Is Elastomeric Paint a Vapor Barrier: Everything You Need to Know

We have all heard of paint being used to make our walls and ceilings look great, but what about using it as a vapor barrier? Is elastomeric paint a vapor barrier? The answer to that question is not a straightforward one, and so in this article, we will explore this topic in detail.

Elastomeric paint is a type of paint that is commonly used in regions with extreme weather conditions such as heavy rains or high humidity. This type of paint is known for its ability to stretch and cover cracks, which helps to keep moisture from seeping in. However, does that mean that elastomeric paint is a vapor barrier? Let’s find out more.

When it comes to using elastomeric paint as vapor barriers, there are various factors to consider. Although elastomeric products have waterproofing properties, they do not prevent moisture from passing through the surface. So, while elastomeric paint may provide a barrier against rain or snow, it cannot be used as a vapor barrier on its own. Understanding this difference is essential for homeowners and construction professionals alike as it helps them make informed decisions about the best products to use for their particular situations.

Examples of Vapor Barriers

A vapor barrier is a material that prevents the flow of moisture through walls, floors, and ceilings. By stopping moisture transfer, vapor barriers can reduce the risk of moisture-related problems such as mold growth and structural decay. Some common materials used as vapor barriers include plastic sheeting, foil-backed drywall, and spray foam insulation. Let’s take a closer look at some examples of vapor barriers.

  • Plastic sheeting: Plastic sheeting is a popular choice for vapor barriers because it is affordable and easy to install. Typically made of polyethylene or polypropylene, plastic sheeting comes in various thicknesses and can be used in walls, floors, and ceilings. It is also widely available at most hardware stores and home improvement centers.
  • Foil-backed drywall: Foil-backed drywall is another common vapor barrier material. It is essentially regular drywall with a foil backing that acts as a vapor barrier. Foil-backed drywall is typically used in basement walls and ceilings, as well as in bathroom and kitchen walls.
  • Spray foam insulation: Spray foam insulation is a synthetic material that can be sprayed onto walls, floors, and ceilings. It creates an airtight seal that prevents moisture from passing through. Spray foam insulation is more expensive than other vapor barrier options but can provide superior insulation and moisture protection.

Composition of Elastomeric Paint

Elastomeric paint is a type of paint that contains high amounts of elastic polymers, making it highly flexible and durable. The main components of elastomeric paint are:

  • Resins: These are natural or synthetic substances that act as the binder for the paint, holding all the other components together. In elastomeric paint, the resins used are usually acrylic, silicone, or polyurethane.
  • Pigments: These are substances that give color to the paint. In elastomeric paint, pigments can be either organic or inorganic.
  • Fillers: These are particles added to the paint to improve the opacity and texture of the final product. In elastomeric paint, the most common fillers are calcium carbonate, talc, and silica.
  • Additives: These are chemicals added to the paint to improve its properties, such as its adhesion, water resistance, and UV protection. In elastomeric paint, common additives include wetting agents, biocides, and thickeners.

When combined, these components create a paint that is highly flexible and can stretch up to 600% of its original length. This unique composition makes elastomeric paint an ideal choice for surfaces that are prone to cracking or movement, such as stucco, concrete, and masonry. It also provides a waterproofing layer that can help prevent water damage and mold growth.

Elastomeric Paint as a Vapor Barrier

While elastomeric paint is not designed specifically to be a vapor barrier, it can have some vapor barrier properties. The paint’s high elasticity and water-resistant properties can help prevent moisture from penetrating through the paint and into the substrate underneath. This can be especially helpful in areas with high humidity or where moisture is known to be a problem.

PropertyElastomeric Paint
ElongationUp to 600%
Water resistanceExcellent

However, it is important to note that elastomeric paint is not a substitute for a true vapor barrier. If a vapor barrier is required for the building’s design, additional measures may need to be taken such as installing a separate vapor barrier membrane.

