomb like fashion, cork cells produce a very lowdensity, compressible insulating material. As a floor covering, cork is durable, provides acoustical and thermal insulation, cushions the foot, is resistant to moisture damage and decay and is easy to clean. In addition to all of these features cork is harvested from trees in a sustainable manner – making it very worthy of consideration for use in green building.
Natural cork flooring materials, which we are referring to, are quite different from the widely marketed cork-vinyl composite floor tile. Cork-vinyl products have a polyvinyl chloride (PVC) backing, a cork inner layer and a vinyl surface layer. Due to significant health and environmental concerns with PVC, natural cork flooring is preferred over vinyl.
Cork can be used as a flooring surface, an underlayment for flooring, on walls and ceilings, and is one of the main ingredients in natural linoleum. Cork has been formed into baseboards and moldings as well. In residential applications cork is successfully used in living rooms, kitchens, bathrooms and hallways.
The process of agglomerating the cork requires binders to hold the ground cork granules together. Urea formaldehyde binder was used in the past, (phased out during the 1980’s) and today, urea melamine, phenol formaldehyde and natural proteins are more commonly used. Once processed, these are relatively stable binders.
Corks impact on the environment is quite low due to the sustainable harvesting practices and almost zero waste from the manufacturing process. Producing nations regulate how frequently cork can be harvested in order to minimize damage to the trees. The trees survive the debarking process although they are more susceptible to injury until the protective bark is regenerated.
Most manufacturers offer cork tile in shades of light, medium, and dark, but there will always be shade variation from tile to tile.
Cork is generally available in rolls for underlayment or tiles for floor covering. Tiles are also available as floating floors and include both pre-finished and un-finished parquet tiles. Available from factories in many patterns and colors, tiles can also be stained for a unique custom color appearance.
Routine maintenance is a function of the finish applied.
Waxed finish – Clean with dry or damp mop, occasionally using liquid solvent wax. For a more serious cleaning on standard cork tile, use electric buffing with 00 steel wool discs then apply lamb’s wool pads.
Polyurethane finish – Clean with dry or damp mop. To refinish the polyurethane tiles use power floor machine with wool disc (00 grade) and apply polyurethane as directed on container labels.
Performance / Durability
Cork is highly abrasion resistant on it’s own and treating it with a protective finish further increases its durability. Cork has a tremendous amount of “memory” and recovers well from compression. Cork floors will last as long as most hardwood floors.
Just like any other flooring material, cork can be punctured by sharp objects and damaged by furniture feet. Protective pads under furniture are recommended.
If installing cork flooring in a bathroom take additional measures, such as caulking the perimeter of the room prior to installing baseboard, to avoid moisture penetration.