Your Ultimate Guide To Cork Insulation: All You Need To Know

A segment of cork insulation sitting atop a full sheet.

Cork is an excellent alternative to bulkier insulation materials such as fiberglass and rock. As it is easily attainable, cork is an eco-friendly option for insulating the modern home. 

So what do you need to know before using cork insulation to increase your home’s energy efficiency?

If you are considering using cork insulation in your home and want to know if it is the right choice, this guide is for you. Read on to find out everything you need to know about cork insulation.

If you’d like to read about other types of natural insulation, take a look at our article on companies that make sheep’s wool insulation.

Qualities of Cork Insulation 

Cork is an inexpensive insulation material with an R-value rating higher than other alternatives. It is also a renewable and recyclable resource, making it perfect for building a sustainable home. In addition, the material offers high thermal resistance, is lightweight, and is easy to install.

Why Cork Insulation?

Cork is an excellent option for making homes more energy efficient and comfortable. Overall, it’s a cheap and eco-friendly building material, making it an ideal choice for homeowners who want to make the most of their investment.

While not entirely waterproof, cork has more water resistance than other insulators and is also a great soundproofing agent. Thus, it offers good insulation because it reduces noise and prevents condensation problems when moisture escapes from inside a wall or ceiling.

To better understand why cork works well for insulation, we can look at the R-value of other insulating materials and compare them with cork. 

Cork’s R-Value

The R-value of an insulation product measures its thermal resistance or ability to insulate. A higher R-value means better insulation properties and resistance to heat flow.

Closeup of a cork board insulation texture.
Cork brings a natural and warm look to any home.

Insulation products with higher R-values take longer to heat up but stay warm for longer after being heated. Conversely, products with lower R-values are more easily heated but cool down faster than high R-value insulation.

Insulation works by trapping pockets of air between materials that do not conduct heat or cold well. This quality prevents heat from escaping through walls and ceilings, which means heating and cooling the house requires less energy consumption, helping you save money on energy bills. 

The R-value is determined by measuring the thickness of a material and calculating its conductivity (how easily it conducts heat) using a formula that includes resistivity and temperature.

While figuring out any insulator’s R-value is straightforward, you need to pick an insulator with an appropriate R-value for your home environment. 

This value depends on several factors, including:

  • The climate in which you live
  • The layout of your home, including the number of floor levels and if there is a basement or attic
  • The dimensions of the rooms
  • Your home’s heating, ventilation, and air conditioning (HVAC) system

Cork has an R-value of 3.6-4.2 per inch. Overall, cork is one of the best insulators money can buy because it has a great R-value compared to other insulating materials. 

Cork vs. Fiberglass

Fiberglass insulation is made from glass fibers formed into mats, batts, or rolls, mainly used to construct walls and attics to provide thermal insulation. It works by trapping pockets of air between the fibers in the material so that heat cannot penetrate through it easily.

Fiberglass insulation being installed in the underside of a home attic ceiling, showing a beige fiberglass batt.
Fiberglass insulation is installed in a roof space.

Fiberglass insulation is a top choice for residential construction because of its superior insulating capabilities. It remains a popular choice among homeowners due to its cost-effective nature and ease of installation. 

Fiberglass insulation comes in two primary forms: 

  • Loose-fill – loose-fill fiberglass refers to fibers sprayed into a space between walls or floors. It is used primarily for basement walls or crawl spaces because it helps keep moisture out by stopping air infiltration through cracks, wires, and other penetrations through the wall or floor surface.
  • Blown-in – blown-in fiberglass uses larger pieces than loose-fill but must still be installed by a professional with specialized equipment—this application allows them to install it between wall studs or floor joists without crushing the material during installation.

When comparing fiberglass and cork insulation, the first thing that comes to mind is sustainability. As an all-natural and eco-friendly material, cork insulation is better for a homeowner’s carbon footprint than fiberglass.

