Epoxy Waterproofing: Properties, Usage, Installing and Protection

Written By Adam Paul – Waterproofing Expert

Epoxy is scientifically named as polyepoxide. Polypexides are a class of reactive prepolymers and polymers that contain epoxide groups. Epoxy is a combination of epoxy resin and epoxy hardener. After combining epoxy resin and hardener, it forms a solid compound.

Epoxy is a waterproof compound. Waterproof epoxy is a water-dissolved, limited flexible, UV-resistant, and durable coating that can be used for positive and negative-side waterproofing, such as floors, walls, ceilings, roofs, cracks, joints, pipes, and tanks.

The thickness of the epoxy waterproofing layer varied between 0.5mm to 3mm. You should apply at least 3 coats on the surface for better protection. After you install an epoxy waterproofing, you should cure it minimum of 3 days by applying all the other coatings.

The epoxy waterproofing coating consists of bisphenol-A (BPA) or bisphenol-F (BPF). Epoxy resin lasts between 10 to 15 years. Epoxy is not a breathable waterproofing membrane, but it is a flexible and UV-resistant coating. Hence, epoxy waterproofing can be used to waterproof concrete, cement, metal, wood, bricks, and stones. The epoxy waterproofing coating is strong and slip-resistant. Hence, it can be used to waterproof basements, basement walls, bathroom floors, swimming pools, slabs, fountains, toilets, and terraces.

You can apply the epoxy waterproofing as a DIY project in your home. Before applying the epoxy waterproofing layer on the surface, you should prepare the surface by cleaning, drying, and free from any dust, dirt, oil, or grease. You should remove any existing paint or coatings on the surface. Then you can apply the epoxy waterproofing coating using a brush, spray, or roller. After you apply the epoxy sealant, you should keep it curing for about 24 hours.

Epoxy waterproofing layer can be damaged due to physical impacts, incorrect mixing and applications, and is open to extreme temperatures, chemicals, and UV rays. You can protect the epoxy waterproofing coating by regular cleaning, avoiding heavy impacts, limiting exposure to sunlight, recoating, avoiding harsh chemicals, and regular inspections.

You can use polyurethane waterproofing instead of epoxy waterproofing. But both of these waterproofing methods have different performances.

Is Epoxy Waterproofing?

Yes, epoxy is a waterproofing compound that consists of two main components: epoxy resin and epoxy hardener. Waterproof epoxy is a water-dissolved, limited flexible, UV-resistant, and durable coating that can be used for positive and negative-side waterproofing such as floors, walls, ceilings, roofs, cracks, joints, pipes, and tanks.

Epoxy waterproofing is available as epoxy resin, cement, paint, grout, putty, sealant, glue, and primer. These epoxy waterproofing adhesives are available in order to easy to apply, reduce curing time, improve cost-effectiveness, and be compatible with surface conditions.

What is the Thickness of Epoxy Waterproofing?

The thickness of epoxy waterproofing is the cured dry film thickness (DFT) of an epoxy resin coating applied to a substrate to create a seamless, non-porous, water-resistant barrier. The thickness of the epoxy waterproofing depends on the surface flatness and the purpose of the surface. So Aqviz experts maintain three main thicknesses in EPOXY waterproofing.

3 Main Thicknesses and their Usage of Epoxy Waterproofing

• Thin-film epoxy coating: 0.5-1.0 mm (0.020-0.039 in)
  We use this range for damp-proofing interior floors and walls where hydrostatic pressure stays low, examples include residential bathrooms and utility rooms.
• Medium-build epoxy waterproofing: 1.0-2.0 mm (0.039-0.079 in)
  This is our most common spec at Aqviz for basements, balconies, and plant rooms where intermittent water exposure and cleaning cycles occur.
• High-build epoxy waterproofing: 2.0-3.0 mm (0.079-0.118 in)
  We recommend this thickness if standing water, abrasion, or chemical washdowns occur, examples include parking decks, industrial floors, and water-retaining slabs.

How Long Does Epoxy Waterproofing Take to Cure?

Epoxy waterproofing curing time is the total period required for an epoxy coating to chemically cross-link, harden, and achieve water resistance, mechanical strength, and adhesion to the substrate.

There are 4 main epoxy curing time stages for waterproofing applications.

