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Bad Vapor Barrier

Crawl space waterproofing is one of the best things that you can do to protect your home—as long as it is done well. Having a bad vapor barrier, for example, is worse than having no vapor barrier.

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Properties in Missouri can benefit greatly from crawl space waterproofing and, in particular, a good vapor barrier. After all, your crawl space is one of the most exposed areas on your property. 

When it is not properly encapsulated, your crawl space can become a real hotspot for things like dampness, mold and mildew, pest infestation, and even flooding. This is why crawl space waterproofing is so often implemented along with other crawl space repairs. 

Of course, crawl space waterproofing is only as good as the quality of products used and the skill level of the person who undertakes the work for you. 

When Crawl Space Waterproofing is Needed 

bad vapor barrier ducts mold

Crawl space waterproofing can take many forms. This is a highly flexible process that is tailored to meet the needs of the particular property that’s being waterproofed. Thankfully, the signs that waterproofing is needed in a property are much more uniform and, as a result, easy for even a non-expert to spot. 

Wet Walls/Flooring 

If you notice dampness or condensation on your crawl space walls or floor, it is time to consider waterproofing the space. This can be a sign of either high levels of relative humidity in the space or an indication that your home is being affected by seepage. Because seepage is generally not a result of damage to a surface, but a by-product of the naturally porous nature of concrete, waterproofing tends to be the only viable solution. 

High Relative Humidity 

High levels of humidity within a property can be a warning sign for many different issues, some of which may need more than a little waterproofing to ensure that your home is safe, dry, and hygienic going forward. Nonetheless, if you have structural damage that is allowing moisture into your home and raising the humidity (for example, bowing walls), waterproofing measures will often be suggested after repairs have been implemented to help prevent further issues from arising. 

Mold Formation 

If you notice mold formations in your property or crawl space, this is a sign that the humidity in your home has reached levels that are no longer healthy. Mold and mildew can spread with alarming speed and will have a number of side effects that can affect both your home and your health. For example, certain species of mold can cause skin irritation and even exacerbate pre-existing respiratory conditions. 

Musty Smells 

If you notice a pervasive, musty smell in your home that has seemingly no source, it is time to check your crawl space. Musty smells are most often caused by persistent dampness, unchecked mold, and wood rot. Only by addressing the issues will it be possible to remove the smell. Waterproofing is often a part of this. 

Pest Infestation 

Pest infestations are common in non-encapsulated or waterproofed crawl spaces, and they can be very damaging as well as unhygienic. Rodent infestation, for example, can cause damage to any pipes or wires that go through your crawl space, while cockroach infestations are unhygienic and can lead to issues with your health and well-being. 

Crawl space waterproofing will often be a part of the repair process, or a follow-up to it, because of the many benefits it offers to a property in both the immediate and long-term sense. 

How to Recognize a Bad Vapor Barrier 

Whether your property has crawl space waterproofing measures already, you are looking to upgrade, or you are considering waterproofing for the first time, it pays to be aware of what makes a certain product appropriate for your home. Recognizing a bad vapor barrier can be tough if you’re not an expert, but there are simple things to keep in mind. 


Vapor barriers come in a range of thicknesses that are suited to different surfaces, terrains, and levels of use. A 6-mil vapor barrier, for example, is extremely thin and delicate. It should not be used on a surface that is rough or uneven, or in a crawl space that is likely to have people moving through it with any regularity. By contrast, a 20-mil vapor barrier is much tougher, suited for even rough or uneven surfaces and can handle a crawl space that is being used as a storage space. We recommend 20-mil vapor barriers simply because they are far more effective and likely to survive long-term use. 

Tear/Puncture Resistance 

Thicker vapor barriers are, of course, more resistant to damage, but certain brands also offer superior tear and puncture resistance. Here at Foundation Recovery Systems, for example, we favor the CrawlSeal™ vapor barrier system for its incredible durability. 

Mold Resistance 

Any vapor barrier will give you protection against mold and mildew by creating a safe, dry, and hygienic bubble inside your crawl space. Nonetheless, there are some vapor barriers that are treated to improve their mold-resistant properties. You should be able to find out if a vapor barrier has been treated in this way by asking your supplier. 


Finally, a good vapor barrier is one that is compatible with the rest of your crawl space waterproofing measures. This is a somewhat subjective criterion, of course, but crawl space waterproofing is a flexible process. 

It is important that you get a good vapor barrier that is going to act as an effective part of your whole waterproofing system. If you do not, things could go downhill quickly. A bad vapor barrier is not just ineffective but can be actively harmful to a property. 