In conclusion, elastomeric paint is a highly flexible and durable coating that is composed of resins, pigments, fillers, and additives. While it does have some vapor barrier properties due to its water resistance and elasticity, it is not a replacement for a true vapor barrier when one is required for a building’s design.

How Elastomeric Paint Works

Elastomeric paint is a popular choice for homeowners and commercial buildings because it can significantly enhance the durability and longevity of a building’s walls. This type of paint is highly elastic and able to expand and contract with temperature and moisture change, making it particularly effective in areas with fluctuating weather patterns.

Elastomeric paint contains high-quality resins that serve as a vapor barrier, preventing water and moisture from penetrating through the walls and potentially causing damage such as mold growth, water stains, and peeling paint. The paint also has a high solid content, which allows it to fill in small cracks and gaps on the surface, further protecting the walls from moisture infiltration.

Here are some key ways that elastomeric paint works:

  • Water Resistance: Elastomeric paint is designed to repel water, ensuring that it does not seep into the walls and damage the building’s structure. It is especially useful in areas prone to heavy rain and high humidity.
  • Flexibility: As mentioned earlier, elastomeric paint is highly elastic and can stretch and contract with changing temperatures and humidity levels. This means that the paint can maintain its integrity over time, even in areas with extreme weather fluctuations.
  • Durability: Elastomeric paint is known for its durability and ability to resist wear and tear. It can also protect against other types of damage, such as fading, cracking, and peeling.

In addition to its protective properties, elastomeric paint can also help lower cooling costs during hot summer months. Because it reflects a significant amount of sunlight, it can keep the interior of a building cooler, reducing the need for air conditioning.

If you’re considering using elastomeric paint on your building, it’s important to choose a high-quality product and have it professionally applied. A qualified contractor can ensure proper surface preparation and paint application, resulting in the best possible outcome for your walls.

Overall, elastomeric paint is an excellent choice for anyone looking to improve the longevity, durability, and aesthetic appeal of their building’s walls. Its unique properties make it a popular choice in both residential and commercial applications, particularly in areas with harsh weather conditions.

Advantages and Disadvantages of Elastomeric Paint

As with any product, there are both advantages and disadvantages of using elastomeric paint as a vapor barrier. Below, we will explore each in detail.


  • Flexibility: Elastomeric paint is comprised of an elastic polymer that allows it to stretch up to 600% of its size without breaking, making it an ideal choice for exterior surfaces that will expand and contract with changes in temperature and humidity.
  • Durability: Elastomeric paint is resistant to cracking, peeling, and fading, which makes it a cost-effective choice since it has a longer lifespan than traditional paints.
  • Moisture Barrier: Elastomeric paint provides a good barrier against moisture, which makes it an excellent choice for homes in humid environments or areas experiencing frequent rainfall.
  • Energy Efficient: Elastomeric paint has insulating properties that help reduce heat transfer which ultimately reduces air conditioning costs, making it an energy-efficient option.


Elastomeric paint, like anything, has a few drawbacks that users should be aware of before deciding on this as their main coating for sealing their house.

  • Cost: Elastomeric paint can be more expensive than other types of exterior paint, and its use requires specific applicator equipment, which can be an additional expense.
  • Thickness: While elastomeric paint can help fill small cracks, excessive layering can create an unattractive finish and a thick buildup, which can require additional maintenance or removal.
  • Application: Proper application of elastomeric paint is key to its success, and it requires a certain level of knowledge and equipment to achieve a smooth, seamless finish. Incorrect application can lead to bubbling and cracking of the coating.

Elastomeric Paint as a Vapor Barrier

While elastomeric paint is an exceptional choice for sealing surfaces and preventing moisture penetration, it should not be solely relied upon as a vapor barrier. Although it can help to minimize the amount of moisture that passes through surfaces, it is not a substitute for a proper vapor barrier installation using one of the appropriate materials such as polyethylene, foil-faced plastic, or kraft paper.

