The Importance of Crawl Space Vapor Barriers

Crawl Space Vapor Barrier

Vapor barriers can encapsulate your crawl space and establish a clean, dry area below your home. They do so by sealing out exterior air, groundwater, and precipitation, all of which contribute to the most common crawl space issues. Maintaining a dry crawl space can decrease your energy bills, prevent rot from afflicting your structure, and protect your home’s inhabitants. Reach out to your local waterproofing service provider for crawl space vapor barrier installation and enjoy a safe, healthy, and sustainable home.


NV Waterproofing & Foundation Repair offers crawl space services, basement waterproofing, and foundation repair. We are a dedicated provider that delivers thorough craftsmanship, respect, and care. Discover our innovative solutions for improving your home by calling our office at 1-855-649-7594 and scheduling your free, no-obligation cost estimate.


Below, we outline what makes crawl space vapor barriers so important:

Seal Out Outside Air

As we all learned in science class, water moves through the air as humidity. For every degree (Fahrenheit) that the air temperature decreases, the relative humidity rises by 2.2%. Moreover, the difference between the outdoor temperature and that of your crawl space can exceed 20 degrees Fahrenheit.


Therefore, cool outdoor air entering a warm crawl space will jack up its relative humidity. The opposite reaction occurs if warm outdoor air enters a cool crawl space. So, drafty crawl spaces tend to struggle with high relative humidity even in climates with moderate outdoor humidity.


Once trapped in your crawl space, humidity wreaks havoc. It rots girding and floor joists and encourages mold growth, jeopardizing your home’s structural integrity. Humidity also makes the space a welcoming environment for bugs and rodents. Additionally, 50% of the air on your first floor comes from your crawl space. That humid air requires extra energy to heat and cool, increasing your energy bill by 15-25%.


To seal out humidity, our technicians close all crawl space vents with plastic CleanSpace vent covers and airtight gasket fasteners. We also recommend replacing wooden crawl space doors with plastic ones, which do not rot or warp. Finally, we can seal all leaks for exterior air. These often occur where your foundation meets the sill of your crawl space walls or around pipes.

Seal Out Ground Moisture & Rainwater

Crawl space dirt floors not only retain moisture from the earth but also collect rainwater that enters the space. As that moisture evaporates, its vapor moves up into your home to create mold, poor air quality, and a slew of other problems.


Water vapor can also travel through concrete floors because concrete is porous. Even worse, concrete floors without proper drainage can collect standing water. With nowhere to go, that water will evaporate up into your home.


To seal out ground and rainwater in dirt-floored crawl spaces, we install CleanSpace vapor barriers. These thick, plastic liners—which cover the walls and floor—resemble pool liners, though they contain polyester reinforcement for added strength. In crawl spaces with concrete floors, we install dimpled polyethylene drainage mats. This material creates a space below the plastic seal through which water can drain into a TripleSafe sump pump.

Combat the Stack Effect

Water vapor barriers also seal help combat the stack effect, which refers to the movement of hot air through a building. Recall that half of your first floor’s air comes from your crawl space. That air mixes with the temperature-controlled air from your furnace, and it all rises until it escapes through windows, air vents, and cracks in the roof.


As the warm air escapes, it reduces pressure at the bottom of your home–specifically, your crawl space (if it is vented). This effect pulls air into your home to be heated or cooled, thus further increasing your energy bill. Yet a vapor barrier seals your crawl space against the stack effect’s suction.

NV Waterproofing: Professional Crawl Space Vapor Barrier Installation

The Importance of Crawl Space Vapor Barriers - Image 2

Protect your home from moisture with crawl space vapor barrier installation from NV Waterproofing. We are a trusted service provider and a winner of Angie’s List Super Service Award multiple years in a row. Our repair and installation services create more comfortable and durable homes for our customers. Call us today at 1-855-649-7594 for a free cost estimate.

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NV Waterproofing & Foundation Repair
12200 Livingston Rd
Manassas, VA 20109
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