A Crawl Space Vapor Barrier can Control Moisture and Prevent Costly Home Repairs

Homeowners probably know more about rocket science than about their crawl space. This is because the crawl space is not at all considered as a living space and is therefore perceived to be an unimportant part of the house. What most homeowners do not realize is that the said part of the home plays a crucial role in keeping any house or building safe, sturdy and even energy efficient.

The crawl space in itself is made of a few components. Those components are vital in keeping that area of the home intact and protected against destructive elements like water and moisture. One of the key components in an ideal crawl space is the vapor barrier. The crawl space vapor barrier is used mainly in controlling the movement of water vapor of moisture. It should not be confused with a vapor retarder which is basically used in stopping water in its liquid form while controlling very limited amounts of water vapor.

water_droplet2Vapor Barrier and Moisture Problems

One of the words which is most closely associated with crawl space is: moisture. There’s a reason for that. Crawl spaces are specifically designed to prevent moisture from seeping and building up under the structure. With all the unwanted elements that come with the presence of excessive amounts of moisture, like molds, mildew and pests, a crawl space should always be kept secure and functional using the right components. This is where a vapor barrier plays an important role.

A vapor barrier, sometimes called a moisture barrier, is an impermeable plastic material which is designed to significantly reduce the amount of moisture or vapor allowed to enter a certain area such as crawl spaces and basements. To be more specific, vapor barriers are used in guarding spaces from elements like mold, mildew, fungi, possible allergens, wood rot and radon while preventing heat loss at the same time. A good crawl space vapor barrier  will keep such elements from migrating or settling inside or within the home, thus, making the overall environment of the living space healthier.

Installing a Crawl Space Vapor Barrier

Vapor or moisture barriers, as mentioned earlier, play an important role in safeguarding the crawl space from moisture and its effects. Thus, proper installation is required. The following materials are usually needed in installing vapor barriers in the crawl space:

  • Rigid insulation
  • 6-mil plastic
  • 1-1/2 in. rigid insulation
  • Tape
  • Treated 1x4s
  • Caulk
  • Landscape fabric stakes

Also, basic tools like tape measure, hammer, caulk gun and utility knife are needed.

Builders and professional crawl space insulators usually install vapor barriers in 4 basic steps.

  1. First, a drain must be created to prevent rainwater or melting snow from entering the under the house. Also, sloping the soil away from the house is highly recommended.
  2. The vapor barrier is installed by covering the dirt or the crawl space ground all the way up to six inches of the crawl space wall. Areas where the plastic vapor barrier overlaps must be taped, especially the seams. The landscape fabric stakes must be used to keep the plastic sheet in place.
  3. Once the vapor barrier is already in place, the foundation walls which remain exposed must be covered with insulation along with the rim joists which should be secured using caulk. Doing so will prevent moisture leaks.
  4. Lastly, the interior of the foundation should be capped with a layer of plastic (6 mil) and galvanized flashing to further prevent moisture. This will also protect the space from termites and the infestation of other insects and pests.

moisturebloc_vapor_barrierHomeowners should keep in mind that installing a crawl space vapor barrier is a job best performed by professionals. There are a lot of firms and small construction businesses that specialize in crawl space finishing systems. You can always search the internet or check out your local yellow pages to find people who can do the job in the homeowner’s behalf.