Is Epoxy Waterproof and can it be used as a Waterproof Membrane?

Is Epoxy Waterproof and can it be used as a Waterproof Membrane?

Epoxy Flooring and Its True Capabilities in Waterproofing

Key Takeaways

  1. Water Resistance vs. Waterproof: Epoxy provides significant water resistance but is not completely waterproof, especially in extreme conditions.
  2. Factors Affecting Epoxy Performance: The type of epoxy, curing process, and application greatly influence its water resistance capabilities.
  3. Unsuitable for High Pressure: Epoxy is not recommended for areas facing high hydrostatic pressure, like basements, where more robust solutions are needed.
  4. Vulnerability Over Time: Exposure to harsh environmental factors can diminish the water resistance of epoxy coatings.
  5. Professional Guidance Recommended: Consulting with licensed professionals and exploring alternative solutions is crucial for critical waterproofing needs.

What does “Waterproof” actually mean?

Before starting, it’s crucial to acknowledge the elusive nature of absolute waterproofness.

No material exists that’s impervious to water under extreme conditions. The term “waterproof” often signifies the material’s ability to withstand sustained water exposure without significant water absorption or damage.

So, while epoxy may not be a perfect aquatic superhero, it possesses valuable water-resistant qualities.

Regardless of its specific waterproof grading, the more relevant question is: “Can I use it as a waterproof membrane to repair or prevent water penetration?” 

The Alchemy of Water Resistance: Epoxy’s Inner Workings

The secret behind epoxy’s water resistance lies within its chemistry. When cured, the resin forms a dense network of cross-linked polymers, effectively barring water molecules from entry.

This characteristic makes it a valuable ally for protecting countertops, coating floors, and even performing underwater repairs.

I recently conducted a short experiment to show epoxy’s waterproof performance in the ultimate arena… underwater.

Play Video

Unveiling the Nuances: Factors Influencing Epoxy’s Water Barrier

However, epoxy’s water resistance isn’t a monolithic characteristic. Several factors influence its effectiveness:

  • Epoxy Selection: Different formulations boast varying degrees of water resistance. High-solids epoxies with minimal fillers generally excel. Marine-grade epoxies, specifically designed for aquatic environments, reign supreme in this domain.
  • Curing Alchemy: Improper curing, mainly due to moisture contamination, can disrupt the cross-linking process, creating pathways for water infiltration. Maintaining precise temperature, humidity, and ventilation during curing is essential.
  • Surface Preparation: Setting the Stage for Success

The substrate’s condition significantly impacts adhesion and performance. Ensuring proper cleaning, degreasing, and roughening of the surface enhances the bond, minimizing potential water entry points.

Thickness and Application: Building a Robust Barrier

Applying sufficient epoxy thickness and ensuring a seamless application with proper overlaps and edge sealing is crucial for creating a continuous, water-resistant barrier.

Time’s Relentless March: The Long-Term Perspective

Even high-quality, meticulously applied epoxy experiences degradation over time, especially when exposed to harsh weather conditions like UV radiation or extreme temperatures. This can affect its water resistance in the long run.

Beyond the Surface: Limitations of Epoxy as a Waterproof Membrane

While epoxy offers valuable water resistance, it has limitations as a primary waterproof membrane, particularly in specific scenarios:

High Hydrostatic Pressure: When Water Pushes Back

Epoxy isn’t suitable for applications like basements or foundations directly exposed to high hydrostatic pressure (water pushing against the structure).

In such cases, dedicated waterproofing membranes designed to handle specific pressure levels are essential for safeguarding the structure’s integrity.

Cracks and Movement: The Shifting Landscape

Concrete substrates are prone to cracking due to thermal expansion and contraction. These cracks can compromise the epoxy’s watertightness, allowing water infiltration.

In such scenarios, reinforcement with membranes specifically designed to accommodate movement might be necessary.

Chemical Warfare: Understanding the Enemy

Depending on their concentration and exposure duration, specific chemicals can degrade epoxy over time and affect its water resistance.

Choosing an epoxy resistant to the expected chemical exposure is crucial for lasting effectiveness.