• Initial set time: 6-12 hours (0.25-0.50 days)
  The epoxy becomes tack-free and stops flowing. We allow light foot traffic only if the manufacturer permits.
• Recoating window: 12-24 hours (0.5-1 day)
  We apply the next coat within this window to ensure chemical bonding without surface grinding.
• Water exposure resistance: 24-72 hours (1-3 days)
  The coating resists splashing and intermittent moisture. We never allow ponding at this stage.
• Full chemical cure: 5-7 days (120-168 hours)
  The epoxy reaches maximum hardness, adhesion, and waterproofing performance. We open the area for full service only after this period.

What Factors Affect Epoxy Waterproofing Curing Time?

There are 7 major factors that influence epoxy waterproofing cure duration.

• Ambient temperature: Cold conditions below 10 °C (50 °F) slow polymerization, while ideal curing occurs at 20-30 °C (68-86 °F).
• Relative humidity: High humidity above 80 % RH delays surface cure and may cause amine blush on the coating.
• Epoxy formulation: Fast-cure epoxies set within 8-12 hours, while standard systems require 24 hours per coat.
• Coating thickness: Builds above 1.5 mm (0.059 in) per coat increases internal heat and extends cure time.
• Substrate moisture content: Concrete moisture above 4 % or vapor emission beyond 3 lb/1,000 ft²/24 h (1.36 kg/93 m²/24 h) slows curing and weakens bonding.
• Ventilation rate: Poor airflow traps solvents and heat, extending curing by 12-24 hours.
• Mixing ratio accuracy: Deviations beyond ±2 % resin-to-hardener ratio cause soft spots or incomplete curing.

How Many Coatings Should You Apply Epoxy Waterproofing?

Epoxy waterproofing coating count is the number of epoxy layers required to achieve a continuous, pinhole-free, and pressure-resistant waterproof barrier on a substrate. The total number of epoxy waterproofing is 3-4 coats, but it depends on the nature of the water exposure area. As well as you should apply 3 standard coats on the surface as follows.

3 standard coating layers used in epoxy waterproofing systems.

• Primer coat: 1 coat
  This coat penetrates concrete pores and improves adhesion. We apply it at 0.2-0.3 mm (0.008-0.012 in) thickness to lock down dust and surface laitance.
• Base waterproofing coat: 1-2 coats
  These coats form the main waterproof barrier. Each coat builds 0.5-1.0 mm (0.020-0.039 in) dry film thickness depending on epoxy viscosity and roller type.
• Top seal or protection coat: 1 coat
  This coat improves abrasion resistance, chemical stability, and UV tolerance. Typical thickness stays around 0.3-0.5 mm (0.012-0.020 in).

What Are the Compounds of Epoxy Waterproofing?

The epoxy waterproofing consists of 4 main compounds such as epoxy resin, curing agent or hardener, modifiers and additives, and solvents.

1. Epoxy resins improve the durability and strength of the final coating. Epoxy resin consists of bisphenol-A (BPA) or bisphenol-F (BPF).
2. Epoxy hardener should be mixed with epoxy resin. After mixing epoxy resin and hardener, initiate a chemical reaction that forms a solid layer. The final epoxy sealant is a solid, hard, strong, and limited flexible coating due to the epoxy hardener.
3. Epoxy additives and modifiers include flexibilizers to increase flexibility, fillers to enhance strength or reduce cost, thickeners to adjust viscosity, and pigments for coloration.
4. Solvents in epoxy are used to adjust the viscosity of the epoxy mixture for easier application on the surface.

How Long does an Epoxy Waterproofing Last?

Epoxy waterproofing is lasts between 10 to 15 years. The durability of the epoxy waterproofing depends on the epoxy product quality, surface preparation, application method, environmental condition, substrate compatibility, maintenance and intended use and traffic.

Is Epoxy Waterproofing Breathable?

Epoxy waterproofing is not breathable. Epoxy waterproofing is a dense and water-tight sealant that does not allow to pass water vapor to pass through. Hence, epoxy is highly recommended on concrete structures where complete water resistance is essential. Due to the zero-breathability epoxy waterproofing layer, moisture vapor does not escape through the layer. Hence, blistering can be observed inside the coating.

Is Epoxy Waterproofing Flexible?

Yes, the epoxy waterproof coating is limitedly flexible due to the inclusion of the epoxy flexiblizers. Due to its limited flexibility, it can withstand thermal fluctuations, small structural movements, and other physical forces.

Is Epoxy Waterproofing UV-Resistant?

Epoxy waterproofing that is formulated with UV-resistant additives or pigments is waterproof. But traditional epoxy is not UV resistant. If and only if the epoxy waterproofing is UV resistant can be used for outdoor usage because UV radiation can break down the chemical bonds in epoxy resin. It will cause loss of clarity, discoloration, and reduce the material’s performance. You can check the manufacturer’s product guide to ensure UV resistance before using it.

