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Encapsulation vs Insulation: What’s the Difference?

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You probably know about the importance of a properly insulated home. Insulation can help prevent heat transfer between the outside and inside of your home. So if you have insulation in your crawl space, your home is protected and energy efficient, right? Not necessarily.

When it comes to crawl spaces, many environmental factors can affect the health and efficiency of the space. The primary culprit in an unhealthy crawl space is moisture. A moist, humid environment under your home can lead to mold, fungal growth, insect infestation, and decay. While insulation can help protect against heat transfer and frozen pipes, it does nothing to control moisture. In fact, it can actually aid in the growth of mold by providing a place for the spores to grow.

What is insulation, anyway?

Insulation is a thermal barrier made from materials such as fiberglass, foam, cellulose, and even wool. You can read more about common insulation types in this article, but the most common insulation in the Charlotte area is fiberglass batt. Fiberglass is made of extremely fine glass fibers spun together to form a porous, cloud-like material. It is applied to a paper backing to hold it in place and make it easier to handle. In a crawl space, batt is installed between the floor joists to protect against heat transfer between the air in the crawl space and the home’s floor. It will help with energy efficiency and protection against the cold, but it does not help with moisture or with air quality. That’s where encapsulation comes in.

What is encapsulation?

Encapsulation is the process of completely sealing the crawl space to prevent any outside air from getting in. When we encapsulate a crawl space, our crews place a heavy-duty layer of polyethylene material on the floor, up the walls, and around the support columns. Completely wrapping all of the exposed spaces ensures that moisture does not wick up from the ground into the columns and into the crawl space. If there is water intrusion or the crawl space is prone to standing water, a crawl space drainage system will be installed prior to encapsulation. If there is mold or fungal growth already in the crawl space, it will be removed before the space is encapsulated. Once the liner is applied, a dehumidifier is installed to keep the crawl space humidity at consistent levels to prevent moisture.

Is encapsulation better than insulation?

Though they may seem similar, there are far more advantages to encapsulation than insulation only. The primary benefit of encapsulation is moisture control. If the outside air is allowed to enter the crawl space in an area of the country where it is hot and humid, like Charlotte, all of that moisture in the air will be introduced into the crawl space. If the crawl space is sealed off from outside air, and a dehumidifier is used to control humidity levels, the encapsulated crawl space will be free from moisture and all of the side effects such as mold growth and insect damage. For that reason, the U.S. Department of Energy recommends encapsulated crawl spaces as ‘the best option in homes in hot and humid climates using proper moisture control and exterior drainage techniques’.

Another interesting fact that we have found is that crawl space encapsulation has amazing insulating properties, and a properly sealed, encapsulated crawl space does not need additional insulation. North Carolina building code specifies that a vented crawl space requires insulation between the floor joists or on the wall, but does insulation really provide any additional benefit in a sealed crawl space? We performed an independent study in 2019 to test our theory, which revealed some interesting data.

Using our 24/7/365 WiFi monitoring systems that we install in every crawl space that gets a dehumidifier or sump pump, we analyzed data from sealed crawl spaces and compared it to those with 2″ foam insulation in addition to being sealed. The study was conducted from 9/22/19 through 3/22/20. The results of the study show that the temperature in each crawl space was nearly identical and fluctuated no more than 8 degrees during the study window. Our conclusion? That an encapsulated crawl space with sealed vents does not need insulation.

In the readings above, the Buddy Elerby property on the left is from a crawl space that has all vents sealed with 2” foam board insulation on the interior of the foundation wall and a dehumidifier. The picture on the right labeled Philadelphia Church Rd is an older home, 60-70 years old, with no insulation, vents sealed, and a dehumidifier.

You can learn more about crawl space encapsulation and how much crawl space encapsulation costs in our Learning Hub. If you are interested in encapsulation or curious about the health of your crawl space, contact us to schedule a free, no-obligation consultation. We’re here to help!

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