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Crawl Space Vapor Barrier Thickness

A vapor barrier is essential in keeping you crawl space clean, safe, dry, sealed from outside moisture, and less attractive to pests. How thick should your vapor barrier be, and is it effective in encapsulating your crawl space?

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What’s the Difference Between Crawl Space Vapor Barrier Thicknesses?

Most homeowners don’t know a lot about home repair. That doesn’t have to be a bad thing; after all, it’s not your specialty. However, that can lead to problems when homeowners believe a fix is much more simple than it actually is.

One place this sometimes shines through is in crawl space vapor barriers. A crawl space vapor barrier helps keep moisture from the soil outside your crawl space. That’s important if you want to avoid crawl space mold, crawl space mildew, and other problems.

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There are many different vapor barrier thicknesses. If you’re not well-versed in-home repair, you may not know the difference between them. With this information and a JES expert on your side, you can understand why it’s so important.

Let JES determine if your uneven floors are caused by house settling which may require foundation repair.

The Most Common Crawl Space Vapor Barrier Thicknesses

Crawl space vapor barriers are rated by “mils.” Although it looks like an abbreviation for “millimeters,” “mils” actually aren’t the same as millimeters. Instead, one “mil” is one one-thousandth of an inch. With such a small unit of measurement, it’s much easier to see why even seemingly minor differences can make a serious impact.

There are a few common crawl space vapor barrier thicknesses you’ll probably run across if you’re looking for a crawl space barrier.

Barrier Thicknesses

6-Mil Barrier

The thinnest barrier is typically a 6-mil barrier. This is the thinnest because barriers any thinner than 6 mil will typically tear extremely easily. A too-thin barrier may even tear just while laying it down in the crawl space.

Many people are tempted to install 6-mil vapor barrier liners in their crawl spaces trying to cut costs. However, their attempts to save money end up costing them more money in the long run. Prior building code requirements permitted the use of 6-mil vapor barrier liners and many individuals installed them in their crawl space to meet the bare minimum. But the bare minimum does not provide the best results.

To give you an idea of what a 6-mil barrier would look like, consider the fact that most plastic grocery bags and some bargain brand trash bags measure around three mils at the thickest. Would you want to lay down two grocery or trash bags to protect against crawl space vapor? Probably not.

10-Mil Barrier

A 10-mil barrier is less common than 6 or 12-mil barriers, but it’s still a thickness you might run into. This barrier fixes some of the problems you may experience with a thin 6-mil barrier, but because mils are so tiny, it, unfortunately, doesn’t tend to do a lot.

On average, most postcards are printed on paper that measures around 10 mils. The fact is, this often isn’t thick enough to avoid tears throughout the years, especially if someone ends up needing to visit your crawl space for some reason.

12-Mil Barrier

This is one of the most common barrier thicknesses around, and it has been the industry standard for some time. That’s because it’s twice as thick as the very fragile 6-mil barrier and generally affordable, which can make many homeowners feel more comfortable with this thickness of crawl space vapor barrier.

A 12-mil barrier is only very slightly thicker than a 10-mil barrier — to the naked eye, it’s essentially imperceptible. Although this can be an effective option for some people, it’s also not super durable. A 12-mil vapor barrier rips very easily and holes are poked in it whenever you crawl on it.

These flimsy liners are also very difficult to attach to walls and can be easily pulled down, and they may not completely prevent moisture and vapor intrusion.

15-Mil Barrier

A 15-mil barrier is slightly thicker and better than 6-mil, 10-mil and 12-mil vapor barrier liners. However, these types of barriers still do not compare to heavier vapor barrier options.

More than half of the air that you breathe in your house comes from your crawl space. Therefore, the 15-mil or thinner vapor barrier will not suffice in keeping your crawl space or home healthy.

20-Mil Barrier

This is typically the thickest barrier for home use. Much thicker vapor barriers exist, but they’re almost exclusively for heavy-duty construction jobs that need to withstand a lot of movement and potentially sharp edges.

JES uses CrawlSeal, a 20-mil 7-ply polyethylene crawl vapor barrier that’s high-performance and low-maintenance. Essentially, JES uses it because it’s effective and unlikely to tear or puncture, even in less-than-ideal environments.

A 20-mil barrier is the best choice because it fully encapsulates the crawl space to isolate your home from the earth. It prevents moisture and vapor intrusion, has UV protection, and is treated with an antimicrobial additive to hinder the growth of mold and mildew underneath the liner and on top of it. CrawlSeal’s 20-mil vapor barrier liners are able to withstand added traffic making storage accessibility possible, and using a 20 mil vapor barrier can save 15%-20% on heating and air conditioning costs.

