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Why Do Crawl Spaces Have Vapor Barriers?

Let's start with an example. You have two pieces of wood, you put one out in your garden and the other in your closet, which one will rot away faster? Easy right? Obviously the one in the closet will last much longer. So when you leave the wood under your house exposed to moisture, mold and rot can take over. 

When we are talking about the wood that supports the structural integrity of your home, it's kind of a big deal. So, it's essential that we pay attention to all the key factors in keeping the structure of your home in good health. 

In most humid and rainy climates- like here in Western Kentucky- it's almost impossible to keep at least a little water from seeping through your foundation and into your crawlspace. Keeping that in mind, a quality vapor barrier, aka moisture barrier, that has been professionally installed works wonders in eliminating most of the moisture beneath your home. Before installing a vapor barrier it is important to make sure you have only moist soil -at most- in your crawl space and not standing water, which can indicate other problems that will need to be addressed first.

Once a vapor barrier is installed, that last bit of moisture that comes up from the soil is now blocked from rising up into the air of the crawl space. Any moisture left will now just hit that plastic barrier and stay underneath, protecting your homes structure and keeping your crawl space nice and dry.

As an added benefit, a good vapor barrier also prevents harmful radon gasses from emerging from the soil and into the air you breathe in your home. Radon is a natural gas that comes from the earth and can enter through cracks or holes in your foundation. 

Home owners don't often get in their crawl space, but pest control, HVAC, and plumbers are often down there. You need to make sure when they are, your vapor barrier is staked down properly -especially in high traffic areas- and doesn't bunch up while they crawl around. A basic 6mm plastic barrier should last 7-10 years if properly installed.

While there can be multiple factors to be addressed when looking at the state of your crawlspace, ultimately a properly installed vapor barrier will do the most to ensure the structure of your home lasts for years to come.


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