Many years ago, people used to think that crawl space vents would keep a crawl space dry and moisture-free by letting the moisture out. Many dirt crawl spaces ended up with vents for this reason. Unfortunately, over the years, it’s proven to be just the opposite.
Crawl space vents, we now know, actually let more moisture into the area. Because these vents are introducing outside air into the crawl space, there’s just no way to make sure all that air is of a high enough quality to feel comfortable breathing it.
Today, we know that there’s simply an unavoidable problem with dirt crawl spaces: they won’t ever actually stay dry and healthy on their own. If you’re looking to discover the benefits of crawl space encapsulation, here’s everything you need to know about the science behind it.

Crawl Space Problems, Solutions, and Professional Guidance
Learn more about crawl space problems including moisture, how to permanently address these issues, and how the professionals at JES can help.
Crawl space vents typically exist in dirt crawl spaces. These crawl spaces sit directly underneath the house with no barrier between the home and the dirt underneath it.
This can be a serious problem. Dirt crawl spaces introduce all sorts of issues into the mixture. These are just a few of those problems.
Unavoidable Moisture
The first problem with a dirt crawl space may be the most important one. To put it simply, there’s absolutely no way to avoid moisture coming from a dirt crawl space. You’re always going to have more crawl space moisture coming up, and crawl space vents aren’t going to do anything to avoid it.
Sure, you can dry out the top layer of the dirt in your crawl space. However, that won’t do anything in the long run. Only a few inches below the surface, you’ll find moist dirt, and that moisture will always rise to the surface.
Plus, far from venting that moisture, crawl space vents tend to actually reintroduce moisture into the area. The only way to avoid moisture in a dirt crawl space is to seal the crawl space vents and box off the dirt bottom.
Insects and Mites
Dirt is also impossible to keep clean and free from bugs. Think about it: you’re trying to move bugs out of their natural home. It’s just not plausible. That’s why dirt crawl spaces tend to be plagued by mites, insects, and other pests.
Crawl space vents can also add to this problem. After all, if you have open crawl space vents, it’s essentially just another way for pests to enter your crawl space. Then they can just stay in your crawl space until further notice.
The only way to make it difficult for insects and other pests to get into your crawl space is to seal the crawl space entirely. Otherwise, you’re fighting a losing battle against these pests.
The Stack Effect
It may surprise you to learn that over half the air on a home’s first floor comes from the crawl space, but it’s the scientific truth. This is mostly due to a physics concept called the “stack effect,” which refers to the way in which air moves up through your home.
Air is always moving, and in your home, it’s typically always rising from the bottom to the top. When you have replacement air moving in from the vents in your crawl space, it creates an effect similar to a chimney, bringing the air in your crawl space up into the rest of your home.
That stack effect also brings with it moisture, mold spores, dust mites, and other airborne features that would otherwise stay down in the crawl space. You don’t want un-conditioned air from the outside becoming part of your home, but the vents in your crawl space do just that.
Potentially the most serious reason you should avoid a dirt crawl space is because of moisture. Moisture can wreak havoc on your family and your home.
There are many reasons moisture can be harmful to your home. These are just a few of those dangerous reasons.
A Breeding Ground for Mold and Insects
Moisture is great for mold and pests. Mold spores truly thrive in moist environments, and if your crawl space stays moist and warm, you’re essentially inviting mold into it.
Remember, the stack effect brings up air from your crawl space. If that damp air has bred mold spores, those mold spores will come up into your house, invading your home and infesting the air you’re breathing.
The best way to avoid this is by sealing your crawl space vents. When you seal foundation vents, you’re cutting off the stack effect at the root.
Structural Damage
Water is organic material’s worst enemy. Many homes with dirt crawl spaces also rely very heavily on wood for many pieces of the home. The moisture from the crawl space can severely impact the wood structure.
Unnecessary moisture can cause wood rot, destroy drywall and even start eating away at stone foundations. Plus, mold spores can also do their part to start eating away at these structures.
When you have too much moisture, your home’s structure is going to start failing. That’s unfortunately just an intrinsic part of the issues associated with excess moisture in your home. The only way to fix it is to seal the crawl space.
Increased Energy Costs
Did you know that you might be overpaying dramatically for energy consumption? Your crawl space vents are letting in air from the outside, which you then have to run through your air conditioning units over and over again.
Additionally, humid air takes more energy to cool. You may be feeling like it’s warmer in the home than it actually is just because the moisture in the air is fooling you into feeling warmer.
