Crawl Space Vapor Barrier

Offering you a Lifetime Vapor Barrier Warranty and No Cat Urine Odor Guarantee.

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  • Over 700 5-Star Reviews

  • Limited Lifetime Warranties

Is Crawl Space Vapor Barrier Necessary?

Crawl space vapor barrier is one of the most important items you should install to help control moisture. Properly installed crawl space plastic helps make sure your crawl space humidity is controlled. However, vapor barrier alone does little to control humidity.

Installing the wrong type of vapor barrier can cause cat urine odors to occur and enter your home. Installing it incorrectly can allow moisture intrusion. Make sure you choose the right vapor barrier, the right crawl space contractor, and the right install methods to maximize the benefits of crawl space encapsulation.

Brian Rector

Brian Rector

"The whole process was great. Everyone we interacted with was professional and courteous. Celeste was great. Russell, Chase, and Will were terrific and did a great job. We no longer run a dehumidifier in our cabin, which we were having to run even in the dead of winter. Would not hesitate to recommend to anyone"

Donna Claes

Donna Claes

"We've had a lot of work done on our home recently and these guys have been by far the best to work with. Russell, Chase, Will and Ethan were absolute joys to work with. They were very professional, cleaned up completely every day (I swear the garage was cleaner after they left than it was before they got there!)."

Wes Salyers

Wes Salyers

"Crawl space ninja is great. Celeste and the rest of the team did a great job at assessing the needs of our crawl space and applying the appropriate solution. They showed up on time, communicated well, and provided high quality service and products. I would highly recommend them to anyone."

Essential Guide to Crawl Space Encapsulation is one of the best resources available for homeowners to learn what all goes into proper crawl space repair. We have learned that a well-educated homeowner will not fall for slick salespeople making unobtainable promises at cheap prices. This free guide is a way to protect yourself as you begin your journey to choosing the best crawl space encapsulation contractor.

Why Does My Crawl Space Smell Like Cat Urine?

Crawl space odors like cat urine smells can originate from the vapor barrier. Vapor barriers that are reinforced can degrade and delaminate. When the reinforced vapor barrier separates, it holds moisture. The trapped moisture can grow bacteria and mold and begin to give off an odor similar to cat pee.

Crawl space vapor barriers installed incorrectly can also cause odors in your home. Throwing new plastic over old vapor barrier in the crawl space should never be done. The multi-layers of vapor barrier can trap moisture, mold, bacteria, and more just like the reinforced vapor barrier. The Crawl Space Ninja Encapsulation Vapor Barrier is solid and will not allow water to enter, but if installed improperly over mold-growing materials or old plastic, it can trap odors too.



"We live in a 50-year-old brick ranch in Atlanta GA. Now since Spring, we are smelling this bad smell. It is making me sick I believe. It smells a bit like cat urine type smell..... I have tried air cleaner, odor remover etc. with no luck. Crawl space is dry and at 40 percent humidity. I have a dehumidifier running. I am hoping the smell eventually dissipates but so far it is strong and we smell it in the living space when the AC runs. A subtle yet bad smell. What to do??? I spent a lot on the crawl space encapsulation. Didn't anticipate this bad chemical cat urine odd smell. Jeff Weikert, Atlanta, GA

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Crawl Space Vapor Barrier Material

The vapor barrier material used by Crawl Space Ninja is proprietary and uniquely developed for the Ninja Crawl Space Encapsulation System. When we started encapsulating crawl spaces we used the same plastic as everyone else. We quickly realized the off-gassing of cat urine type odors is a real problem of some reinforced plastic materials.


How Thick Should Crawl Space Plastic Be?

Many contractors and manufacturers of crawl space vapor barrier material mislead people about the thickness of the plastic. We found plastic sold and installed as a reinforced 20-mil vapor barrier that was actually 6-mil. The thickness of the plastic was being measured at the reinforcement, not the plastic. Also, never use plastic as a substitute for crawl space insulation. Insulate and encapsulate your crawl space properly for maximum comfort and energy efficiency.

Crawl Space Ninja installs a 12-mil solid-state vapor barrier material. Our uniquely manufactured plastic will never separate and all surface area is12-mil thick due to the Crawl Space Ninja Vapor Barrier being solid and not thinly glued together sheets. 12-mil is as thick as it can be and still be flexible enough to install in crawl spaces. We have tested thicker plastic materials only to realize they would not bend as well as we needed them to.

Why Do Some Vapor Barriers Smell Like Cat Urine?

As mentioned on many of our YouTube Videos, moisture gets trapped in the dual-layer reinforced vapor barrier materials. The reinforced plastic is manufactured by gluing two pieces over the nylon string. Glues and adhesives eventually fail in a damp crawl space. These materials separate and moisture gets trapped inside. The wet nylon or reinforcement grows bacteria and fungus and that is when your crawl space and eventually your home starts to smell like cat urine. We eliminate this as an issue during crawl space encapsulation by not installing reinforced vapor barriers.

Today the internet is filled with more and more stories about an odor similar to cat urine after a crawl space encapsulation and waterproofing project has been performed. Please keep in mind there can be several reasons for odors in the crawl space and several solutions as well.

Many years ago we moved away from the industry-standard reinforced vapor barrier that most, if not all, crawl space encapsulation companies are using today. At first, it was just rumors that we were hearing about crawl spaces beginning to smell bad about three months after the encapsulation and waterproofing were installed.

We spoke to many professionals around the Southeast and discovered they were getting similar feedback of cat urine-like odors in the crawl space.

All the crawl spaces seemed to have one thing in common, they were encapsulated with a reinforced vapor barrier. Even with different manufacturers and thicknesses, the odor seemed to be an issue.

In order to address this potential problem from occurring with our crawl space repairs, we have moved to a single ply, non-reinforced vapor barrier.

Can Crawl Space Plastic Stop Radon?

Does a vapor barrier control radon levels? Not according to the information and situations we have found in the homes we have worked on in the past.

A crawl space vapor barrier is just that, VAPOR barrier. It is not an air barrier. Companies today are pushing vapor barriers as radon barriers and that simply is not true.

A vapor barrier is used in conjunction with a radon mitigation system. It is called sub-membrane depressurization. That does not make the plastic a radon barrier any more than concrete in a basement is a radon barrier.

Even if plastic was able to stop radon from entering the crawl space, it could still travel up cinder block walls or block pillars because cinder block does not stop radon either. Properly installing a sub-membrane radon mitigation system is the best practice for mitigating radon from your crawl space.

Many homeowners don't experience a radon problem until after the crawl space encapsulation system has been installed. Most crawl spaces are vented giving adequate air movement in order for the radon to escape naturally.


Should I Use an Underlayment?

Many crawl spaces have been used in the past as trash dumps so it is common to find debris like glass, cans, wood, roof shingles, siding, and even poured concrete. Some have gravel that can be very harsh to plastic.

Using an underlayment in the crawl space is a great way to protect your investment. An underlayment adds a layer of protection to the vapor barrier if you plan on storing items in the crawl space or if you have the need for plumbers, electricians, HVAC contractors, or other professionals to enter the space.

Utilizing a thick underlayment also gives the homeowner and contractor a bit of cushioning as they travel through the crawl space.

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Crawl Space Vapor Barrier Videos

Check out our latest crawl space vapor barrier videos by subscribing to our YouTube Channel. Arm yourself with the correct way to fix your crawl space to protect yourself, your family and your home.