Cork Insulation Guide: Definition, Benefits, and More!

Insulating your wall with Cork

From reducing airflow and noise nuisance to controlling moisture, insulation plays a crucial role in enhancing the comfort of your living space. 

While these materials help you save energy, the gas emitted during the manufacturing process can negatively impact the environment. Not to mention, popular options, like fibreglass, can have potential health hazards.

This is where cork insulation stands out as an eco-friendly alternative, offering a safer insulation option, especially for those with allergies.

Continue reading this cork insulation guide to learn about its origins, advantages, and disadvantages.

What Is Cork Insulation?

Cork is a sustainable and eco-friendly material that has many versatile applications. Derived from the bark of Mediterranean oak trees (Quercus suber), this natural material can be harvested every 9-12 years. 

This harvesting is done only once the plant reaches a maturity of 30-40 years. Interestingly, stripping this cork-rich bark helps the trees become more vigorous and improves their health.

So, what makes cork special and ideal for insulation?

Naturally, this plant-based material has a honeycomb-like structure. This provides the cork with heat-resistance properties, making a great insulation option.

How Is Cork Insulation Made?

Like sheep’s wool insulation, cork is a natural product. Manufacturing these boards doesn’t require any chemicals — a trait that makes it an excellent solution for those with allergies.

Regardless of the product, cork insulation production involves recycling waste bark material. The factories collect leftover chips and branches to create the insulation board. They use steam to heat the cork granules and press them into various thicknesses.

The best part? No binding agents or additives are added. The high temperature expands the cork and activates a natural binder, suberin. This polymeric chemical acts as a glue, holding the granules together.

Types of Cork Insulation

Generally, there are four types of cork insulation that you can purchase. These are granules, insulation rolls, expanded boards, and spray. Each form has its properties and applications. Here’s a brief explanation of each type:

  1. Cork Granules

As the name suggests, cork granules are small, grainy materials. They usually have a size range of 1-10 millimetres. Thanks to their compact structure, these grains are easy to work with. 

While you can’t use them to cover large surface areas, these loose materials still have many applications. Typically, cork granules are used to fill gaps, such as wall cavities. To apply these grains, the installer uses the insufflation method. 

Basically, this technique involves blowing the granules into ceilings and floors to fill holes. This helps reduce air infiltration and, thus, saves energy. On the flip side, this form is more expensive than the other options.

  1. Cork Insulation Rolls

At first glance, you might think cork-rolled insulation is just uncut panels. However, that’s not true.

These rolled sheets are generally thinner than cork board insulation, typically having a thickness of 5 millimetres or less. They’re also more flexible.

For that reason, rolled insulation is more suitable for limited-space rooms. You can use these sheets as an underlay for carpets. You can also use them for floors and roofs. 

However, it’s worth mentioning that this insulation type is less energy efficient than thick, rigid panels.

Still, rolled insulation has many perks. For starters, they add pleasant, rustic aesthetics to your house, which never really goes out of style.

Additionally, these insulators are easy to DIY. All you need to do is apply adhesive to an area and roll the cork onto it. 

  1. Expanded Cork Insulation

Expanded cork insulation, or semi-rigid,  is among the popular cork choices thanks to its versatility.These types of boards are thick, reaching up to 50 millimetres. 

Some manufacturers even sell thicker boards, which are more suitable for roofs. Don’t be fooled by their size; these boards are light in weight. 

All these perks make them excellent thermal insulators, having an R-value between 3.4 and 7.1, depending on the thickness.

Aside from that, semi-rigid cork boards have fire-retardant and soundproofing properties. Not to mention, they are naturally dark. So, you can use them as a decorative finish to achieve a contemporary look.

  1. Sprayed Cork Insulation

Like spray foam, cork insulation can also come in liquid drop form. However, this product is relatively new. Still, you can apply it almost to any surface, from roofs to basements. You can even use it to fill cavities!

Aside from that, spray cork provides an excellent seal that helps fight off pests and mould.

Since this product is a spray, you might wonder if it’s natural. The short answer is yes. 

The insulation is around 80% cork. To achieve this liquid texture, manufacturers mix it with water-based resins. It may also contain non-toxic, natural paint.

While you can DIY this type of cork insulation, it’s best to leave the job to contractors. That’s because, unlike spray foam, this product doesn’t expand. You need to have some skills to achieve a uniform coat.