Alternative Warriors: Exploring the Waterproofing Arsenal

For applications demanding superior waterproofing performance, several alternatives outperform epoxy:

  • Bituminous Membranes: These flexible, durable membranes offer excellent resistance to water, pressure, and chemicals, making them well-suited for foundations, basements, and roofs.
  • Liquid Applied Waterproofing (LAW): These single or two-component coatings form a seamless, elastomeric barrier, ideal for complex geometries and intricate waterproofing details.
  • Drainage Matting: Working in conjunction with membranes, drainage matting facilitates waterflow away from the structure, further enhancing the waterproofing system’s effectiveness.

The Verdict: A Balanced Perspective

While not all epoxies are created equal, and none offer absolute waterproofness, certain formulations can provide good water resistance when properly applied and under the right conditions.

However, for critical waterproofing applications involving high hydrostatic pressure, potential movement or community building schemes dedicated waterproofing membranes designed for specific performance requirements are typically the best choice.

Often people are looking to epoxy coatings to work as waterproof membranes on areas such as unit balconies, particularly over tiles, or on block retaining walls, where pre-existing, old membranes may have failed. Saving money on the cost of repairs is a very common motivation for people investigating epoxy to be used as a waterproof membrane.

I regularly get calls from people that have had water issues on an apartment balcony or rooftop terrace.

These areas are commonly tiled and the owners have received a shock at the price of removing the tiles, installing a new waterproof membrane and then replacing the tiles.

So they question if placing epoxy over the tiles, since it can have excellent water resistant properties, is a cheaper solution.

This becomes a tempting proposition because, as we have seen above, epoxy can be waterproof, but should you use it in this application?

My answer to this question is no under the following circumstances:

  1. If you need to have the work certified or
  2. Even if certification is not required, but you need to be certain that the waterproof membrane will be adequate.

In Australia we have trade qualified, Government-licenced waterproofers whose responsibility it is to provide membranes that can be guaranteed. These contractors have been trained for years to learn the correct techniques to provide a membrane that will keep water where you want it.

They typically use different products to what licenced epoxy installers use and they will install a product specifically tailored to your particular environment.

This level of expertise and surety does come at a price but unfortunately trying to save money when it comes to critical waterproofing is fraught with danger.

The problem is that even though epoxy can have excellent waterproof properties unless that membrane is installed perfectly seamless, and without even one tiny hole or minute blemish in it, then water will enter that hole. Once water enters it will cause the epoxy to lift and then your waterproof membrane is useless.

In addition to this unless the epoxy is installed by a licenced waterproofer, it can not be certified.

A licenced waterproofer can provide Government certification for their work, are insured appropriately and can be liable for failures.

Ultimately, consulting with a licenced professional to assess your specific needs and recommend the most suitable solution is advisable.

Remember, navigating the watery realm requires careful consideration, the right tools for the job and the correct tradesperson.

Related FAQs

  • Can I use Epoxy in my bathroom or shower?

    It is technically possible for us to coat tiled areas such as showers and bathroom floors.

    However, as the article concludes, using it in a shower or other wet areas is a dangerous situation because of the chance of the coating delaminating.

    We will coat a bathroom floor, but we do not install epoxy flake floors in showers.

  • Can I use epoxy to waterproof a basement wall?

    While it can be used for this purpose, we don’t recommend it. Instead, we suggest you consult a licensed waterproofer to advise on the most suitable waterproof membrane for this job.
  • Can an Epoxy Flake Floor be installed on top of a waterproof membrane?

    Yes, this can be done, but before you install the membrane, please contact us so we can liaise with your installer and check that our products are compatible with theirs.
  • How long do I have to wait after installing a waterproof membrane to get my epoxy coating applied?

    Generally speaking, we can install our epoxy systems within 24 hours of the membrane being installed.
  • If my house floods can Epoxy Flake Flooring be hosed out or pressure cleaned?

    Yes, you can do either, but we suggest that you keep petrol-powered pressure washers a minimum of 500mm above the floor due to their extreme power.

Related FAQs

About the Author

Tim McGary

Tim McGary, a notable figure in the construction industry since the Y2K era, pioneered Same Day Epoxy Flooring Systems in Australia. His expertise extends to polished concrete and single-colour industrial floors. Celebrated as the Australian Installer of the Year from 2021 to 2023, he now excels in creating full fake seamless epoxy floors for both residential and commercial spaces. Renowned for having the most 5 Star Google reviews in his field, Epoxy Flooring Co. blend Tim’s extensive knowledge and skills, ensuring every project is completed with precision and on time.

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