The Damage a Bad Vapor Barrier Can Do 

If you have a poorly fitted, badly damaged, or otherwise unsuitable vapor barrier in your crawl space, you will see issues begin to crop up very quickly. Having a bad vapor barrier will fail to protect your home from issues like dampness and humidity, but there’s so much more to it than just that! 

Bad Vapor Barriers Trap Moisture 

The problem with a bad vapor barrier is that, while it will not necessarily prevent moisture from getting into your home, it will stop it from getting back out. Any water or moisture that enters your home through small tears or gaps in your vapor barrier will quickly become trapped. Unable to drain away or escape your crawl space again, this moisture can lead to a huge number of problems for the stability of your property and even your health. 

The most obvious and immediate, of course, is a sudden spike in humidity that will cause your energy usage and bills to rise quite noticeably. This will bring a whole host of other problems in time, of course, but the first things to be affected will be your HVAC system and the consistency of the interior temperatures of your home. 

Bad Vapor Barriers Create Hot Spot Spaces 

As well as trapping in water, bad vapor barriers create small hot spot environments where issues can grow exponentially. For example, an encapsulated crawl space with a compromised vapor barrier is likely to be closer to the temperature of your property than the world outside. This makes it the perfect environment for mold and mildew growth. 

It is also an ideal environment for many kinds of pests (especially when there is mold already in the space). Roaches, rodents, and spiders can all make their homes in your crawl space anyway, but a bad vapor barrier will make them even more comfortable in the space. Once these infestations take root, they are incredibly hard to get rid of, so it is best to instead prevent infestations from taking root in the first place. 

Bad Vapor Barriers Contribute to Structural Damage 

As well as the issues previously discussed, bad vapor barriers will increase the likelihood of certain kinds of structural damage. Wood rot, for example, is an issue that is common in crawl spaces with bad vapor barriers, precisely because of the hot spot atmosphere that allows dampness, mold, mildew, and pests to flourish. 

This will affect any wooden surface and structure that are exposed to the crawl space. For example, exposed wooden support joists in your crawl space will be very susceptible to wood rot in this environment. If this happens, you will quickly see signs of sagging and damage to the floor above. Over time, this can lead to many different issues, the most serious of which will be a collapsing floor or section of floor. 

These are just the main ways in which a bad vapor barrier will affect your home. It is important to keep in mind that these issues will also start to affect your home as a whole over time. Your crawl space may be isolated from your home, but it is not entirely separate. Pest infestations, dampness, and mold can all spread into your property at large if left unaddressed. 

Bad Vapor Barrier


Protecting your crawl space may seem like an unnecessary expense, given that you are unlikely to ever spend much time there. However, this could not be further from the truth. Installing a vapor barrier, along with other waterproofing measures, could be the best thing you do for your home. 

Vapor Barriers Stabilize Your Home’s Climate 

The interior climate of your home is incredibly important to its health and, of course, your well-being. Installing waterproofing measures, but particularly a vapor barrier, can help you to control both the levels of relative humidity and the overall temperature in your property (especially when paired with quality insulation. This has a number of benefits. 

First and foremost, a property that has lower humidity is safer and healthier, but it is the consistency offered by a vapor barrier that is most important. Properties that experience fluctuating humidity are also more likely to experience issues with temperature regulation. Humid air is more difficult to heat and cool, after all, which can lead to increased energy usage. It also puts your property at higher risk of things like bursting pipes after a snap freeze. 

It Will Be Difficult for Pests, Mold, and Water to Get In 

A good vapor barrier will also provide a solid and reliable layer of protection from things like drafts, leaks, seepage, flooding, and pest incursion. It does so by creating a seamlessly encapsulated space inside your crawl space that making the environment inhospitable for moisture, dirt, and pests. It will also make it more difficult for them to get inside. Of course, this is only effective if it is properly installed and uncompromised. 

When used as a part of an overall encapsulation process, vapor barrier installation will leave your crawl space clean, tidy, dry, and safe for use as a storage space. This not only gives you more room to play with (which is incredibly important) but will make undertaking work in your crawl space more pleasant for anyone who has to enter it. It also ensures that any problems within your crawl space are easy to spot, even from a distance. 

There are many different kinds of vapor barriers on the market right now. While it is true that each thickness of vapor barrier has its own strengths and weaknesses, a 6-mil vapor barrier is not very strong at all. 

6-mil Is the Minimum Recommended 

A vapor barrier that is 6-mil in thickness is the bare minimum when it comes to protecting your crawl space from dampness and other nuisances. Anything thinner than 6-mil would simply not give any lasting or noticeable protection for your property’s crawl space, but a string-reinforced 6-mil barrier will prove slightly more durable. Nonetheless, 6-mil barriers are an economical choice that’s favored when cost is the overriding concern. 