MaterialPerm rating (after 2 months)
Foil-faced Plastic0.02
Kraft Paper0.10

As seen in the table above, elastomeric paint has a perm rating of approximately 15, which is higher than that of proper vapor barrier materials. Therefore, relying on elastomeric paint to function as a vapor barrier may lead to moisture issues within the home’s structure and should not be relied upon as the sole method of moisture control.

Comparison of Elastomeric Paint to Other Vapor Barriers

Elastomeric paint is a popular choice for homeowners who want to protect their walls from moisture and other environmental factors. But how does it stack up against other types of vapor barriers? Let’s take a closer look.

  • Plastic Sheeting: One common type of vapor barrier is plastic sheeting. This material is inexpensive and easy to install, but it can tear easily and may not be as durable as other options.
  • Metal Foil: Another option is metal foil, which can provide excellent insulation and protection from moisture. However, it can be difficult to install and may not be as flexible as elastomeric paint.
  • Spray Foam Insulation: Spray foam insulation is another popular choice for vapor barriers. It can provide excellent insulation and protection against moisture, but it can be expensive and may require professional installation.

When compared to these other options, elastomeric paint has several advantages. For one, it is relatively easy to apply, even for homeowners with little experience in painting. Additionally, it is flexible, which means that it can expand and contract with changes in temperature and humidity without cracking or peeling.

In terms of durability, elastomeric paint is also a good option. It can provide long-lasting protection against elements like moisture, sunlight, and wind. And because it is a paint, it can also offer aesthetic benefits, such as improving the appearance of your walls.

Plastic SheetingInexpensive, easy to installTears easily, may not be as durable
Metal FoilExcellent insulation and protection from moistureDifficult to install, may not be as flexible
Spray Foam InsulationExcellent insulation and protection against moistureExpensive, may require professional installation
Elastomeric PaintEasy to apply, flexible, durable, aesthetic benefitsMay require multiple coats, can be expensive

Of course, there are also some potential downsides to using elastomeric paint. For one, it can be more expensive than other vapor barrier options, especially if you need to apply multiple coats. Additionally, it may not be as effective in extreme temperatures or climates.

Ultimately, the choice of vapor barrier will depend on a variety of factors, including your budget, your climate, and the specific needs of your home. However, if you are looking for a versatile and durable option that offers both protection and aesthetic benefits, elastomeric paint is certainly worth considering.

Proper Application of Elastomeric Paint as a Vapor Barrier

Elastomeric paint can be a great option for creating a vapor barrier on a variety of surfaces, including metal roofs, masonry walls, and concrete foundations. However, like any painting task, it requires proper preparation, application techniques, and maintenance to ensure its effectiveness.

  • Surface preparation: Before applying elastomeric paint, the surface must be thoroughly cleaned and dried to remove dirt, debris, and any other contaminants that could interfere with adhesion. Use a pressure washer or scrub brush to clean the surface and allow plenty of time for it to dry completely.
  • Priming: For optimal adhesion and sealing, apply a high-quality primer designed for elastomeric coatings. This will also help to prevent any underlying stains or discoloration from bleeding through the topcoat.
  • Application technique: Elastomeric paints can be applied using a brush, a roller, or a sprayer, depending on the surface and the desired finish. Be sure to follow the manufacturer’s instructions for mixing, dilution, and application rates. Apply the paint in thin, even coats, taking care to avoid drips or puddles.
  • Drying time: Allow ample drying time between coats, typically 24-48 hours, depending on the humidity and temperature. If additional coats are needed to achieve the desired thickness, be sure to apply them in the same manner as the first coat.
  • Maintenance: Once the elastomeric coating is fully cured, it will provide a durable, waterproof surface that can last for many years. However, regular inspections and maintenance are important to ensure its ongoing effectiveness. Check for any signs of cracking, splitting, or peeling, and make repairs as needed.
  • Professional installation: For larger or more complex surfaces, it may be wise to enlist the help of a professional contractor who has experience with elastomeric coatings and can ensure proper application and maintenance.