This can be a great reason to take the plunge and learn how to seal crawl space vents. Even though it can cost money to seal off, sealing a crawl space may actually pay for itself in reduced energy bills throughout the year.
Clearly, it’s important that you seal your crawl space. That’s not really negotiable. The next question is how to seal a crawl space vent.
The most recent zoning and coding requirements actually provide a lot of insight into this problem. You can learn exactly how to seal foundation vents the right way.
Complete Top to Bottom Sealing
First, it’s important that you seal the entirety of the crawl space. Moisture is tricky and finds its way through just about anything. If you miss any of it, it’ll end up seeping into the rest of your home.
Crawl space encapsulation only works when it’s genuinely encapsulated. You need to make sure you’ve sealed the foundation vents, covered the dirt floor, and fixed any cracks or leaks in the foundation.
Remember, it’s much better to get the job done right the first time. That’s especially true with sealing a crawl space because you’re unlikely to realize you’ve done the job incorrectly until months down the line.
Extra-Heavy Reinforced Lining
It’s common for inexperienced individuals to try and use a very thin tarp when lining a dirt crawl floor. This thin lining covers the ground, but it doesn’t do much else.
It’s extremely important that the lining you use doesn’t have any chance to break, tear, or otherwise collapse. An extra-heavy liner makes sure it doesn’t accidentally break, but it also keeps insects and critters from managing to create a break in it.
This reinforced lining may include many layers of different materials to stop moisture leaking through. It’s also often treated with an anti-microbial finish to make absolutely sure it’s hostile to mold and mildew that may otherwise grow.
Dehumidification and Air Filtration
Last, but certainly not least, you may need to install a dehumidifier or air filtrating unit in your crawl space. Although this can be difficult to install, it’s important if you’re having particularly difficult problems.
Remember, even once you’ve sealed the crawl space, the air in your crawl space will still rise into the rest of your home. You’re always better off playing it safe.
If you do need this kind of heavy-duty protection, a JES expert can let you know. This isn’t necessary for every home, but your home may require special treatment.
It can be expensive to fix up a home. If you’re trying to save money, you may wonder how to seal a crawl space yourself. Is it possible?
The knowledge of how to seal off crawl space vents is generally best left to the professionals. That’s because the professionals know what they’re doing and can offer you the best possible outcome. This is what experts bring to the table.
Up-to-Date Knowledge
Information about home repair is always changing. In fact, this is a great example: many years ago, the prevailing wisdom was to create crawl space vents. Now it’s to seal crawl space vents back up.
Home repair probably isn’t your specialty, which means you probably aren’t staying up to date on the latest information. However, a JES foundation repair specialist is staying up to date on all that information and can bring it to you.
It’s essential that you’re able to act on the latest information coming from the home repair industry. Only a professional will give you access to that information.
Encapsulation That’s Up to Code
Staying up to code is an essential part of staying safe. Home coding is always growing and changing as the information in the industry also grows and changes. You want to make sure your home stays true to that code.
As a DIYer, you might not know the intricacies of that code. When you change one thing, that may mean you also need to change a variety of other things to keep yourself safe.
You should instead trust someone who’s dedicated their whole life to making sure families and homes stay safe. It’s worth the peace of mind to just go with a professional.
Professional, Personal Advice
One of the most important things that an expert can bring to the table is the ability to offer you advice that you’ll actually want to take. In this industry, many businesses thrive because their experts are able to talk to customers and give them more information.
It’s hard to handle home repairs. It can be a long, frustrating, expensive process. That process can be even more frustrating if you run into someone who’s trying to oversell you on things you don’t need just to make some extra money.
One of the things JES prides itself on is its ability to tell clients exactly what they need and don’t need. If you can fix your crawl space moisture problems with a quick and easy patch, JES will tell you. That’s why people trust JES for home repairs.
Crawl Space Sealing: Your Next Steps
Now that you know what’s wrong with your crawl space, what next? Where do you need to go after this? How do you seal your crawl space most effectively?
First off, if you have a dirt crawl space or open crawl space vents, you need to take care of them. They may be contributing to high energy bills, home discomfort, structural issues, and even health concerns for you and the members of your family. You can’t just let these go unchecked. It’s important that you seal crawl space vents and the crawl space as a whole.
If you’re looking for a way to do that, get in touch with JES today. You can book a free inspection to learn more about what’s going on under your home. With that specialized knowledge, you can then move forward into fixing it.
Don’t let your home potentially deal with serious damage and health hazards. Book a free inspection with JES today to tackle your problem at the source.