Is Cork Underlayment Waterproof – Find Out

Cork underlayment is a popular choice in flooring installations for its unique properties and numerous advantages. Is cork underlayment waterproof? While cork itself is naturally resistant to moisture, it’s important to note that cork underlayment is not entirely waterproof. 

Cork underlayment is not inherently waterproof, but it does exhibit water-resistant properties. While cork is naturally resistant to moisture, it is essential to recognize that prolonged exposure to standing water or excessive moisture can compromise its effectiveness. 

Furthermore, cork underlayment is best suited for areas with moderate moisture levels, providing a reliable barrier against everyday spills and humidity. Understanding its characteristics helps in making informed decisions about its usage in different flooring applications.

Is cork water-resistant?

Is cork water-resistant

Cork is naturally water-resistant to some extent, thanks to its unique cellular structure. The suberin, a waxy substance present in cork, acts as a natural barrier against moisture. 

This property makes cork suitable for applications where exposure to water or humidity is limited. However, it’s important to note that cork is not entirely waterproof.

In everyday situations, cork can withstand spills and occasional exposure to moisture without sustaining damage. This makes it a popular choice for flooring in areas such as kitchens or bathrooms where occasional spills may occur. 

Additionally, cork’s water resistance helps prevent the growth of mold and mildew.

Despite these advantages, prolonged exposure to standing water or extreme moisture can still lead to damage, affecting the structural integrity of cork. Therefore, while cork is water-resistant and can handle normal humidity levels, it’s crucial to avoid submerging or subjecting it to excessive moisture for extended periods. 

Proper sealing and maintenance can enhance cork’s water-resistant properties, ensuring its longevity and performance in various applications.

How to make cork waterproof

Making cork fully waterproof involves applying a sealant or coating to enhance its natural water-resistant properties. Here’s a step-by-step guide on how to make cork waterproof:

  1. Clean the Surface:

Before applying any sealant, ensure that the cork surface is clean and free from dust, debris, and any contaminants. Use a mild cleaner or a mixture of water and mild detergent to clean the cork thoroughly. Allow it to dry completely before proceeding.

  1. Choose the Right Sealant:

Select a high-quality, water-resistant sealant suitable for cork surfaces. Polyurethane, acrylic, or wax-based sealants are commonly used for cork. Make sure the chosen sealant is compatible with cork and suitable for your specific application.

  1. Test in an Inconspicuous Area:

Before applying the sealant to the entire cork surface, perform a small test in an inconspicuous area to ensure compatibility and to observe any potential changes in color or texture.

  1. Apply the Sealant:

Using a brush, roller, or spray applicator, apply the sealant evenly over the entire cork surface. Follow the manufacturer’s instructions regarding the number of coats required and the drying time between coats. Pay special attention to seams and edges.

  1. Allow for Proper Drying:

Allow the sealant to dry thoroughly between coats and after the final application. This process may take several hours or even days, depending on the type of sealant used. Ensure good ventilation during the drying process.

  1. Reapply if Necessary:

Depending on the level of waterproofing desired and the type of sealant used, you may need to reapply the sealant periodically. Follow the manufacturer’s recommendations for maintenance and reapplication.

  1. Consider Waxing:

In addition to sealants, some may choose to apply wax to further enhance waterproofing. Beeswax or specialized cork wax can be used to create an additional protective layer.

  1. Regular Maintenance:

To preserve the waterproofing and overall condition of the cork, practice regular maintenance. Clean up spills promptly, avoid prolonged exposure to standing water, and use gentle cleaning methods to prevent damage to the sealed surface.

Keep in mind that while these steps can enhance cork’s resistance to water, complete waterproofing may not be achievable, and it’s essential to consider the specific characteristics of the sealant used. 

Related Post: Is Cork Fire Resistant?

What happens if cork underlayment gets wet?

What happens if cork underlayment gets wet

If cork underlayment gets wet, its performance and structural integrity may be compromised, and various issues can arise. Here are some potential consequences of water exposure to cork underlayment:

  1. Expansion and Contraction:

Cork is a natural material that can absorb moisture, leading to expansion. When wet, cork underlayment may swell, and if the moisture content is not reduced, it can result in permanent changes in size and shape. As the cork dries, it may contract, causing gaps or buckling.

  1. Mold and Mildew Growth:

Prolonged exposure to moisture can create favorable conditions for mold and mildew growth. Mold not only damages the cork but can also pose health risks and contribute to indoor air quality issues.