How to Apply Epoxy Waterproofing?

You can apply the epoxy waterproofing by following these 6 steps.

1. Prepare the surface: First, you should prepare the surface to be clean, dry, and free from any dust, dirt, oil, or grease. You should remove any existing paint or coatings on the surface. You can add a mild acid solution to bond better if the surface is concrete.
2. Apply the primer: Apply a suitable epoxy primer to the surface. This will help the epoxy coating adhere better and last longer.
3. Mix the epoxy: After the primer is completely dry, mix the epoxy in two parts: resin and hardener, before applying them to the surface. You should always follow the manufacturer’s instructions for the correct mixing ratio.
4. Applying on the surface: You can apply the epoxy mixture on the prepared surface using a roller or brush. The epoxy thickness should be between 2mm – 5mm.
5. Allow for curing: After the epoxy is applied to the surface, leave it for curing for about 24 hours. The curing time of the epoxy waterproofing is varies with the product and the environmental conditions.
6. Apply the second coating: You should apply the second coat If the manufacturer recommends it, or if you want a thicker coating. The second coating should be applied on the surface after the first one has fully cured.

Where Can You Use Epoxy Waterproofing?

Epoxy waterproofing can be used on the following materials and specific areas in the home.

Use of Epoxy Waterproofing on Materials

1. Concrete: Epoxy can be used on a concrete surface to prevent water penetration through the lower porosity layer.
2. Metal: Epoxy can be applied to the metal surface. Due to the zero breathability and water tightness of the epoxy coating, liquid water will not contact the metal surface, and it will protect prolong.
3. Wood: Epoxy waterproofing can be applied to the wood. It will fill the cracks and knots in the wood and making them waterproof and giving them a glossy and smooth finish.
4. Bricks: Epoxy waterproofing can be used to prevent water penetration through the higher porosity brick surface.
5. Stones: Epoxy waterproofing creates a water-impervious layer on the stone material after it is cured and dry. It will fill in cracks and gaps on the stone surface and give a smooth and glossy surface.

Use of Epoxy Waterproofing in the Home

Epoxy waterproofing can be used on bathroom, garage floor, fountains, swimming pools, terrace, and floors in house.

1. Bathroom: Epoxy waterproofing can be used on the bathroom floor and walls to protect from water. It can be used to fill any crack or damage on the surface. As well as epoxy waterproofing can be used on the tiled surface without removing it.
2. Garage floor: Epoxy waterproofing can be used successfully on the garage floor. Due to the higher water resistance and easy cleaning capability, it can remain free of oil, dust, and debris. As well as epoxy waterproofing has a higher abrasion resistance, which helps to less maintenance and prolong.
3. Fountain: Epoxy is an excellent waterproof solution for fountains because it prevents water seepage, surface erosion, hairline cracking, and material deterioration caused by continuous water exposure, UV radiation, and heat, while forming a durable, chemical-resistant, and rust-proof protective barrier on the fountain surface.
4. Swimming pools: Epoxy is an excellent waterproof solution for swimming pools because it prevents water absorption, leakage, chemical attack, and UV degradation while protecting concrete, plaster, and tile surfaces and improving slip resistance for pool safety.
5. Terrace: Epoxy is an excellent waterproof solution for terraces because it prevents rainwater penetration, surface cracking, and material degradation caused by sun and weather exposure, while forming a durable, UV-resistant, and long-lasting protective barrier over concrete, tile, and metal surfaces.
6. Floors: Epoxy is an excellent waterproof solution for floors because it forms an impenetrable moisture barrier that prevents concrete pore penetration, wood rot, and metal corrosion, while delivering high durability, chemical resistance, low maintenance, and long-term floor protection.

How to Protect Epoxy Waterproofing?

Epoxy waterproofing coating can be protected and improve effectiveness by following these 6 steps such as regular cleaning, avoiding heavy impacts on the surface, limiting exposure to sunlight, recoating when needed, avoiding harsh chemicals, and doing regular inspections and maintenance when needed.

