Cork as a building material is currently undergoing a resurgence, in a time of global warming and ever increasing pressure on the environment the use of renewable and sustainable building materials should be high on the agenda. Evidence of the first cork floors was found in cathedrals in Spain and Portugal, often dating back to the 1870’s or even earlier. Prominent examples of cork floors include the US Library of Congress whose cork floor was installed in 1897 and is still in use today, the old Toronto Stock Exchange had cork floors installed to help ease the joints of traders who were on their feet all day and provided a quieter and more acoustic atmosphere than a hard tiled surface.
At that time, cork flooring installation was an exotic, expensive and laborious undertaking. Cork was imported at great expense as North America does not have cork oak forests. Great rolls or sheets of cork were glued in place, custom stained and then finished with hard wax or varnish. A complete installation could take weeks or even months depending on the stain and length of time it took the varnish to cure. The primary or first use of the harvested cork bark is for the extraction of cork stoppers to meet the demands of the world's wine and champagne industries. This amounts to over 13 billion cork stoppers annually. The remaining cork (called "blocker waste) is then ground up and processed for use in the production of agglomerated cork and cork and rubber compounds (a process developed in the late 19th century). These materials are used in a variety of applications from floatation devices, gaskets, bulletin boards, and most importantly in the fabrication of flooring materials.
In gathering cork bark it was the ancient Greeks who first discovered that stripping the bark from the tree produced a new, higher quality cork. Harvesting cork bark has not changed from these early times. The outer bark from the oak's trunk and major branches is still carefully stripped by hand by experienced cork strippers who use a specialized cork axe to slit the outer bark and peel it away from the tree. No mechanical stripping devices are allowed. The first stripping of bark (with the material known as virgin or male cork) occurs when the trees are a minimum of 15 to 20 years of age, with subsequent stripping done at 9 to 10 year intervals thereafter. Most countries can only (by law) strip bark when the tree is dormant in the winter months between December through March. The trees regenerate this outer layer 12 or 13 times during their 150 to 250 year lifetime. The harvested cork bark is then removed from the forests and left out in the open air for six months. This weathering process improves the cork's quality. The bark is then sorted by quality and size.
Cork’s key asset is of course its renewability however it does bring positive benefits to the home also:
- Cork is incredibly yielding, and for a natural material it is very forgiving creating a soft, cushioned surface. This is particularly useful in rooms which are used regularly such as kitchens and also children’s playroom’s where the occupants are protected against the occasional trip or fall.
- Cork is also a great sound insulator and therefore works well in apartment buildings to dampen the transfer of noise between properties; the same can be said for its natural insulator properties with respect to heat loss. Studies have shown that a cork floor can obtain an R Value of up to 1.125, the only floor covering achieving a higher R Value is a wool carpet.
- Unlike some other flooring materials cork can be refinished periodically. The surface can be sanded down to remove any imperfections and then re-sealed depending on requirements. In areas of high traffic this is important as it allows the user to simply refinish the floor rather than reinstate it entirely.
- Unlike carpet cork will repel dust and hair and is easier to clean than a carpet for example. These hypoallergenic properties will promote a higher level of indoor air quality and improve the environment within the home.
- Cork contains a biological product known as suberin which will naturally repel small vermin and other insects. Accordingly cork floors are far more resilient to the growth and/or colonisation of these organisms than a carpet would be for example.
- Cork is relatively easy to install and often comes in tiles that are adhesive backed and laid individually. Cutting around pipes, corners or radiators is simple and can be done carefully with a craft knife. In the event that a tile becomes damaged it can be taken up and replaced with minimal hassle, as would be the case with a ceramic or fitted hardwood floor.