What to Know About Polyurethane Waterproofing?

Written By Adam Paul - Waterproofing Expert

Polyurethane (PU) is a waterproof material. Waterproof polyurethane has excellent mechanical, chemical, thermal, UV, and weather-resistant properties. As well as PU forms a uniform, elastic, vapor-permeable sealing layer on the surface. Therefore, PU is used in a wide range of waterproofing projects in buildings and constructions. 

Water-based polyurethane is also waterproof, although it is mixed with water. Modified polyurethane is a type of polyurethane that has been chemically altered to provide specific properties. Polyurethane waterproofing membrane should follow the ASTM standards. Before you choose the waterproofing polyurethane, you should be aware of the ASTM test methods of the product.

The most used waterproof polyurethane products are resin, sealant, flooring, caulk, and liquid membrane. Among them, polyurethane liquid waterproofing is the most used membrane for building and construction. Polyurethane waterproofing can be applied on roofs, terraces, bathrooms, kitchens, basements, bridges, tunnels, parking decks, balconies and patios, foundations, and walls. You can apply the PU waterproofing on the surface as liquid, injection grouting, coating, sealant, foam, PU-bitumen, and PU-cementitious membrane. All of these membranes are modified in order to improve the properties of the Polyurethane. 

Using polyurethane as a waterproofing membrane has both advantages and disadvantages. As advantage, PU is highly flexible, durable, with no seams, versatile, and easy to apply on the surface. The disadvantages of PU are high sensitivity to moisture, expensive coating, and need skill to apply on the surface.

A PU coating can be damaged due to human effects and enviromental effects. Polyurethane and urethane are two types of materials with different properties. Epoxy can be used as an option for polyurethane. But you should know the differences between them.

Is Polyurethane Waterproof?

Yes, polyurethane (PU) is a waterproof material. It consists of a polymer that is made up of chains of organic units joined by carbamate links. This carbamate line composition creates a closed-cell structure that completely blocks water, making it an excellent material for waterproofing. Due to water waterproof capability of polyurethane, it can be used as a waterproofing membrane for buildings and constructions. 

Polyurethane waterproofing is a liquid type of waterproofing. It can be applied on the surface as a layer or injected into the materials. Waterproof polyurethane has excellent mechanical, chemical, thermal, UV, and weather resistance properties. As well as PU forms a uniform, elastic, vapour-permeable sealing layer on the surface. Therefore, PU is used in a wide range of waterproofing projects in buildings and constructions.

You can read in depth detail guide about Is Polyurethane Waterproof. It includes all the details about water based polyurethane, oil based polyurethane, thermoplastic polyurethane (TPU) and thermosetting polyurethane.

Is Waterbase Polyurethane Waterproof?

Water-based polyurethane is a waterproof membrane although it is mixed with water to apply on the wood floorings instead of the oil. Water-based polyurethane creates a more clear and less glossy finish compared to oil-based polyurethane. Water-based polyurethane also dries faster, has less odor, and is less toxic but may require more coats. It is less durable than oil-based polyurethane. 

What is Modified Polyurethane?

Modified polyurethane is a type of polyurethane that has been chemically altered to provide specific properties in order to improve the resistant to heat, UV light, oxidation, and other environmental factors. PU modification can change the softness, hardness, flexibility, and rigidness of the PU. As a result of this, PU can be used as a water protection barrier for various industries such as construction, automotive, and furniture.

More than that these 6 Types of Polyurethane Types are highly prone to water and Aqviz highly recommends as waterproofing membranes.

What are the Tests and ASTM Standards for Polyurethane Waterproofing?

Polyurethane waterproofing should be tested according to the international standards. ASTM is the most used testing standard for the materials. Therefore PU waterproofing membrane that you use should be tested according to the ASTM standards. Below are the test and ASTM standards for the Polyurethane waterproofing.

What are the 5 Types of Waterproof Polyurethane Products?

These are the 5 types of waterproof polyurethane products.

1. Waterproof polyurethane resin
2. Waterproof polyurethane sealant
3. Waterproof polyurethane flooring
4. Waterproof polyurethane caulk
5. Polyurethane liquid membranes

Waterproof Polyurethane Resin

Waterproof polyurethane resin is a type of synthetic resin that is highly resistant to water. Waterproof PU has excellent adhesion, flexibility, durability, UV resistance, and abrasion resistance material. Hence, it can bond strongly to various materials, including concrete, metal, and wood. It can withstand physical wear and tear, making a long-lasting waterproofing solution. Waterproof PU resin is mostly used in roofs, walls, and floors, sealing cracks and joints and providing a protective coating for outdoor furniture and equipment.

Waterproof Polyurethane Sealant

Waterproof polyurethane sealant is a type of sealant that is commonly used in construction and other industries to prevent water and moisture penetration. Waterproof polyurethane sealant is a liquid-form material that can be used to seal cracks and joints in the waterproof membranes on roofs and walls. It is mainly used to prevent water leakage through the seams and joints. 