With benefits like these, why not use a reliable 20-mil vapor barrier?

crawl space encapsulation

Why Are Thin Crawl Space Vapor Barriers a Problem?

Why does it matter that the other vapor barriers are thinner than 20-mil? Do you really need a 20-mil crawl space vapor barrier, especially if you’re not planning on visiting your crawl space very often?

These are valid questions. Thin crawl space vapor barriers can cause more trouble than they’re worth for a number of reasons. 

Tears and Punctures

This is the biggest problem you’ll likely run into with thin crawl space barriers. Unfortunately, a thin crawl space vapor barrier just isn’t built to withstand almost any type of stress, and it’s likely to tear.

Plus, crawl space barriers don’t just tear because of physical stress. Especially thin barriers, including 6-mil barriers in many cases, may start to erode because of the moisture it’s keeping back. That makes it effectively unusable.

If you want a crawl space vapor barrier that’s going to keep functioning for many years, it’s a good idea to get a high-quality product. Don’t waste money on a crawl space vapor barrier that’s just going to break. 

Building Code Requirements

Building codes can keep you safe. They’re always updating with more safety protocols because even just a few missteps can result in a structure that’s liable to fall down and severely injure anyone who lives inside.

A 6-mil crawl space vapor barrier doesn’t meet building code requirements. Though you’re unlikely to have anyone point that out with a non-commercial home, it’s still a good idea to stick to building code if you want to stay safe.

Although a 10-mil crawl space vapor barrier may meet building code requirements, you typically don’t just want to meet requirements. If possible, you want to exceed them to create a truly safe structure for your family. 

Low-Performance and Low-Efficacy

At the end of the day, a thin crawl space vapor barrier won’t perform at the efficacy of a thicker one. If the barrier suffers even a very small puncture, you’re likely to run into insect problems, seeping moisture and humidity all over again.

Even if you’re not planning to go into your crawl space any time soon, you can’t guarantee you’ll never need to do so. If you have any issues in your crawl space, you want to make sure someone can look around without having to replace the crawl space vapor barriers.

It’s just a good idea to opt for the high-performance crawl space vapor barriers when you first install them. A JES expert will always recommend a CrawlSeal 20-mil vapor barrier for the best results.

encapsulated crawl space

Crawl Space Vapor Barriers in Encapsulation

Typically, you’re going to use a crawl space vapor barrier for encapsulation. This is a process whereby you block out all moisture coming from the soil of a dirt floor crawl space. It plays a major role in making sure your crawl space stays dry.

What does a crawl space do for encapsulation? These are the main things a high-quality crawl space vapor barrier will do. 

Keeps Soil Moisture Out of Your Home

This is the most important part of what a crawl space vapor barrier does. Soil always seeps moisture into your home, even if the top few inches are as dry as possible. You need to lay down a crawl space vapor barrier to avoid that.

That’s why it’s so important to have a thick crawl space vapor barrier. If your crawl space vapor barrier is too thin, it may also be very permeable. That’ll let soil moisture into your home even if it doesn’t develop tears or punctures.

A JES expert will be able to install a CrawlSeal 20-mil vapor barrier properly. That means it’ll keep out the moisture it’s supposed to keep out. That’s what it’s supposed to do, so you need a barrier that’ll stand up to the task. 

Easily Seen Moisture

You want to know if there’s moisture in your crawl space. If you find moisture in the crawl space after encapsulation, it means there’s something wrong — either the encapsulation isn’t full, or there’s water coming from somewhere else.

A crawl space vapor barrier allows moisture to collect on the barrier. That makes it much easier to see when someone goes down to the crawl space to do an inspection.

When a JES expert performs an inspection of your crawl space, it’s always better to be able to see any moisture collecting anywhere, whether it’s condensation or full-on standing water. A crawl space vapor barrier will show that plainly. 

Allows for a Clean, Dry Crawl Space

Moisture is your crawl space’s ultimate enemy. That’s why you should invest in a crawl space vapor barrier: it’ll help keep out the moisture that’s always going to be a problem if you have a crawl space with a dirt floor.

It’s near impossible to maintain a clean or dry crawl space with a dirt floor. After all, you can’t clean dirt: there’s nothing under it to show that it’s clean. A crawl space vapor barrier provides a clean surface for your crawl space.

