The roof of a home under construction with a vapor barrier partially installed

Your HVAC system helps control the moisture level in your home, but it doesn’t have to do that job alone. Vapor barriers will keep your space dry by locking moisture out when installed in notoriously damp places, like attics, crawlspaces, and basements. 

However, what are the pros and cons of vapor barriers, and are they really worth it?

This post will explore all the advantages homeowners like you will enjoy from installing vapor barriers. However, we’ll also consider some of their downsides to help you decide whether they’re the solution you’re looking for. 

So, let’s get started!

What Are the Pros and Cons of Vapor Barriers?

The benefits of vapor barriers include temperature control, lowered energy costs, reduced insects and mold, and erosion protection. However, they’re hard to install, may necessitate upgrading your HVAC, can be expensive, and need regular maintenance. 

Nevertheless, they’re worthwhile if you live in a humid climate.

Now let’s consider these advantages and drawbacks more in depth.

Pros of Installing a Vapor Barrier

Vapor barriers make for an elegant and straightforward way to limit moisture levels in your home. However, if you need more reasons to consider vapor barriers, here are some other, sometimes overlooked, benefits.

Temperature Control

Sealing moisture away means vapor barriers do more than keep a room dry. A byproduct of this function is temperature control. It all comes down to how a vapor seal limits humidity in the installed space.

Moisture in the air creates humidity by hindering our body’s ability to regulate sweat. Too much moisture means we cannot cool ourselves, leaving us feeling that the temperature is higher than it actually is. By contrast, low humidity makes us feel cooler.

By keeping moisture levels in check, vapor barriers keep the temperature in your home relatively consistent. Usually, higher points in a home, such as an attic, are more humid as heat rises through ceilings and floors. Barriers are a simple, effective alternative to manually tracking down such airflow points and sealing them individually.

An unfinished attic with a partially-installed vapor barrier

This application is also beneficial for the lower areas of your home. Moisture can seep into the wood and, in doing so, transfer from one place to another over time. Vapor barriers prevent this movement by locking most moisture outside of designated rooms.

Extending the Life of Pipes and Ductwork

Moisture’s effect on how we perceive air temperature is a problem, but it can have a destructive effect on metals throughout the home. When moisture trapped in the air makes contact with metal, it begins the process of corrosion. The chemical reaction leads to oxidation, rust, and eventual deterioration.

When the ducts that connect your HVAC system fall victim to corrosion, it will start to falter. Deterioration will eventually result in a hole, allowing air to escape when the HVAC is on. Moreover, the system will work even harder as it fails to regulate air temperature, putting its components at greater risk of failure.

Inhibiting moisture will significantly extend the life of metal throughout your home. Between plumbing and HVAC, it will also help support air quality. That said, it’s essential to remember that vapor barriers are not substitutes for proper air duct sealing

A technician applying metal-backed tape to an cylindrical duct to prevent air duct leakage

Insect Infestation Prevention

Nobody wants to deal with a pest infestation. Unfortunately, in 2019, the US Census Bureau reported that about 124 million housing units had roaches. Other bugs, such as ants, termites, bees, and wasps, are known to take root in homes with unattended openings.

Structural damage allows insect infestations to occur, and addressing these requires diligence and (usually) construction work. 

However, without such damage, vapor barriers can block seemingly insignificant openings that insects could otherwise take advantage of. They also help by reducing the moisture that attracts certain pests.

It’s important to know that installing a vapor barrier after bugs have already made your home theirs will only prevent new invaders from coming in. Anything already inside your home requires addressing through other means. 

So putting a barrier in place as soon as possible is the best way to keep pests out.

Slowing or Stopping Mold Growth

People sometimes associate mold with old surfaces or organic material and think it takes years to grow. In reality, mold proliferates quickly. Mold can grow on a wet surface in as few as one to two days.

Mold eats the organic surface it develops on, eventually wrecking it. But, at the same time, it releases spores that, upon landing on a damp surface, continue the growth process, destruction, and reproduction. This way, mold grows and spreads faster than you may expect.

A homeowner helding his head looks in disbelief at mold growth in the corner of the wall under his bathroom cabinet

Though the most dramatic mold growth results from extensive water damage (like a burst pipe), any source of moisture will do. However, if a vapor barrier is in place, you can keep your crawl space or basement dry enough to prevent mold from growing inside the area. 

Unfortunately, this also makes for a potential downside, but we’ll discuss this more in-depth in one of the following sections.

Boosting Energy Efficiency

Previously we touched on how a properly installed vapor barrier can protect your HVAC system by preventing corrosion. However, it can also reduce energy costs by ensuring that the heated air stays within your home. 

With humidity in your home under control, you’ll spend less on energy bills to keep your home warm. Of course, keeping moisture out helps keep things warm, too, especially in winter.

That dampness in colder seasons can have a chilling effect on your home. But, with a vapor barrier, that moisture won’t have the opportunity to seep in and absorb that much-needed heat.

Increased Resale Value

If you’re considering selling your home down the road, you need to monitor what you can improve closely. 

