A worker measuring a roll of vapor barrier in preparation to cut it

Vapor barriers can be significant and sometimes necessary additions to your house. These barriers can prevent moisture from concentrating in your walls and causing damage to their structure. 

However, there are additional benefits that they can provide if installed.

If you want to know more about the advantages of vapor barriers and if they increase efficiency, read on. You’ll also find information on what exactly these insulators are, their benefits, how they should be installed, and more.

And if you’re looking for a calculator to see what installing a vapor barrier might cost you, try out our Vapor Barrier Cost Calculator here.

Does a Vapor Barrier Help With Efficiency?

Vapor barriers can increase efficiency and lower your energy bills. Moisture inside the walls can cause your house to retain or release heat poorly. By diffusing the moisture, a vapor barrier keeps your home warmer during the colder months and more relaxed during heat, thus lowering your energy bill.

Why Is a Vapor Barrier More Efficient?

Humidity is a major risk to your home. It creeps into the foundations of your house and seeps through your walls. 

One of the main consequences of this excess moisture is that it affects the temperature of the air inside your home. Humid air can be too stuffy during hot days and too chilly during colder periods, affecting the temperature inside your house.

If you have excess moisture in your home, you will have to deal with these temperature issues. You’ll have to keep the air conditioning on all year long to stay cool during the summer or to keep warm during winter. The high moisture will significantly increase your energy consumption and, consequently, your bills.

A vapor barrier keeps moisture from concentrating in the walls of a building, lowering the chances of excess humidity. It’s a sheet made of a material impervious to water, causing excess moisture to diffuse rather than concentrate.

A vapor barrier installed in a wall assembly during construction.
The best time to fit a vapor barrier is during construction of a wall, or when extensive renovations are being done.

Thanks to the vapor barrier, moisture doesn’t seep through your walls or affect the air inside your home—they act as insulators that keep your house protected. 

As a result, you stay warm during the cold periods and cool when it’s hot outside. Thus, you use much less energy for air conditioning, increasing the efficiency of your home and lowering your energy bills.

What Is a Vapor Barrier?

As explained earlier, a vapor barrier is a sheet made of special material that keeps your house insulated, diffusing moisture and not allowing it to permeate through your walls and floors. 

When building or looking for a new house, you should always consider the amount of humidity your new home will likely be exposed to. Water from the soil around the foundations of your house can go up your walls, floors, and ceilings, causing significant damage not only to the structure of your home but to your quality of life, too.

Moisture can go through any building material, whether hard or resistant. However, homeowners can put certain materials inside the structure to diffuse the water, preventing it from causing damage.

Vapor barriers are usually made of plastic, foam, aluminum, or steel. The thickness of the sheets varies, from thin and flexible to sturdier ones. 

These should be completely impenetrable, stopping water from going through. There are also sheets made of materials that allow water to go through at a much slower rate, called vapor retarders.

Where Should I Install My Vapor Barrier for More Efficiency?

There are regulations in place for installing vapor barriers in a building.

The general rule of thumb is to install a barrier on the side of the wall that is likely to absorb moisture and heat. This application helps to insulate the house from humidity and to retain or release heat properly, thus increasing efficiency.

Depending on the climate in your location, this rule may apply differently. You should install the barrier on the outer surface if you live in a hot and humid climate. 

Photo of the exterior of a home under construction with a vapor barrier installed, waiting for exterior cladding.

In contrast, the inner surface could be more insulated from moisture and heat if you live in a cold climate. Using this logic to install your barriers can help you save on energy bills.

However, you may live in a mixed climate, so you’re wondering what to do in this case. The truth is that there is no rule set in stone for these instances, so you’ll have to weigh your options. 

If there are higher chances of extreme heat over extreme cold, install the vapor barrier on the outer side. If the opposite is more likely, the barrier could help lower your bills if installed on the inner surface.

Other Advantages of Vapor Barriers

Energy efficiency is only one of the aspects in which vapor barriers are helpful. Still, insulating and diffusing moisture can provide many other benefits, not only for the building but for you and your loved ones.

Health Benefits

As we mentioned above, vapor barriers diffuse moisture, reducing humidity in the air and improving air quality. They also prevent the development of mold and mildew around your house, which can cause severe allergic reactions and even contribute to respiratory illnesses. 

Moreover, by preventing moisture from concentrating, they reduce the possibility of bacteria-related infections and diseases. 

Most bacteria thrive in environments with ample humidity. Consequently, allowing excess moisture to seep through your walls could attract different types of bacteria, putting your health at risk.

One significant benefit is that vapor barriers can protect you from radon, a harmful gas that can cause cancer. A good quality barrier can insulate your house and stop radon from entering your living space.

Rot, Mold, and Rust Prevention

Moisture concentrating on the walls can result in mold and mildew around your house, especially in areas that are not adequately ventilated. As a result, they can damage your home and your health, in addition to causing an unpleasant smell.

The humidity from your walls can also reach your wooden floors or furniture, causing them to rot and leading to significant harm. Additionally, if you have any equipment or components made of metal in your house, they may develop rust because of the humidity. 

a rotten subfloor in the hallway bathroom with a hole in the floor
We had to replace the subfloor in our second netzero home renovation due to water damage and rotting through the decades.

A vapor barrier that insulates your abode from moisture can help avoid all these problems.

Pest Prevention

Pests thrive in environments with high moisture. Unfortunately, the water concentration attracts all kinds of bugs, including termites and stink bugs. Once they find an ideal space, getting rid of them is quite challenging. 

Using a vapor barrier deters these pests in the first place by preventing humidity from concentrating in your house.

Reduced Risk of Electrical Issues

Wires are usually insulated pretty well, but they can get damaged, causing them to become vulnerable and, therefore, extremely dangerous. If moisture concentrates nearby, you risk electrical issues at best and fires or electrical shock at worst. You can avoid this problem by installing a vapor retarder or barrier.

Is a Vapor Barrier Necessary?

As you can see, a vapor barrier offers many benefits. Still, you may wonder if it is necessary for every house out there. While it is very beneficial, a barrier is not strictly required. Check your local building codes to see if it is a requirement where you live.

A few factors can determine if a vapor barrier should be installed in your house, including:

  • Climate
  • Cladding
  • The location of the walls where you will install it 
  • The level of permeability you want the barrier to have

 If you want to know more about this issue, check out our article discussing instances in which you may want a vapor retarder or barrier.


Vapor barriers are incredibly beneficial and sometimes necessary to protect your house from humidity. They help insulate the dwelling, enabling it to retain heat when it’s cold outside and release it when it’s hot. Depending on the climate, they might need to be installed differently.

Additional benefits of installing vapor barriers include preventing structural damage from rot, rust, and mold and avoiding electrical issues. Moreover, they can protect you from several health problems.

So do yourself, your home, and your family a favor and have one installed today!


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