When you consult a JES expert, you’ll be able to get more information regarding how a crawl space vapor barrier can help you with a moist crawl space. Then you’ll be sure it’s installed by professionals who know exactly what they’re doing.

encapsulated crawl space

Utilizing an Expert’s Touch for Crawl Space Vapor Barriers

There are some home repairs you can do yourself, which leads many homeowners to ask whether they can DIY more substantial repairs and installations. Crawl space vapor barriers definitely aren’t one of the things you can do yourself.

If you need to install a crawl space vapor barrier, you need to rely on a JES expert to do so. These are just a few of the things an expert brings to the table. 

Thorough Encapsulation

When you have a crawl space encapsulation, you want to make sure it’s done right the first time. There’s nothing more frustrating than assuming your crawl space is free of moisture, only to find out it’s actually full of moisture because the encapsulation wasn’t done right.

You want to make sure you’re fixing the problems that may be popping up due to crawl space moisture. Encapsulation can fix those problems, but only if it’s performed properly.

When you’re consulting an expert for encapsulation, it’s important that you trust the expert you’re talking to. JES professionals are trusted by a large variety of people because they always perform quality work that actually fixes the problem. 

No More Foundation Issues

If you have too much crawl space moisture, you’re probably also going to start having foundation problems. The moisture can start to eat away at your foundation, causing serious problems that will have continuing effects.

A crawl space barrier takes steps toward avoiding those foundation issues. Without the moisture that eats away at your foundation, you’re less likely to have very serious problems, including but not limited to uneven floors, mold, and structural instability.

During a free inspection from JES, an expert will take a look at your foundation as a whole. If they notice a foundation problem that you need to address, they’ll let you know exactly what the problem is and how you can fix it. 

Effective Moisture Management

There are many ways to manage moisture in your crawl space. Even after encapsulation, you may need to install a dehumidifier to keep the area fully dry. Prior to encapsulation, you’ll also need to pump out any standing water.

Most homeowners don’t know this process. It’s definitely possible for you to miss some of these steps, and that can lead to lasting moisture problems that can have serious impacts on your home as a whole down the line.

JES experts know all of these important steps, from the big ones to the small ones, and they know how important each step is. A JES expert can help you perform the steps you need to perform to keep your home stable for years to come.

Frequently Asked Questions About Crawl Space Vapor Barrier Thickness

Many people have questions about the best crawl space vapor barrier thickness. What’s the best way to handle your crawl space vapor barrier?

The first question many people have is, what is a moisture barrier for a crawl space? A crawl space plastic vapor barrier is a crawl space ground cover that helps prevent moisture moving from the ground to the crawl space.

As the name implies, a crawl space or encapsulation vapor barrier makes sure that water vapor doesn’t pass through. In that aspect, it may be more accurate to refer to it as a crawl space water barrier.

In some areas, the building code may require crawl space encapsulation plastic depending on if you have open crawl space vents. A crawl space repair expert will give you more information on the requirements you may or may not have.

A vapor barrier for crawl space isolation is an important part of maintaining the health of your crawl space. It’s important that you get a high-quality crawl space vapor barrier material so that you get the most use out of it.

The best advice is to make sure you talk to a crawl space repair expert and have them install 20mil vapor barrier in your crawl space. Don’t try to DIY this important fix; allow an expert to help you take care of it.

When you put in a 20-mil crawl space vapor barrier, you’re going to use a thick plastic barrier. This plastic barrier helps you keep the water vapor barrier on one side. That’s why a true crawl space repair expert will recommend a thick, strong 20mil vapor barrier for your crawl space.

In some cases, you might see someone claiming that a cheaper 12–mil vapor barrier is fine for your crawl space. The comparison between the 12–mil vs. 20–mil vapor barrier goes much deeper than just the cost, however. If you choose the higher-quality 20–mil vapor barrier for your crawl space, you’ll be more thoroughly protected from moisture.

Your crawl space needs a 20-mil vapor barrier to get the maximum benefits of a crawl space vapor barrier. If you want the benefits from a CrawlSeal™ 20–mil crawl space vapor barrier, you should schedule an inspection with a JES expert to discuss your options.

A JES Expert Can Help You Encapsulate Your Space

You don’t need to personally choose the right crawl space vapor barrier. You also don’t need to try and encapsulate your space on your own. Those are things a JES expert can help you with.

If you’re having foundation problems, if you’re experiencing standing water in your basement, or you know there are moisture issues in your crawl space, you should get in contact with a JES expert for a free inspection. During that free inspection, the expert will determine exactly what’s wrong and exactly how to fix it.

With a free inspection from JES, you don’t have to worry about whether or not you’re experiencing problems that will come back to bite you in the future. You can just be confident in your safety.

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