Besides maintaining an appealing exterior appearance, keeping the interior pristine can add to the final sales price. However, preventive maintenance can go a long way, and that’s where vapor barriers are beneficial.

Vapor barriers can increase your home’s resale value in two ways. First, as preventive maintenance, they can minimize certain types of damage that can gradually harm your home. Second, they show potential buyers that you put in the extra effort to take care of the home.

Buyers don’t want to spend time fixing things the previous owner didn’t address. Vapor barriers help minimize unexpected problems after they buy a home. Additionally, it can save them money since they won’t need to install any themselves.

Cons of Installing a Vapor Barrier

As with any home improvement project, installing a vapor barrier comes with its own complications and risks. Take the following issues into consideration before you commit to a vapor barrier.

Expensive Installation

A hardhat, roll of vapor barrier, and staple gun sitting atop a piece of OSB

The overall cost of a vapor barrier depends on three variables—materials, size, and labor. Vapor barriers come in different varieties, like foil or plastic, but some specialty varieties made with a more complex blend of materials will cost more. 

The size you’ll need generally depends on the space you’re sealing, with Home Advisor estimating between 50-70 cents per square foot.

Labor costs can vary wildly based on the installation space. Moreover, adjustments are necessary when installing vapor barriers around doors, pipes, and ducts, which requires great precision. While doing it yourself isn’t impossible, it requires a lot of preparation to be done correctly.

Pinning down an average cost for labor is difficult, but most estimates range between $1,000 and $4,000. That’s a small investment compared to other home improvement projects, but it’s still a large sum of money overall. Thus upfront costs can make buying and installing vapor barriers difficult for some.

They Often Need Replacing

By now, we’ve covered how expensive it can be to install vapor barriers. 

So naturally, you’ll want to be careful around them to keep them in the best shape you can. Unfortunately, these barriers are delicate, and even minor damage can necessitate a total replacement, putting you back at square one.

Many things can damage your vapor barrier, but the most common are water sources from within the sealed space, damage from pests, or work done on adjacent floors and ceilings, like wiring. 

If you don’t address the first two before installation, they’ll inevitably ruin the seal. Unfortunately, the last case often occurs accidentally and is not immediately noticed.

Additionally, it would help if you considered what your local building codes require, which is another reason to hire a professional for your installation. They can point out the additional work you need before considering installing a vapor barrier. Unfortunately, this will inevitably increase labor requirements and costs.

A serviceman installs a vapor barrier on the ceiling in a basement

If you’re looking for a solution to your moisture problem that you can put in place and forget about, you’re out of luck. Vapor barriers require occasional attention to ensure they’re in working order. And if you do need to replace them, doing so quickly is vital to reducing the damage caused by the broken barrier.

Interfering With Your HVAC System

By controlling how humidity can enter and exit a designated space, vapor barriers can hinder your HVAC system’s ability to do its job. 

While vapor barriers are designed to keep moisture out of a sealed space, it doesn’t prevent humidity from occurring naturally. As a result, condensation can still develop on the walls behind the barrier, causing damage. 

It’s a known issue with homes utilizing central air systems. In regions with low temperatures, or during winter months or extreme cold, the space between the barriers and the wall becomes ideal conditions for mold growth. 

In some circumstances, it’s possible to avoid this problem by upgrading your HVAC system. What it means to upgrade an HVAC system depends on the components. 

It could mean adding or replacing some parts to boost efficiency for recent systems. However, older systems may need replacing, requiring extensive work throughout the home.

The best way to anticipate if a vapor barrier will be a problem for your HVAC system is to hire an HVAC professional. They can review your system, see how it works throughout your home, and tell you if you need to update it before effectuating the barrier. But in any case, it’s another potential cost to weigh.

Installation Mistakes Can Be Damaging

Installing a vapor barrier isn’t as easy as you might assume when looking at the final product. Not only does each piece need precise placement, but ventilation features in the room complicate the installation process. Even slight errors leave openings and render the barrier useless. 

However, it’s not always easy to spot poor installation. Spotting the signs require you to pay close attention to the barrier, the encapsulated space, and how the air feels. The most obvious sign will be water in the area or on the wrong side of the barrier. 

It’s a complicated problem to correct. Not only do you most likely need to remove the old barriers and install new ones, but you’ll have to find any sources of water that you didn’t address previously. Anything from standing water to discrete leaks could be the source.

A puddle of standing water in a crawl space
Courtesy of Foundation Repair of Western Colorado

The best way to avoid a quagmire like this is to hire a professional to handle the installation. It’s essential to understand that accidents still happen, and mold only takes a small amount of trapped moisture to start breeding freely. 

All in all, whether you should use a vapor barrier or not comes down to your unique circumstances, so make sure to take all the previously mentioned advantages and drawbacks into account before making a decision.

Final Thoughts

Vapor barriers are an excellent addition to any home in a humid climate, but they don’t come without drawbacks. Whether or not you should install one ultimately comes down to the environment you live in and how prepared you are to address problems with the barrier down the road. 

While they have a high upfront cost, which gets even higher when considering upkeep, they can save you a lot of money in the future by protecting your home.


Leave a Reply

Your email address will not be published. Required fields are marked *