Licensed & Insured. Crawl space Encapsulation and Mold Remediation

Is a Vapor Barrier Necessary in Your Crawlspace?

crawlspace vapor barrier nashville

Do you have a dirt crawlspace under your home? 

As a result, mold or wood rot may develop in the flooring and walls of your home. 

And no one likes to hear the phrases “moisture,” “mold,” or “rot” in their home.

Crawlspaces beneath older homes are typically ventilated, which means that small vents are provided to allow air to flow freely from inside to outside. 

These vents, in reality, do little to circulate air, so any moisture that manages to get under the house will remain there.

Ventilated crawlspaces are particularly harmful in humid regions, such as the Southeast and parts of the Northeast and Midwest of the United States. 

Mold, fungus, mildew, and bacteria thrive in the crawlspace because moisture-laden air condenses into water droplets on chilly pipes and concrete walls.

Fortunately, a vapor barrier may be properly installed to seal vented crawlspaces.

A Vapor Barrier’s Purpose

A sealed crawlspace is a preferable option for people whose homes are susceptible to humid weather. 

A vapor barrier surrounds a closed crawlspace to keep moisture out.

Even in the driest regions, crawlspace sealing can save energy. 

A research by Advanced Energy in Flagstaff, Arizona, found that sealing crawlspaces resulted in a 15% yearly energy reduction. 

Sealing your crawlspace is a good place to start if you want to reduce your energy use.

Polyethylene plastic is the most prevalent vapor barrier material. 

Reinforced materials and 10 mil barriers are even better.

Barriers to Vapor, Air, and Moisture

It’s possible that you’ve run into some muddled terminology when trying to figure out what kind of crawlspace barrier you require. 

Barriers to air, moisture, and vapor? 

To make things easier, here is a list of terms:

“Impermeable” refers to the permeability value of 0.1 perm or less for vapor barriers. 

They’re commonly used to keep moisture out of crawlspaces, basements, and walls and ceilings.

Similar to a vapor barrier in function, a moisture barrier 

You can use any of these terms in a sentence.

In order to keep moisture out of a building, air barriers must be used in conjunction with other measures, such as weatherstripping and caulking. 

insulation or siding can be used to produce self-contained air bubbles.

“Semi-impermeable” and “semi-permeable” vapor retarders are defined as materials with permeance ratings between 0.1 and 1.0 perm, respectively. 

However, vapor retarders are not as effective as vapor barriers in blocking moisture.

Installation of a Vapor Barrier

1. Calculate the required quantity of materials.

Determine the amount of poly sheeting you’ll need to cover your crawlspace before you begin installing it. 

Make sure you have enough cloth to cover the seams by at least 6-12 inches.

It’s best to use a 6-foot-wide roll for foundation walls, but a broader roll for the floor is necessary. 

Moisture can’t penetrate these liners because they’re extremely durable.

2. Determine what thickness is appropriate for your project.

A 6 mil (0.006-inch thick) poly sheeting is the most cost-effective option for a vapor barrier, but if the ground in your crawlspace is rocky, or if you want to use the space for storage or other purposes, you may want to choose a thicker liner. These liners are even more resistant to moisture.

3. Make certain that the poly is virgin.

Make certain that the polyethylene is virgin and formed from pure plastic beads. Regrind polyethylene contains imperfections and is made from recycled materials. While this is appropriate for some purposes, it is not appropriate for long-term crawlspace encapsulation. Learn more about the difference between virgin and regrind coffee. 

4. Obtain the necessary accessories

To seal seams and fix your vapor barrier to foundation walls, you’ll need the following tapes and fasteners:

Vapor tape is used to bind seams together, whereas Butyl tape is used to seal sheeting to foundation walls.

Christmas tree fasteners are used to attach sheets to foundation walls.

5. Wear appropriate safety equipment

The earth beneath a house can accumulate dangerous compounds over time, waiting to be disturbed by your presence. A decent respirator with a HEPA and charcoal filter is strongly advised. Also, ensure that you have:

  • Jumpsuit
  • Gloves
  • Kneepads
  • Eye protection is essential.
  • Head protection is essential.

6. Be prepared to get your hands dirty!

Do you have any further questions? Call 615-412-0172 to speak with one of our expertise specialists. We’re here to assist you!

Greg Lewis

Greg Lewis

Greg Lewis is the founder and CEO of Tier Restoration, a company dedicated to restoring the indoor environment of homes and businesses experiencing water damage, smoke damage, or mold contamination.

Greg has spent most of his life working in this industry in Nashville, Tennessee, in the 1970s, working in his father’s commercial cleaning business, in the 1980s and 1990s as a partner with his father in the Sears Carpet and Duct Cleaning franchise, then on his own since 2000.

Greg played his trumpet at Overton High School and the University of Tennessee, Chattanooga, and you can still find him playing throughout the Greater Nashville, Tennessee area.