Why Cork?

Cork stands as a testament to nature's ingenuity, offering a 100% sustainable, versatile, and resilient material prized for its myriad applications in architecture, design, spaceships and beyond. No wonder why Humanity has been harvesting the bark of cork oaks for thousands of years.

Cork has always been a part of my life in Portugal. Cork trees are everywhere in the country, and cork is used in many aspects of life there, from boats to the space industry, sports, sound engineering, internal finishes, insulation, saunas, stamps, furniture, cladding, jewellery, footwear, clothing, insulation and, of course, wine stoppers. The Portuguese industry of cork has been organised for over 300 years and the country is the largest producer of cork in the world.

What is cork?

“One day, I still hope to be able to make a house completely out of cork. It will generate a fusion of new material, space, function and experience. Cork is above all a timeless material that links the past, present and future thanks to its sustainability. It is what connects nature, architecture and people. Cork offers me this extremely fertile possibility.” - Sou Fujimoto

Humans have understood the material benefits of cork for over 5000 years.?It's a natural material harvested from the bark of cork oak trees (Quercus Suber) and thrives primarily in the western Mediterranean region, encompassing countries such as Portugal, Spain, France, Algeria, Morocco, Italy, and Tunisia.

Over the course of history, efforts have been made to cultivate the cork oak tree in various continents, including America and Asia. Despite some regions boasting favourable climates for its growth, these attempts have not yielded complete success. Consequently, it has become evident that the cork oak tree prefers to thrive exclusively within the Mediterranean region.

Cork could be found, for example, in ancient Egyptian sandals and nautical elements and the antient Romans already used it in rooftops and ceilings for its thermal insulation properties, as well as in pitchers, as a sealant. In the Middle Ages, cork was widely used in the Portuguese ships and, since the inception of space exploration, Portuguese cork has served as the insulation material chosen by both NASA and the European Space Agency (ESA) for a variety of programs and missions, including space shuttles and rockets. Notably, it was utilized in missions like Apollo XI, which marked the historic moment of the first human landing on the moon.

Within every cubic centimetre of cork, over 40 million cells are packed, containing microscopic amounts of air composed of nitrogen and oxygen.

Approximately 45% of cork's chemical makeup consists of suberin, a component renowned for imparting significant elasticity to the material. Complementing this are other constituents: lignin (27%), known for its insulation properties; polysaccharides (12%), contributing to cork's distinctive texture; tannins (6%), responsible for its coloration; and ceroids (5%), ensuring impermeability. This distinctive cellular structure imbues cork with exceptional properties:

Impermeability: the inclusion of suberin and ceroids within cork cell walls renders it nearly impermeable to both liquids and gases. This inherent resistance to moisture further allows cork to undergo aging without deterioration.

Thermal and acoustic insulation: cork exhibits low conductivity to heat, noise, and vibration due to the encapsulation of its gaseous components within small, impermeable compartments. These compartments are effectively isolated from each other by a water-resistant substance, significantly reducing conductivity levels. As a result, cork surpasses many other materials in its ability to control noise and temperature variations, making it an excellent resource for insulation purposes.

Fire and heat-resistant properties: Cork exhibits fire-retardant characteristics, burning without producing flames and emitting non-toxic gases during combustion. This unique attribute underscores the significance of "montados" in mitigating the spread of forest fires within their ecosystems and suits the cork application in architecture.

Friction resistance: Cork boasts resistance to abrasion and a high friction coefficient, thanks to its cellular honeycomb structure. This unique construction grants cork exceptional durability against impacts with other materials, surpassing that of any other solid surface.

Elasticity, compressibility, and resilience: Cork possesses remarkable elasticity, allowing it to be compressed up to half of its volume without sacrificing flexibility. Upon decompression, cork effortlessly regains its original shape and thickness. Moreover, when compressed on one side, cork does not expand on the opposite side, making it exceptionally adaptable to environments with fluctuations in temperature and pressure. Cork's unique structure allows it to be compressed and then instantly revert to 85% of its original size to form an airtight seal. No man-made material has this capability.