Why Choose Cork Insulation?

Several perks make cork an excellent insulation option. For one, it provides decent thermal and sound insulation. Additionally, it’s durable and environment-friendly. Not to mention, it resists water and fire.

Let’s dig deeper into cork insulation advantages!

  1. Energy Efficiency

Since the primary purpose of insulation is to reduce energy, it’s no surprise that cork can help you cut down on those energy bills. As you might know, heating, ventilation, and air conditioning systems (HVAC) consume a lot of energy. 

In fact, controlled air conditioning alone accounts for 40% of the UK’s energy consumption. Despite that, these systems only take up to 10% of the UK’s electricity, all thanks to insulation.

So, how does cork prevent wasting energy?

As previously mentioned, this natural product has a honeycomb-like structure. These closed cells trap air. Since air has poor thermal conductivity, these molecules create a barrier, preventing heat flow. As a result, they help maintain your home’s internal temperature, ensuring your HVAC remains efficient.

  1. Sound Insulation

Not only does the trapped air in the cork act as a thermal insulator, but it also helps with soundproofing. How?

Well, that’s mainly due to the different densities. When sound waves meet larger air densities, they lose energy. Some of it is lost as heat or reflects to the source. Regardless, this causes the waves to not pass the barrier. 

So, adding that layer of cork insulation can help prevent outside noise from disturbing your peace!

  1. Durability

Cork insulation is highly durable. Again, this longevity has to do with the bark’s natural structure.

Since it has a compact cell arrangement, cork holds many gases. This provides it with high elasticity, allowing it to compress and reach half of its thickness. It can also return to its original shape without being damaged.

This flexibility makes the insulation shock-proof. As a result, it maintains structural integrity, lasting up to 50 years or more with proper maintenance.

  1. Control Moisture

Moisture resistance is one of the most important features of any insulation. If the layer doesn’t resist water, it can cause several problems. Among the primary issues is mould growth. 

As you might know, these microorganisms thrive in a wet environment. Since cork has a compact cell structure, it can prevent rainwater from seeping into your house. 

What’s more, this natural material has suberin, as mentioned earlier. That waxy chemical is hydrophobic, meaning it is insoluble in water. 

Sure, that doesn’t make cork 100% water-proof, but it can resist the liquid, reducing moisture damage.

  1. Fire Resistance

Generally, most commercial insulators are treated with fire-retardant chemicals to slow down flare-ups. However, not all insulators resist fire equally. 

For instance, rigid foam and other plastics are highly flammable. Without these retardants, these insulators will catch fire easily. That’s not the case with cork. 

In nature, cork acts as a protective layer, shielding trees from hot climates. Research shows that it remains stable at temperatures as high as 200ºC. 

What’s more, this elastic material has weak combustion properties. It burns slowly and doesn’t emit toxic gases. So, it’s less likely to produce dangerous flames and cause fire to spread.

  1. Environmentally Friendly

What sets cork insulation apart from other artificial types is that it’s eco-friendly and sustainable, since it comes from oak trees. 

Aside from that, refining the bark doesn’t require heavy processing. No toxic chemicals go into the mix, either. So, it doesn’t pollute the environment—unlike plastic insulation, which can leak VOCs.

What’s more, since this material is 100% natural and biodegradable. Typically, it takes 3 to 10 years for the material to decompose.

What Are the Disadvantages of Cork Insulation?

Although cork insulation has several perks, that doesn’t mean it’s perfect. Cost is probably the primary disadvantage.

While the price may vary depending on several factors, like thickness and region, generally, cork insulation is expensive. 

You can find other eco-friendly options that are more affordable, like sheep wool. Aside from that, applying thick boards to exterior walls may require special treatments around vents, windows, and doors. These additional steps can add up to the total cost.

Cork Insulation Conclusions

As you can see, cork insulation is an excellent option for those looking for an eco-friendly product. Aside from contributing to a greener environment, this material brings several perks. 

Not only does it control moisture and reduce those energy bills, but it also has soundproofing properties.What’s more, thanks to its structure, this material is fire-resistant and durable, lasting for several decades.

If you’re ready to transform your home’s energy efficiency with cork insulation, Insulation Advisor has you covered. Request your quote today and embark on your journey to a greener living space!

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