1. Regularly cleaning the coating: Keep the surface clean from dirt, dust, and spills. You can use mild, non-abrasive cleaning agents and avoid harsh chemicals.
2. Avoid heavy Impact: Try to prevent dropping heavy objects on the surface that can cause cracks or chips in the epoxy coating.
3. Limit exposure to sunlight: In order to protect the epoxy waterproofing layer from UV rays, you can use a cover to limit the amount of direct sunlight on the epoxy surface.
4. Recoat when needed: Epoxy coating can wear and tear due to high foot traffic. You can apply a new coat of epoxy to maintain its waterproofing properties.
5. Avoid harsh chemicals: Epoxy coating should not be exposed to certain harsh chemicals that can degrade the coating.
6. Regular inspection: You should do regular inspections of the epoxy surface for any signs of damage, like cracks, chips, or discoloration.

How to Damage an Epoxy Waterproofing?

Epoxy waterproofing can be damaged due to these 6 reasons, such as physical impact, incorrect mixing or application, extreme temperature, prolonged chemical exposure, prolonged UV exposure, and abrasions occurring on the surface.

1. Physical Impact: Epoxy waterproofing coating can be damaged due to heavy impact from dropping heavy objects, or moving heavy equipment can cause cracks or chips in the epoxy coating.
2. Incorrect mixing and application: Epoxy waterproofing sealant can be damaged if the epoxy resin and hardener are not mixed in the correct proportions or if the surface is not properly prepared before application. The epoxy may not cure properly, leading to a weak or uneven coating that can easily be damaged.
3. Open to extreme temperatures: Epoxy waterproofing layer can be damaged due to open extreme heat or cold can cause it to expand or contract. This temperature fluctuation can cause to potentially lead to cracks.
4. Open to heavy chemicals: Epoxy waterproofing layer can be damaged due to exposure to too many chemicals for a long time. This can degrade the waterproofing layer over time.
5. Exposure to UV rays: Epoxy waterproofing layer can be damaged due to exposure to constant sunlight because sunlight consists of UV rays, which causes to decay the epoxy waterproofing layer to decay over time.
6. Abrasions: The Epoxy waterproofing layer can be damaged due to constant heavy foot traffic, or dragging heavy objects across the surface can wear down the epoxy over time.

EPOXY vs Bituminous Waterproofing: What are the Differences?

These are the material composition, performance, durability, and environmental resistance comparisons between EPOXY and Bituminous waterproofing

1. EPOXY waterproofing is a two-component mixture of epoxy resin and hardener, while bituminous waterproofing is a petroleum-based bitumen-derived membrane.
2. EPOXY waterproofing and bituminous waterproofing are both highly water resistant membranes.
3. EPOXY waterproofing membranes are not breathable, while bituminous waterproofing has a lower breathability
4. EPOXY waterproofing is not flexible, while bituminous waterproofing has a higher flexibility.
5. EPOXY waterproofing has an extremely high chemical resistance than bituminous waterproofing.
6. Standard EPOXY waterproofing has a higher UV resistance than bituminous waterproofing.

What is the Polyurethane Waterproofing?

Polyurethane waterproofing is a type of waterproofing method that uses a polyurethane membrane to protect surfaces from water damage. Polyurethane is a flexible, durable, UV-resistant, and weather-resistant waterproof material that can be used for building components waterproofing. Polyurethane waterproofing consists of two types: liquid membrane and sheet membrane.

1. Polyurethane liquid membrane – Polyurethane liquid is a thin, liquid-applied coating that cures to form a seamless, flexible, and durable waterproofing membrane. It can be applied to a variety of surfaces, including concrete, metal, and wood. Polyurethane waterproofing is often used for roofs, decks, and areas with many details or complex geometries due to its irregular shapes.
2. Polyurethane sheet membrane – A polyurethane sheet is a pre-formed sheet that is adhered to the surface to provide waterproofing. A polyurethane sheet membrane is used in below-grade applications such as basements and foundations, where there is a high risk of water ingress.

Is Polyurethane Waterproofing Better than Epoxy?

Epoxy waterproofing is known for its durability, resistance to chemicals, and ability to provide a high-gloss finish. It forms a hard, rigid surface that can withstand heavy foot traffic and is therefore often used in commercial and industrial settings. Epoxy is also a great choice for waterproofing basements, garages, and other concrete surfaces.

Polyurethane waterproofing is more flexible than epoxy, which allows it to accommodate movement and expansion in the substrate better. This makes it an excellent choice for areas that are prone to shifting and settling, such as roofs and decks. Polyurethane also has superior resistance to UV rays, making it a better choice for outdoor applications.

Is Cementitious Waterproofing Stronger than Epoxy?

No, cementitious waterproofing is not stronger than epoxy because cementitious waterproofing is less flexible and not resistant to chemicals; hence, it can be damaged due to external forces and chemicals easily. Therefore, it should not be used for higher foot traffic and chemical areas.