  1. Degradation of Adhesives:

Cork underlayment is often installed using adhesives. Water exposure can weaken these adhesives, leading to a loss of bonding strength between the cork and the subfloor. This can result in the underlayment lifting or separating from the subfloor.

  1. Odor and Discoloration:

Wet cork may develop an unpleasant odor, and prolonged exposure to moisture can cause discoloration. Stains and dark spots may appear on the surface, affecting the aesthetic appeal of the cork underlayment.

  1. Structural Weakening:

Over time, continuous exposure to water can weaken the structural integrity of the cork fibers. This weakening can reduce the underlayment’s ability to provide support and insulation, impacting the overall performance of the flooring system.

  1. 6. Loss of Insulation Properties:

Cork is valued for its natural insulating properties. When wet, the insulation effectiveness of cork underlayment may diminish. This can impact the thermal and sound insulation benefits that cork is known for in flooring applications.

To mitigate these issues, it’s crucial to address water damage promptly. If the cork underlayment becomes wet due to a spill or water intrusion, it should be thoroughly dried as soon as possible. 

Adequate ventilation, dehumidification, and, in some cases, the replacement of damaged sections may be necessary. Preventative measures, such as using water-resistant sealants and avoiding excessive moisture in the installation area, can also help protect cork underlayment from potential water-related problems.

Does cork underlayment absorb water?

Yes, cork underlayment can absorb water to some extent due to the natural properties of cork. Cork is a porous material with a cellular structure that includes pockets of air. 

These pockets are filled with a substance called suberin, which is waxy and water-resistant. While suberin provides cork with inherent water resistance, it does not make cork completely waterproof.

When exposed to moisture, cork underlayment can absorb a certain amount of water into its cellular structure. This absorption is typically limited and depends on factors such as the duration of exposure, the intensity of the water source, and the overall quality of the cork material.

It’s important to note that the water absorption of cork can lead to temporary changes in its size and shape, causing expansion. 

However, cork has the ability to release moisture and return to its original state as it dries. This natural resilience to moisture makes cork underlayment suitable for areas with occasional spills or moderate humidity levels.

To enhance water resistance and protect cork underlayment from potential water-related issues, it is common practice to apply sealants or coatings. 

These sealants create an additional barrier, reducing the extent to which the cork absorbs water and providing added protection against water damage.

Is cork flooring waterproof?

Is cork flooring waterproof

Cork flooring is not inherently waterproof, but it does possess natural water-resistant properties. The cellular structure of cork contains suberin, a waxy substance that makes cork resilient to water to some extent. This feature allows cork flooring to withstand occasional spills and exposure to moisture in everyday situations, such as in kitchens or bathrooms.

While cork flooring is water-resistant, it is essential to note that prolonged exposure to standing water or excessive moisture can still lead to damage. In areas prone to frequent and substantial water exposure, it is advisable to take precautions and use additional sealants or finishes designed to enhance water resistance.

To make cork flooring more resistant to water, sealants or coatings can be applied. These finishes create an additional protective layer that reduces the risk of water absorption and enhances the flooring’s overall durability.

Is cork material waterproof?

Cork is not completely waterproof, but it does have water-resistant properties. Cork is derived from the bark of cork oak trees and contains a waxy substance called suberin, which helps make it resistant to water and moisture. This natural property makes cork somewhat water-resistant, but it is not entirely impervious to water. 

While cork can withstand occasional exposure to water, prolonged or frequent contact with moisture may lead to damage or deterioration.

It’s important to note that the level of water resistance can vary depending on the quality of the cork and how it’s processed or treated. 

Additionally, using sealants or coatings designed for cork can enhance its water resistance. If you have specific items or products made of cork, it’s advisable to check the manufacturer’s recommendations for care and maintenance to ensure the best performance.

Does cork get ruined by water?

Cork is water-resistant to some extent due to the presence of suberin, a natural waxy substance in its cellular structure. This property helps cork withstand occasional exposure to water, making it suitable for certain applications. However, it is crucial to understand that cork is not completely impervious to water.

Prolonged or frequent contact with water can lead to several issues with cork:

  1. Absorption and Swelling: Cork can absorb water over time, causing it to swell. This can result in changes to the material’s structure, leading to deformation, warping, or loss of its original shape.
  2. Mold and Mildew: Excessive moisture can create a favorable environment for the growth of mold and mildew on cork surfaces. This can not only compromise the appearance of the cork but also affect its integrity.
  3. Degradation of Adhesives: If cork is used in conjunction with adhesives or laminates, prolonged exposure to water may weaken the bonds, causing layers to separate or peel.
  4. Discoloration: Water exposure can cause cork to discolor, leading to stains or changes in its original color.