Polyurethane sealant is resistant to weathering, ageing, and UV radiation. It can bond to variety of construction materials, such as concrete, wood, metal, and plastic. 

Waterproof Polyurethane Floorings

Waterproof polyurethane flooring is a type of floor finish that is highly resistant to water damage. PU floorings are highly resistant to water, moisture, scratches, stains, and water damage. Hence, it can be used in commercial settings with high-traffic zones, such as kitchens, bathrooms, and hospitals, but it can also be a practical choice for residential homes.

Polyurethane flooring can be applied as a matte, semi-gloss, or high-gloss finish, and it can be used over a variety of substrates, including concrete, wood, and tile. This makes it a versatile choice that can complement a range of interior design styles.

Waterproof Polyurethane Caulk

Waterproof polyurethane caulk is a type of sealant that is used to fill gaps and cracks in various types of surfaces that are subjected to watering. Waterproof PU caulk is used in various applications, including sealing joints and cracks in concrete, filling gaps around windows and doors, and sealing areas where different types of building materials meet. It is also used in places where a waterproof seal is needed, such as in bathrooms, kitchens, and exterior applications.

Polyurethane caulk adheres well to many different types of materials, including wood, concrete, brick, glass, metal, and most types of plastic. It is flexible, allowing it to expand and contract with the materials it's bonded to, which helps prevent cracking and peeling.

Polyurethane Liquid Membrane

Polyurethane liquid membrane is a type of waterproofing solution that is applied as a liquid and then cures to form a seamless, flexible, and durable membrane on the surface. It is commonly used in various construction projects to protect surfaces from water damage and leaks.

The advantages of polyurethane liquid membranes are numerous.

1. Provides excellent waterproofing properties - PU can be used for heavy rainfall or high moisture levels. 
2. Excellent Flexibility - The flexibility of the membrane allows it to accommodate structural movements and temperature changes without cracking or breaking, ensuring long-lasting performance. 
3. Excellent adhesion - PU has excellent adhesion to a wide range of substrates, including concrete, metal, and wood, making it suitable for various applications. It also 
4. Excellent resistance to UV radiation, chemicals, and abrasion - hence it is highly durable and suitable for both interior and exterior use. 
5. Easy and efficient installation - PU installation can reduce labor time and costs. 

Due to these advantages, liquid PU membrane can be applied in various thicknesses, depending on the specific requirements of the project, such as slabs, balconies, basements, swimming pools, and balconies and bathrooms.

What are the Applications of Polyurethane Waterproofing?

Polyurethane and its formations can be applied in both building and construction fields to protect the surfaces from the water. These are the major applications of PU waterproofing membranes.

1. Polyurethane for roofs and terraces - Polyurethane waterproofing can be used for roof waterproofing and terrace waterproofing due to its excellent resistance to water, UV rays, and weather. PU coating is durable and seamless that can cover the surface without any joints.
2. Polyurethane for bathrooms and kitchens - PU can be used for both bathrooms and kitchens. Polyurethane waterproofing can be used for bathroom floors, walls and shower walls from water splashing. 
3. Polyurethane for basements - Polyurethane waterproofing creates a barrier that prevents water from seeping into the basement. PU can be used for basement waterproofing as liquid and injection methods.
4. Polyurethane for bridges and tunnels - Polyurethane waterproofing is used in the construction of bridges and tunnels to protect them from water damage and corrosion.
5. Polyurethane for water tanks - Polyurethane waterproofing is applied to the interior of water tanks to prevent leaks and preserve the quality of the water.
6. Polyurethane for parking decks - Polyurethane waterproofing is used on parking decks to protect them from weather-related damage and to ensure their longevity.
7. Polyurethane for balconies and patios - Polyurethane waterproofing helps to protect balcony and patio surfaces from water damage and extends their lifespan.
8. Polyurethane for industrial floors - and need to resist chemical spills. Polyurethane waterproofing helps to protect industrial floors that often endure heavy traffic open to chemicals. PU waterproofing, making them more durable and resistant to wear and tear.
9. Polyurethane for swimming pools - Polyurethane waterproofing is used for swimming pool waterproofing, ensuring they remain safe and functional.
10. Polyurethane for foundation walls - Foundation walls are used to prevent water infiltration and protect the structural integrity of a building. Polyurethane waterproofing is often applied to foundation walls by injection.
11. Polyurethane for ship decks - To protect from harsh weather conditions and constant exposure to water, polyurethane waterproofing is used on ship decks. 

Read More How to Apply Polyurethane on Concrete.

What are the Application Types of Polyurethane Waterproofing?

Polyurethane waterproofing can be applied as liquid polyurethane, injection PU, PU coating, Pu selant, PU foam, PU bitumen membrane and cementitious polyurethane waterproofing. These application type of the PU help to increase the durability and performance of the PU layer. Each of these application types should be applied as below.