The drawbacks to this are the generally lower levels of durability that these vapor barrier display. A 6-mil vapor barrier is not only more vulnerable to tears and punctures during the installation process. It is likely to be damaged if anyone enters the crawl space to undertake work. This also means that they are less suitable for people that wish to use their crawl space as a storage space. The weight of boxes and consistent movement will be damaging to the liner. 

20-mil Barriers Offer Better Protection 

While 10-mil and 12-mil vapor barriers are an option, for the best results, we suggest that homeowners consider a vapor barrier of 20-mil in thickness. A 20-mil vapor barrier is one of the thickest and toughest available, especially when reinforced and treated with antimicrobial substances. This kind of barrier will offer superior puncture and tear resistance, as well as a longer lifespan in general. This makes it the best possible option for those who want to use their crawl space to store seasonal goods. 

However, it can be more costly outright. We recognize that it may not be ideal for those on a tight budget. However, the slightly higher upfront cost is deceptive in the case of vapor barriers. The actual cost of protecting your home is lower overall when you invest in good quality products.

Whether you have just moved into a property and noticed that the crawl space is in need of some love, or you live in a property that has a newly encapsulated crawl space with a sub-standard vapor barrier, it’s important to act quickly. Replacing a bad vapor barrier can save you a lot of time and trouble, but you shouldn’t do it alone. 

Improper Installation is Incredibly Damaging 

While you can buy a vapor barrier over the counter at any decent hardware store, it is not a great idea to attempt to install one alone. This is partly because of how difficult it is to get the right products for your property. Worse yet, you’ll face issues during the installation process. Installation of a vapor barrier is, technically, a simple process, but if you don’t know what you’re doing, it is very hard to get right. 

This is largely because of the diminutive proportions of the average crawl space. It is hard to maneuver in this kind of space and vapor barriers can be fragile in some ways. If you accidentally kneel on it or get it caught in a crevice while you install it, a vapor barrier can easily tear or rip. This will render it effectively useless to your crawl space. As such, it is best to let someone with experience do this for you. 

Professionals Give the Best Results 

Another problem with trying to replace your bad vapor barrier alone is that you are unlikely to get products of the same quality as a professional would, even if you go into your local hardware store armed with all the knowledge needed to ask for the exact product. This is because there are some products that are not sold to the general public. Professionals have access to these products directly from the suppliers or makers. 

This means that you get a better product, a smoother installation process, and a guarantee of satisfaction with any professional installation. While a professional installation should not experience any hiccups, accidents happen even to the best of us. If a professional makes a mistake, they will rectify it on the spot. This means that your home will never suffer because of accidental damage to a vapor barrier during installation. As such, you can kick back and relax, safe in the knowledge that your home is being taken care of. 

Waterproofing your crawl space can offer many benefits. From the security and health of your property’s structure to the health and well-being of your family, and even your finances, crawl space waterproofing can have a big impact. 

Immediate Benefits 

Properly waterproofing your crawl space in full (as well as installing a good vapor barrier) has many different benefits which will take effect on your home almost immediately. The most obvious benefits of waterproofing are, of course, lowered humidity and the removal of dampness in your crawl space, but there are others to consider. 

For example, any drafts being caused will be cut off immediately after waterproofing. This will prevent the stack effect from working on your home as a whole. This, in turn, will stabilize the interior temperatures and prevent avoidable fluctuations. The result will be a more comfortable and healthy home from the moment that the waterproofing is completed. 

Long-Term Benefits 

As well as these short-term, or immediate, benefits, waterproofing your property’s crawl space has many benefits which will take effect over time. The most obvious, of course, is the sharp decrease in the likelihood of mold, mildew, and fungal growths as well as a reduced likelihood of pest infestation. This means that your home is healthier in the long run. 

Secondly, waterproofing contributes directly to a higher level of energy efficiency in your home. This is partly because of the way in which it eliminates the stack effect and partly to do with the reduction in dampness. Combined with the installation of insulation, this process increases heat retention and energy efficiency, thereby lowering the cost of your energy bills over time. 

Why Choose Foundation Recovery Systems 

Dealing with crawl space damage and dampness is a complex task, but when you have the right people in your corner, it can be dealt with in no time at all. Here at Foundation Recovery Systems, we have more than two decades of experience in crawl space repair and waterproofing. No matter what’s going on in your Missouri home, we will help you to make it right. All you have to do is book a free inspection with our team. 

There is no obligation to book repairs with us, and you will be provided with a written estimate for all our suggested repairs and improvements. There’s really no reason to delay. 

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