A sustainable and stylish solution for commercial interiors
By Paulo Rocha Product & R&D Manager Granorte
ONCE popular in kitchens and bathrooms in homes across the country, cork has become a serious proposition in commercial interiors. Thanks to the material’s sustainable qualities, unusual natural aesthetic and manufacturing innovation, cork is proving relevant today more than ever before.
Unlike wood, which requires felling, cork forests are largely unaffected by the sourcing of material, as it is the bark of the tree which is used to create product.
After about 25 years of growth from a sapling, the bark can be harvested for the first time and then again in another nine years or so, or once it has grown back sufficiently.
This cycle can be repeated throughout the tree’s life, which can be up to 300 years. This makes cork a truly natural product and perhaps one of the most sustainable materials currently available in flooring.
Nearly half the world’s production of cork comes from Portugal, where its farming is strictly controlled. No trees are ever cut down or removed without government intervention and such is the country’s history with the material that the first regulations protecting cork trees date back to the 13th century.
Primarily making wine-stoppers, the cork industry has worked hard to reuse its waste in a range of by-products. Not only flooring, but also wall coverings, fabrics and even furniture and sanitary ware; cork really is a wonder material.
The process used to produce these cork products uses the same raw-material used to make wine-stoppers, meaning it’s easy to take the waste without any high-impact conversion or extraction.
Recycling this waste is done through two main methods – granulation and agglomeration – both of which produce different end-products.
Granulation uses all the waste from the cork-stopper production process where the offcuts are milled into cork grains of several dimensions, which are then sorted by size and weight. The granulated cork obtained is then used in several industries, from construction to high-tech or agriculture. These grains are also the material for agglomerated cork.
To make agglomerated cork, a binder is mixed with the cork grains and then the mixture is compressed into blocks under high-pressure as the binder cures. This process may be accelerated with a high-frequency catalyst, producing heat from inside out.
The type of cork grain, the type of binder and the amount of pressure determines the agglomerate; soft and low-density for insulating materials, hard and high-density for flooring, or bigger pieces of cork mixed with grains for decorative blocks.
For flooring, the density of agglomerated cork should be higher than 500kg/m3 – around five times more than the natural state. The binder is a special polyurethane pre-polymer that’s used in low quantity (about 5-7%) and which maintains the natural characteristics of cork. The binder has no toxicology, formaldehyde or VOC content, making the end product graded as high as food packaging.
There are two main types of cork flooring: in tiles, solid or veneered, and as a floating floor (a construction similar to engineered wood or laminate). The most traditional, and the floor that dominated kitchens in the mid to late 1900s, solid cork tiles relies on pressing granulated cork into a block that is then sliced into sheets before being cut into tiles.
Veneered cork tiles are made by gluing one type of decorative cork veneer (about 1mm thick) on top of another sheet of solid agglomerated cork and are glued directly to the floor.
Cork floating floors are produced in multilayer planks, consisting of a compact high-density fibreboard (HDF) layer, a bonded surface layer of cork floorcovering and a back layer of soft agglomerated cork for additional performance benefits. The core material (HDF) is tongued and grooved with a Uniclic profile to allow the panels to be assembled together mechanically, without the use of glue.
Today, many of the cork floors suitable for commercial interiors are of floating floor type. This has numerous advantages in terms of installation, function and even performance over ‘traditional’ glue-down cork tiles.
Granorte has specialised in developing cork floating floors that offer exceptional performance in a huge array of looks, just by altering the top veneer layer. The rest of the floor’s composition remains constant, allowing floors to be engineered with commercial performance levels, while delivering an incredibly diverse array of surface looks.
By using different types of cork mixtures within the top veneer level, Granorte is able to provide everything from ‘classic’ cork looks, right through to hugely expressive linear and coloured effects; the possibilities are endless.
In terms of decoration, it’s immensely versatile and while delivering a sought-after natural aesthetic that differs from traditional wood, it’s also possible to digitally print directly onto the surface of the cork veneer layer, leading to interesting results.
Particularly effective with tile effects, the digital print leaves a slight translucency that reveals the natural cork beneath. Most striking in its natural form, the richness of cork looks means it’s easy to find a look suitable for any project.
Yet it’s not just the sustainable and aesthetic qualities of cork that make it suitable for use in commercial interiors, as the material is equipped with a host of benefits that make it a great surface not only for floors, but also walls, ceilings, countertops, units and more.
With an open cellular ‘honeycomb’ construction, cork is an excellent insulator and this structure, along with the bark’s natural chemical composition, also makes it exceptionally strong. The cellular membranes are very flexible, making the cork compressible and elastic and this helps it to stand up well to the repeated impact of footfall.
Under pressure, gases within the cellular structure compress and when the pressure is released, these gases immediately return to original volume, meaning cork provides lasting underfoot comfort.
This same structure also makes cork one of nature’s best insulators, acoustically and thermally. For this very reason, 1.5mm thick agglomerated cork is used as the bottom layer on cork floating floors to provide additional acoustic performance.
Cork is used in some specialist acoustic underlays, so even a thin-layer built into the floor itself can do much to combat noise. Granorte cork floating floors can reduce impact noise by 19dB; far more than wood, laminate or vinyl floating floors.
Cork’s honeycomb structure also makes it remarkably resistant to wear and impact, meaning cork floating floors can be rated Class 32 Commercial.
Granorte cork floating floors are also protected with specially developed Weartop or Hotcoating high-performance coatings for easier maintenance and protection from stains and scuffs. Naturally fire retardant and with no noxious gases released, they also perform exceptionally in flammability tests.
Together, these properties make cork an appropriate material for use in flooring; sustainable, comfortable, quiet, warm, durable and easy to look after. Cork floating floors offer performance that other flooring materials and constructions struggle to match.
Recently too, the reasons for choosing cork have become even more compelling with the introduction of a floor completely free of PVC.
Granorte’s Kenko range of floating floors provide a completely PVC-free alternative to rigid-core vinyl flooring. By placing a decorative layer on top of an agglomerated cork cushion layer, HDF core and agglomerated cork base, Kenko brings the look of the best vinyl floors, but uses a PVC-free super-thin 0.25mm wear layer developed in Japan to completely eliminate PVC from the construction. Featuring Microban antibacterial protection and with Uniclic, Kenko brings the look of wood, with the ease of vinyl and the performance, comfort and sustainability of cork.
For commercial interiors that value sustainable materials, cork ranks among the very best flooring materials available today, but its low-impact is only half the story. With great performance, comfort, acoustic absorption and thermal insulation, as well as peerless aesthetics; cork is a serious proposition in a wide range of commercial interiors.