1. Apply liquid polyurethane - Liquid-applied polyurethane can be applied on roofs, balconies, and terraces. The liquid is applied using a roller or brush, creating a seamless, highly elastic, and durable waterproofing membrane.
2. Apply polyurethane injection grouting - Injection PU can be used for sealing cracks in concrete structures, leaking foundations, and leaking slabs. The crack injection can be done while water is leaking. After the PU spreads over the leaking space, that will be hardened and form a solid non, non-dissolved foam. 
3. Apply polyurethane coating - PU coating is used for waterproofing a variety of surfaces, including concrete, wood, and metal. The coating is applied using a brush, roller, or spray and forms a tough, flexible, and waterproof layer.
4. Apply polyurethane sealant - Polyurethane sealant can be used for sealing joints and gaps in a variety of structures, including buildings, bridges, and tunnels. The sealant is applied using a caulking gun and forms a flexible, waterproof seal.
5. Apply polyurethane foam - PU foam is sprayed into place and then expands to fill gaps, making it an effective water and air barrier. It's often used in roofing applications or to insulate large areas like walls or ceilings.
6. Apply PU bitumen membrane - PU bitumen membrane is a hybrid system that combines the flexibility and elasticity of polyurethane with the durability of bitumen. It's often used for waterproofing roofs, foundations, and underground structures. 
7. Apply Cementitious PU membrane - Cementitious PU membranes combine cement and polyurethane to create a highly durable and resistant waterproofing solution. It's often used in areas with high levels of humidity or water exposure. This can be applied on the surface using a trowel or brush.

What are the Advantages and Disadvantages of Polyurethane Waterproofing?

The advantages and disadvantages of polyurethane waterproofing are highly important when selecting a waterproofing membrane for buildings and constructions. Polyurethane has various advantages and disadvantages due to its physical and chemical properties. These are the common advantages and disadvantages of PU as a waterproofing membrane.

Advantages of PU waterproofing

1. High flexibility - PU waterproofing has high flexibility.
2. High durability - PU waterproofing is highly resistant to UV radiation and weathering. Hence it is durable.
3. No-seams - After applying PU coating, it forms a seamless layer. It can reduce the leakage between joints.
4. Easy to apply - PU can be applied on the surface using a spray, roller, or using a brush.
5. Versatility - PU can be used on a variety of surfaces, including concrete, wood, and metal.

Disadvantages of PU waterproofing

1. Expensive membrane - PU is more expensive than other types of waterproofing membranes due to its wide range of usage
2. Sensitive to moisture - The PU layer can be blistering if the layer is not properly adhered to the substrate.
3. Need a skill to apply - You should have a certain level of skill and experience to ensure a proper and effective application. Improper application can lead to failures in the waterproofing system.

How to Damage a Polyurethane Waterproofing Membrane?

A waterproof polyurethane membrane can be damaged due to environmental effects, and human effects. A polyurethane waterproofing membrane can be damaged as follows. 

6 Damaging Ways of Polyurethane Waterproofing.

1. Physical damage on the PU layer, such as heavy punctures.
2. Incorrect polyurethane waterproofing installation
3. Wrong PU membrane choosing
4. Not following the manufacturing guidelines
5. Expose the PU layer to harsh chemicals
6. Extrem temperature in the environment
7. Exposure of the PU layer to UV rays
8. Poor maintenance of the polyurethane coating

Due to these damages, water can leak into the substrate. It can cause mold and mildew growth, wall dampness, paint peeling, material deterioration, and decay of the structure.

If the Polyurethane waterproof membrane is damaged, you should choose another type of waterproofing membrane instead of polyurethane.

What are the Differences Between Polyurethane and Urethane?

Urethane and polyurethane are different terms and refer to different things. 

Polyurethane is a type of polymer that is made by reacting a polyol with a diisocyanate. It's a versatile material that can be made with a wide range of properties. The properties of the PU depend on the specific chemicals and processes used. PU is mostly used for waterproofing membranes, paints, adhesives, mattresses, and adhesives.

Urethane can be identified as ethyl carbamate technically. It is a substance that was used in the production of a wide range of items in the past, from medicines to pesticides. However, due to safety concerns, its use has been largely phased out in many countries. 

What are the Differences Between Polyurethane and Epoxy?

Polyurethane and epoxy are both waterproofing membranes. But there are extraordinary differences. These differences affect the performance and durability of the waterproofing layer. Epoxy crack injection is the same as the PU injection. But PU is better than epoxy injecting.

7 Main differences between polyurethane and epoxy

1. Polyurethane is more flexible than epoxy. 
2. Polyurethane is more resistant than epoxy
3. Polyurethane can withstand up to -30 degrees Celsius 
4. Polyurethane has better behaviour in acidic conditions
5. PU is more sensitive to moisture than epoxy.
6. Polyurethane has less curing time than epoxy
7. Epoxy is harder than polyurethane

Before you apply epoxy as a waterproofing membrane, you should know about epoxy waterproofing and its usage.