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Crawl Space Vapor Barrier

The vapor barrier is one of the most important aspects to making sure your crawl space is dry, clean, healthy and efficient. Installing the wrong type of vapor barrier can cause cat urine type odors to occur. Installing the vapor barrier incorrectly can allow moisture intrusion. Make sure you choose the right vapor barrier for your crawl space.

Free Vapor Barrier Assessment
  • PLEASE NOTE: Only submit this form if you are located in the East Tennessee area including Knoxville and Chattanooga -- we can only perform assessments and work in these areas. If you are outside of this area, look for a reputable company near you, or consider doing the work yourself by visiting our DIY Store: https://crawlspaceninja.com/diy

"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 dehu running as needed down there. Our furnace/AC and gas water heater are all in the crawl space as well. So we have those venting out 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. Read more.

Jeff Weikert, Atlanta, GA

Image of cat to portray vapor barrier cat urine odor

Vapor Barrier Odors

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

Crawl space vapor barrier - About three years ago we moved away from the industry standard reinforced vapor barrier that most if not all crawl space repair 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 waterproofing was performed.

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.

The results have been fantastic. We have received ZERO complaints of any cat urine type odors.

radon vapor barrier

Radon Vapor Barrier

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 vapor barrier a radon barrier no 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.

Make sure the crawl space professional you hire is properly trained in EPA standards of air flow while controlling humidity.

Image of Crawl Space vapor barrier underlayment

Vapor Barrier 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 vapor barriers.

Using a crawl space vapor barrier underlayment is a great way to protect your investment. Underlayments add 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.

Crawl Space Vapor Barrier DIY

If you are like many homeowners and would like to perform the vapor barrier installation yourself, we are here to help.

We are now making our exclusive Crawl Space Ninja Vapor Barrier available to those wanting to tackle the job themselves. Just keep in mind, it is not as easy as most people think.

To learn more about vapor barrier pricing please click here.

Free Vapor Barrier Assessment