Fiberglass is simple to install, but there are some disadvantages to using it compared to cork: 

  • Fiberglass has an R-value of 2.2-2.9 per inch, which is lower than cork – this value makes cork a superior insulator with better thermal resistance characteristics, as fiberglass has lower heat resistance. 
  • The R-value of fiberglass decreases over time due to the material sagging and settling – settled fibers create air pockets within the walls of your home, which can trap moisture and lower the material’s thermal conductivity. 
  • Fiberglass particles pose a health hazard during and after installation, unlike cork which is chemical-free – cork insulation is made from oak wood and water, which is safe for humans. On the other hand, glass fibers can irritate your skin and lungs if you handle the material without proper protective gear. 
  • Cork has a higher water resistance than fiberglass – fiberglass insulation does not prevent moisture from entering your home, so it requires an additional vapor barrier during installation, driving up costs. On the other hand, cork is naturally waterproof, and its high vapor permeability ensures that any moisture it absorbs dissipates quickly.  

Cork vs. Cellulose

Like cork, cellulose is gaining popularity as an eco-friendly and renewable option. Cellulose insulation is made from recycled newspapers and other organic waste products, making it a safe and affordable alternative to synthetic insulators. 

Unlike fiberglass, cellulose is made from natural materials. As a result, it has no harmful chemicals, so there’s no chance of toxic off-gassing if you have allergies or respiratory issues. Additionally, installing cellulose yourself is easy, so you don’t need to worry about hiring someone to do it for you. 

When blown into walls, floors, and attics with an airgun via holes in the wall or ceiling, cellulose insulation fills all voids in your home. This coverage includes spaces between frames and around pipes, thus creating a blanket of protection against heat loss.

A picture of grey loose-fill blown-in cellulose insulation with a top-down view. It's sitting in between two wood studs.
Blown-in cellulose insulation is good for insulating difficult-to-reach areas.

However, some drawbacks to using cellulose over cork include: 

  • Cellulose holds an R-value of 3.2-3.8 per inch, slightly lower than cork – cork has better water and thermal resistance than cellulose. 
  • Cellulose tends to settle over time due to gravity, while cork is compression-resistant – when cellulose settles and leaves open spaces, air pockets form and lower your home’s thermal resistance value.
  • Cellulose insulation is messy to install – unlike the relatively fuss-free cork, plenty of dust and debris gets left behind after installing cellulose insulation. 

Wear over time and settling are two of the most significant concerns for cellulose insulation. While it might provide adequate insulation and save money initially, homeowners pay more to maintain insulation in the long run. 

Reasons To Use Cork Insulation

Cork insulation is versatile and has many applications. 

Whether you’re building a new home or remodeling one, some reasons to consider using cork insulation instead of other materials include the following:

  • Soundproofing your home – cork has excellent soundproofing properties. If you want to reduce noise, select dense-grade cork that will block out sound waves more effectively than lighter grades do.
  • Cork is an excellent fire retardant due to its low combustion rate – cork also does not emit toxic gases or produce a flame during combustion. 
  • Cork insulation improves energy efficiency and air infiltration into your home – low-density cork enhances air circulation in your home but keeps the building warm during cold weather. 

Here are different types of cork insulation used for various installations:

  • Roof Insulation – cork panels are easy to install with a hammer and a few nails for roofing. Although the boards are lightweight and available in different thicknesses, using boards at least 6 inches thick is highly recommended. 
  • Floor insulation – you can also use corkboards to insulate floors by gluing panels on a concrete foundation. This method works best with carpeted floors. 
  • Gap insulation – you can use cork granules to fill gaps in ceilings, floors, and cavity walls. They are easy to insert because they range between 0.03-0.3 inches (1-10 millimeters) in thickness. 

Speak to a professional to get an opinion on cork insulation to choose the best type and thickness for your housing needs.

Closeup diagonal view from the corner of a piece of cork insulation.
Image courtesy of CorkLink.


Cork insulation is one of the best environmentally friendly options for reducing carbon footprint and increasing a home’s energy efficiency. Being a renewable resource, it is inexpensive and non-toxic, making it safe for families. 

Cork’s natural sound absorbency makes it an excellent choice for anyone looking to increase acoustics in their home or office. In addition, its easy installation will save you money on labor costs compared to other types of insulation.

For information on other types of sustainable building materials, see our article entitled “23 Sustainable Building Materials You Can Use Today.”

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