To preserve and protect cork items from water damage, it’s advisable to:

  • Apply Sealants: Utilize sealants or coatings specifically designed for cork to enhance its water resistance.
  • Avoid Prolonged Exposure: Minimize prolonged exposure to water and moisture, especially for items like cork flooring or coasters.
  • Regular Maintenance: Clean and dry cork items regularly to prevent the accumulation of moisture.

How long does cork last in water?

How long does cork last in water

The longevity of cork in water depends on various factors, including the quality of the cork, the specific application, and the duration and conditions of water exposure. While cork has natural water-resistant properties due to the presence of suberin, it is not impervious to water and can be affected over time.

Here are some general considerations:

  1. Short-Term Exposure: Cork can generally withstand short-term exposure to water without significant damage. For example, if you accidentally spill water on a cork surface or use cork coasters, the material is likely to recover well with minimal impact.
  2. Prolonged Exposure: Extended or frequent contact with water can lead to issues such as swelling, deformation, and the growth of mold or mildew. In applications where cork is consistently exposed to water, such as flooring, the longevity may be reduced compared to dry environments.
  3. Quality and Treatment: The quality of the cork and any treatments applied (such as sealants or coatings) can influence its durability in water. High-quality cork and proper protective measures can enhance its ability to resist water damage.
  4. Maintenance: Regular cleaning and proper maintenance can also play a role in extending the life of cork in water. Promptly drying cork surfaces and addressing any water-related issues can help prevent long-term damage.

How do you waterproof a cork?

Waterproofing cork involves applying protective coatings or sealants to enhance its natural water-resistant properties. Here are step-by-step instructions for waterproofing cork:

Materials Needed:

  • Cork item or surface
  • Mild detergent or cork cleaner
  • Fine-grit sandpaper (optional)
  • Clean, lint-free cloths or rags
  • Waterproof cork sealant or coating (polyurethane, wax, or specialized cork sealant)
  • Paintbrush or applicator pad
  • Ventilated workspace


  • Clean the Cork:
    • Start by cleaning the cork surface thoroughly to remove any dirt, dust, or contaminants. Use a mild detergent or cork cleaner and a soft cloth. Gently scrub the cork, and then wipe it dry.
  • Sand (if necessary):
    • If the cork surface is rough or uneven, you may choose to lightly sand it with fine-grit sandpaper. This step is optional and depends on the specific requirements of the cork item.
  • Choose the Right Sealant:
    • Select an appropriate waterproofing sealant for cork. Options include polyurethane sealants, wax sealants, or specialized cork sealants available in the market. Ensure that the chosen sealant is compatible with cork.
  • Ventilation:
    • Work in a well-ventilated area to ensure proper air circulation during the application of sealant.
  • Test in a Small Area (Optional):
    • Before applying the sealant to the entire cork surface, it’s advisable to test it in a small, inconspicuous area to ensure compatibility and to observe any potential changes in color or texture.
  • Apply the Sealant:
    • Stir or shake the sealant as per the manufacturer’s instructions. Using a paintbrush or an applicator pad, apply a thin, even layer of the sealant to the cork surface. Ensure that the entire surface is covered.
  • Allow to Dry:
    • Follow the recommended drying time specified by the sealant manufacturer. This duration may vary depending on the type of sealant used.
  • Apply Additional Coats (Optional):
    • If necessary, you can apply additional coats of sealant for increased water resistance. Allow each coat to dry before applying the next.
  • Buff or Polish (Optional):
    • Once the final coat is completely dry, you may choose to buff or polish the cork surface with a clean, dry cloth to enhance its appearance.
  • Regular Maintenance:
    • To preserve the waterproofing effect, practice regular maintenance by cleaning the cork surface with a mild detergent and promptly addressing any spills or water exposure.


Finally, is cork underlayment waterproof? Cork underlayment is not inherently waterproof, but it does possess natural water-resistant properties. The water resistance of cork underlayment is mainly due to the presence of suberin, a waxy substance in cork’s cellular structure. 

While cork can resist moisture to a certain extent, it is important to note that it is not completely impervious to water.

In applications where the underlayment may be exposed to occasional spills or moisture, cork can provide adequate protection and may recover well from short-term exposure. 

However, prolonged or frequent contact with water can lead to issues such as swelling, deformation, and a decrease in performance.

To enhance the water resistance of cork underlayment, some products may be treated with sealants or coatings during the manufacturing process. These treatments can further improve the underlayment’s ability to repel water.