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Thermal & sound insulation expanded cork boards

Do you find yourself shivering at home in winter? And in summer, does your flat feel like an oven? That’s a clear sign your insulation isn’t doing its job. You keep having to turn up the heating or switch on the air conditioning. The result? High bills and no real comfort in your own home. On top of that, there’s the street noise that makes it impossible to relax. The place that was meant to be your haven starts to feel exhausting. But don’t worry – there’s an easy fix. Expanded cork is a clever way to stay comfortable all year round.

Got questions? You’ll find the answers right here!

WHAT IS EXPANDED CORK?

It’s a completely natural insulation material with a dark brown colour, available in boards or granules. Expanded cork offers even better insulating properties than standard cork boards – it retains heat more effectively, protects against high temperatures, and absorbs sound exceptionally well.

HOW IS EXPANDED CORK DIFFERENT FROM STANDARD CORK?

The main differences lie in the colour, properties, and production method. Most cork products you’re familiar with – such as coasters, noticeboards, or flooring – are made from what’s known as agglomerated cork. This material is produced by bonding small granules of cork together with an adhesive.

Expanded cork, on the other hand, is made differently – it’s a 100% natural material in which the granules bond on their own thanks to a natural resin called suberin, released during heating. As a result, it has a dark colour and a distinctive, porous texture.

Standard (agglomerated) cork is lighter and smoother, which is why it’s commonly used for decorative or practical products such as flooring, wall coverings, or noticeboards. Expanded cork, however, is ideal for thermal and acoustic insulation, especially in eco-friendly and passive buildings.

HOW IS EXPANDED CORK FOR WALLS MADE?

The production of expanded cork is a bit like making popcorn – except instead of corn kernels, you use granules from the bark of the cork oak tree. Inside a special mould and under high temperature, the granules begin to expand, darken, and stick together using their own natural resin, called suberin.

No glues or additives are needed – the process happens entirely naturally. The result is a dark cork with a porous texture and excellent insulating properties.

WHAT IS EXPANDED CORK USED FOR?

Expanded cork is used wherever enhanced thermal, acoustic, or vibration insulation is needed. It’s most commonly applied as thermal and sound insulation, available in the form of boards or granules. It’s also perfect for areas exposed to noise.

Its dark colour and natural texture also make expanded cork a popular decorative material, often used as a stylish finish for building façades.

Expanded cork is made up of millions of microscopic pores that trap air. These tiny air pockets are what keep interiors warmer in winter and cooler in summer. Together, they act as a natural thermal buffer, maintaining a stable and comfortable temperature throughout the year. In practice, this means lower energy consumption – there’s no need to crank up the heating in winter or rely on fans and air conditioning during hot days. The same micropores offer another benefit too – they’re excellent at absorbing sound. They muffle noises and reduce echoes, making your home quieter, calmer, and more comfortable.

In terms of thermal insulation, cork performs on par with popular building materials. Its thermal conductivity coefficient (λ) is around 0.036–0.040 W/mK, offering efficiency comparable to polystyrene or mineral wool. However, unlike those materials, cork is resistant to moisture, mould, fungi, and insects. It doesn’t warp or lose its insulating properties over time, making it a much more durable and long-lasting solution.

What’s more, cork is a safe material. It’s hypoallergenic and non-irritating, making it ideal for spaces used by people who suffer from allergies. When exposed to fire, it doesn’t melt or drip – instead, it chars without releasing toxic fumes. As a result, it doesn’t spread flames and helps reduce the risk of fire.

Expanded cork consists solely of cork granules and the natural resin that occurs within them. It contains no synthetic binders or toxic additives. When exposed to high temperatures, the granules fuse into a compact structure without the use of any chemicals. As a result, cork is safe for people, animals, and the environment. After many years of use, it can be recycled or simply left to decompose naturally, as it poses no threat to the ecosystem.

The process of obtaining cork is also completely sustainable. The material comes from the bark of the cork oak tree, which doesn’t need to be cut down to harvest it. The bark naturally regenerates every 9–12 years, and a single tree can provide raw material for over 150 years. It’s a cycle that perfectly fits the principles of a circular economy.

In addition, expanded cork has a negative carbon footprint – it absorbs more CO₂ than is emitted during its production. At a time when most building materials put a strain on the environment, cork stands as proof that it’s possible to build in a way that’s both modern and responsible.