In conclusion, when applied properly, elastomeric paint can be an effective and long-lasting vapor barrier solution for a variety of surfaces. By following the proper preparation, application, and maintenance techniques, you can create a seamless, waterproof surface that will protect your property for years to come.

Maintenance of Elastomeric Paint as a Vapor Barrier

Ensuring the proper maintenance of elastomeric paint as a vapor barrier is essential to its longevity and effectiveness. Here are some tips to follow:

  • Regular inspections: It is recommended to inspect your elastomeric paint coating twice a year, preferably in the spring and fall. Look for any signs of wear and tear, cracks, or peeling, as these could indicate moisture damage.
  • Clean surface: It is crucial to keep the surface of your elastomeric coating clean. Dirt, debris, and other materials can accumulate over time, allowing moisture to seep through and causing damage to your coatings. Use a gentle detergent and water to clean your elastomeric coating when needed.
  • Repair damages: If you notice any damage to your elastomeric coating, it’s essential to act quickly. Failure to do so can lead to moisture infiltration, which can cause significant damage to your building. Repair any damages promptly to maintain the integrity of your coating.

Along with these tips, it’s also important to consider the application of your elastomeric coating. It’s best to consult with a professional to determine the proper application method for your specific building and needs. The application method and thickness of the coating can affect the effectiveness of the vapor barrier.

Below is a table summarizing the main maintenance advice for elastomeric paint as a vapor barrier.

InspectTwice a year (spring and fall)
CleanWhen needed
Repair damagesAs soon as possible

By following these essential tips and considering proper application methods, you can ensure that your elastomeric coating provides the durability and protection you need for your building. A well-maintained elastomeric coating can function as an effective vapor barrier, guarding against moisture intrusion and protecting your building from damage and costly repairs in the long run.

Is Elastomeric Paint a Vapor Barrier – FAQs

1) Is elastomeric paint waterproof?

Elastomeric paint has waterproofing properties that make it effective in preventing water from penetrating through the surface. However, it is not entirely waterproof and may not be suitable for underwater and consistently wet surfaces.

2) Can elastomeric paint be used as a vapor barrier?

Yes, elastomeric paint can act as a vapor barrier by preventing moisture from escaping or entering through the substrate. Its flexible properties make it an ideal candidate for surfaces, such as masonry, stucco, and concrete.

3) What are the benefits of using elastomeric paint as a vapor barrier?

Elastomeric paint offers numerous benefits as a vapor barrier, including energy savings, mold and mildew prevention, and protection against structural damage caused by moisture.

4) Is elastomeric paint reliable in humid conditions?

Elastomeric paint is reliable in humid conditions, as it can resist high humidity levels and reduce or prevent water vapor transmission. Its ability to expand and contract also makes it a suitable choice for use in areas where temperature fluctuations occur.

5) Can I apply elastomeric paint on my own?

While it is possible to apply elastomeric paint on your own, it is recommended that you hire a professional. Professional contractors have the necessary expertise and equipment to prepare and apply the paint correctly, ensuring better results.

6) How long will elastomeric paint last when used as a vapor barrier?

The lifespan of elastomeric paint as a vapor barrier depends on several factors, such as weather conditions, surface preparation, and quality of the paint. However, it can last up to 10 years or more with proper maintenance.

7) Is elastomeric paint cost-effective as a vapor barrier?

Although elastomeric paint may be more expensive than other types of paint, it is cost-effective in the long run due to its ability to prevent structural damage caused by moisture. Additionally, it can provide energy savings and reduce HVAC costs.

Closing Paragraph – Thanks for Reading!

Thank you for joining us in exploring whether elastomeric paint is a vapor barrier. We hope this article has helped answer any questions you may have had. If you need more information or have additional questions, please feel free to visit us again. We look forward to seeing you soon!