Hypoallergenic properties: Cork's inability to absorb dust renders it an excellent ally in allergy prevention, significantly reducing risks for individuals with asthma. Furthermore, its immutable composition contributes to its reputation as a highly dependable material. This is one of the reasons why the use of cork in medical facilities, schools and saunas has been increasing.

Comfortable and tactilely pleasing: Despite its naturally irregular texture, cork possesses a soft and pliable quality, providing a pleasant tactile experience. It's a natural material that takes us back to our natural environment.

Lightweight: With approximately 60% of its composition being air, cork weighs a mere 0.16 grams per cubic centimetre.

Is the production of cork sustainable?

In Portugal, stringent regulations govern the cork industry to guarantee sustainable production practices, and that workers receive fair wages. By law, cork oak trees must reach a minimum age of 25 before any harvesting is permitted, and even then, harvesting can only occur every 9 to 12 years. Each harvest will produce an average of 40-60 kg of cork per cork oak tree.

The meticulous and highly sustainable process of harvesting cork is conducted with specialized techniques, ensures sustainability while preserving the health of the tree. Remarkably, stripping the outer bark does not harm the cork oak tree; instead, it stimulates bark regeneration, potentially extending the tree's lifespan, which can span up to 250+ years. Harvested cork trees absorb 3 to 5 times more CO2 than non-harvested trees. Cork oak trees in Portugal alone help offset 10 million tons of carbon every year.

Notably, cork oak trees possess a unique resilience, enabling the stripping of bark without compromising their overall health—an unparalleled characteristic among trees worldwide.

In the factory, cork undergoes shredding and compression at elevated temperatures, prompting expansion and the melting of sap to create a natural adhesive that binds the material. After cooling, the cork is cut to precise measurements, ready for use as cladding or other purposes. Every part of the harvested bark is utilized in this process and, remarkably, no additional ingredients are introduced into the process! The transportation of cork to construction sites is essential but the associated carbon emissions are much lower when compared to materials like wood or bamboo, due its low weight.

Cork is not an endangered natural resource, and the cork forests ecosystem is extremely fire-resistant, making them extremely important in a country where forest fires are recurrent.

"Cork oak forests support one of the highest levels of biodiversity among forest habitats, as well as the highest diversity of plants found anywhere in the world." – World Wildlife Fund

But is cork recyclable?

YES. Cork is 100% recyclable and demands minimal energy consumption during its production process. A notable portion of the energy needed for manufacturing is met through the utilization of biomass.

Cork in Architecture

"It is a natural material, with strong added value in terms of touch and smell, and great versatility, which allows it to be easily carved, cut, shaped and formed." - Herzog & de Meuron

The versatility of cork as a material has led to its increasing adoption in both interior and exterior applications within buildings. Internally, cork serves to regulate humidity, absorb odours, and provide pleasant sound reverberation, particularly suited for environments seeking an organic, inviting ambiance. As external cladding, its impermeability shields buildings from the elements, offering significant and REAL carbon-negative benefits.

From an aesthetic standpoint, cork offers a distinctive and natural appeal that adds warmth and character to architectural designs. Its unique texture, ranging from smooth to rugged, creates visual interest and depth, enhancing the fa?ade's visual appeal. The natural variations in color and grain patterns of cork further enrich its aesthetic appeal, allowing architects to create dynamic and visually captivating exteriors:

Warmth and Texture:?Cork brings a unique warmth and textural dimension to any space. Its natural honey-brown color adds a touch of sophistication and elegance, while the subtle grain patterns create visual interest.

Modern Appeal:?The natural and sustainable qualities of cork resonate with contemporary design trends, offering a unique aesthetic that complements modern architecture.

Customization Potential:?Cork can be dyed, stained, or treated with various finishes to achieve different visual effects. It can also be cut, carved, bended as per our imagination. This allows architects to tailor the material to their specific design vision and create truly unique facades.

The examples below, mostly built with Portuguese cork, illustrate the versatility of this amazing material both in internal and external areas: the different shapes, the volume and scale play, the golden relaxing light in the interiors, the cladding colour change depending on age, location and weather and the interface with so many materials: