A vapor barrier installed in a wall before the insulation and drywall is added.

Sealing vapor barrier seams is an often overlooked step that can significantly impact the efficiency of the protection system and the long-term health of your crawl spaces

You must choose a high-performing tape to develop a strong barrier for minimal moisture intrusion and accumulation in the wall system. But the thing is, there are multiple tape options to choose from, which makes most homeowners confused. 

So, how do you know the best type of tape to use with vapor barriers? 

This article will go over the different options on the market to help you find the ideal solution for your crawl spaces.

What Is the Best Tape to Use For Vapor Barriers?

We recommend acrylic seam tape for sealing vapor barriers in your crawl spaces. It’s made from acrylic adhesive and a polyester film, making it strong and durable, providing a lasting seal that will protect your home from moisture damage.

Now that you have the quick answer, let’s discuss the benefits of using tape for vapor barriers.  

3 Benefits of Sealing Your Vapor Barriers With Tape

Enhanced Indoor Air Quality

A suitable sealing tape improves the air quality in your home by preventing moisture build-up and mold growth. If allowed to grow, mold infests the environment with allergens and irritants, resulting in allergies, breathing problems, and inflammation in some people. 

With your vapor barriers sealed with tape, you can rest assured that you and your family will breathe fresh and healthy air.  

Improved Energy Efficiency 

The tape seals out unwanted moisture when properly applied, which improves the vapor barrier’s effectiveness and contributes to a sustainable home. In addition, it works wonders to minimize energy loss and heat transference through floors, walls, and ceilings, reducing energy bills.    

Extended Property Lifespan

The ideal vapor barrier tape will improve the durability and longevity of your property by keeping structurally damaging mold at bay. 

However, keep in mind that the tape may degrade and lose its adhesive properties over time and expose some points in the seal, compromising the integrity of your home. You can remove the damaged tape and replace it with a new one in time to avoid this issue.   

A serviceman installs a vapor barrier on the ceiling in a basement
A serviceman staples a vapor barrier on a basement ceiling, the first step before applied seam tape

Asphalt vs. Rubber vs. Acrylic Seam Tape For Vapor Barriers

Construction seam tape manufacturers understand the growing demands of homeowners and strive to introduce better products to promote a structure’s energy efficiency and service life. In addition, they want to ensure the products are durable and capable enough to work in different temperatures and climate conditions. 

Asphalt, rubber, and acrylic tapes are the top options for construction seam taping—the vapor barrier installation team you hire will likely tell you the same. 

Let’s discuss the pros and cons of each in detail to identify the best type of tape to use with vapor barriers. 

Asphalt Seam Tape

Vapor barrier installation professionals and builders have used asphalt seam tape for years, thanks to its low cost. It comes from modified bitumen (similar to the asphalt found in eaves flashing).  

However, remodeling workers eventually discovered that this tape had several drawbacks. For starters, it degrades quickly, leading to premature breakdown of properties. Although it’s great that it is less expensive, the quality of work it delivers makes it a less ideal choice for sealing vapor barriers. 

Other cons of asphalt construction seam tape include: 

  • Requires priming to securely bond with substrate materials, such as concrete and oriented strand board (OSB)
  • Mess during installation
  • A loss of durability when exposed to UV rays
  • A loss of adhesive power at 50ºF, whereas its bonding capabilities deteriorate at 40ºF, proving a poor choice for projects in cold weather
  • It softens at 185ºF and 210ºF if not specifically formulated for hot weather
  • Emitting volatile organic compounds (VOCs) that are harmful to health

Rubber Seam Tape

Rubber or butyl construction seam tape used today comes from a synthetic rubber that helps create an airtight product. The design and formulation of this tape aimed to provide an improved outcome from asphalt tape—and it succeeded to a great extent.  

A roll of black rubber seam tape
Courtesy of Rubber Roofing Direct

Here’s how rubber seam tape is better than asphalt tape:

  • It simply requires you to peel it off and adjust it according to your installation needs, ensuring a cleaner application. 
  • More flexible and stable than asphalt tape and performs much better in hot and cold climates—you can apply it in temperatures ranging from -40° F to 120° F and service it in temperatures from -40° F to 200° F without worries.
  • It forms stronger bonds with difficult substrates like concrete.

Nevertheless, some builders complain that rubber seam tape has the following drawbacks, including:

  • Releasing harmful VOCs
  • The tendency to dry out, discolor and become less adhesive when exposed to UV rays
  • It doesn’t work properly if installed below 40°F on a surface with moisture or contaminants

Acrylic Seam Tape

This tape outperforms both asphalt and rubber construction seam tapes, allowing you to ensure a fully-sealed, energy-efficient structure. As a result, the vapor barriers in your crawl spaces become extra durable, and your indoor air quality improves significantly. 

Two rolls of acrylic seam tape partially unrolled, side-by-side
Courtesy of AliExpress

Here’s how acrylic seam tape is better than asphalt and rubber tapes:

  • Excellent adhesive properties, which only get stronger with time
  • Doesn’t degrade upon exposure to UV rays, oxidation, or even harsh chemicals
  • Doesn’t pollute the environment with off-gases
  • Withstands extreme weather conditions, performing well in temperatures ranging from -30°F to 300°F without losing its adhesive capabilities
  • Can be used inside and outside a structure

The best thing about acrylic seam tape is that it provides an airtight envelope for vapor barriers to minimize moisture intrusion and energy loss. Moreover, it prevents mold growth, ensuring a longer lifespan for your home.  

That said, builders believe acrylic seam tape is worth the small extra expense over asphalt and rubber tapes—and you should too.

Frequently Asked Questions: Does Duct Tape Work on Vapor Barriers?  

No, duct tape is too porous to work on vapor barriers.

A homeowner applies duct tape to a seam on a radiant barrier beneath a ceiling
Courtesy of HVAC SEER

Also, please note that duct tape will rip the polyurethane off the floor if you have hardwood floors, so it’s better to not even try. 

Factors to Consider When Picking Vapor Barrier Tape

Although we’ve explained why acrylic seam tape is the best option for sealing vapor barriers, choosing the perfect product may overwhelm you, considering the wide range of options available. 

Below are a few things you should consider when choosing the best vapor barrier tape. 

Ease of Application 

Look for a tape with marked edges—it’ll be easier to tear and quicker to apply. Also, ensure it’s flexible to allow workers to seal openings quickly in tight corners. The convenient application will save time and frustration, ensuring your project is finished efficiently. 


Adhesion is critical when choosing a vapor barrier tape. You must go for one that’s not too sticky to work with, but it should maintain adhesion in hot, cold, and wet environments. 


The tape should have excellent resistance to moisture and UV rays. It shouldn’t get brittle or degrade when exposed to certain environmental factors. Otherwise, your vapor barriers won’t remain adequately sealed for long. 


The ideal tape for your vapor barriers will have a considerable tensile strength to stay flat and maintain its form over time so that it doesn’t compromise the structure’s integrity.  

The Best Vapor Barrier Tape for Long-Term Integrity and Energy Efficiency

After thorough research and analysis, we’ve determined acrylic seam tape is an excellent choice for anyone who wants a quick and straightforward solution. It’s easy to use, and doesn’t make a mess during the application, either, so you don’t have to worry about compromising your property’s aesthetics. 

The tight seal provided by this tape will prevent moisture from seeping through your crawl spaces. The best thing is that it’s highly resistant to moisture and humidity and can withstand extreme temperatures without cracking or peeling, being perfect for use in damp and dry environments. 

Discuss the unique conditions and requirements of the vapor barriers in your crawl spaces with experts before picking an acrylic seam vapor barrier tape. The options are endless, so you must do your research to avoid wasting your time or money on the wrong product. 

Best of luck!

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