How to Install a Vapor Barrier

Lead Image
  • 3-24 hours
  • Beginner
  • $60-120
What You'll Need
Seam tape
Caulk gun
Vapor barrier roll
Staple gun

A vapor barrier can protect the frame of your home from water damage. The barrier is designed to block vapor from accumulating and provides an outlet for the water. A vapor barrier can also increase your home's energy efficiency. With a little effort, you can install this helpful device yourself.

Step 1 - Picking a Vapor Barrier

While plain plastic sheeting is commonly used to make vapor barriers, these traditional poly barriers will allow water and vapor to pass.

If you want a high-quality barrier that will actually your home's frame from rot and mold, you need to invest in a barrier with new technology. You can generally find great vapor barriers at any store that sells concrete supplies.

Step 2 - Choose a Location

There are many places in your home that a vapor barrier could be beneficial. Under the foundation is the most important place. If your home has already been built, such an upgrade is impossible. If your home is being built, have your contractor show you the barrier they plan on using.

Attics and crawlspaces are also prime candidates for vapor barriers. Humidity is more apt to accumulate in the walls of these areas, spurring mildew, mold, and rot. Not only can these growths cause a health problem, but they can also cause severe damage to the structure of your home.

If you have a wine cellar or basement, add a vapor barrier there too. Too much humidity in a wine cellar can damage the corks and ruin the wine.

Step 3 - Install the Barrier

If water has already accumulated on the surface, clean it before you start the installation process. The area on which you are installing the vapor barrier should be clean and dry. You can use caulk to fill in any gaps or cracks.

Record the wall measurements. Add 2 inches to allow enough of the barrier to stop water from entering as it rolls towards the floor. All of the joints should have a double layer of barrier for a total thickness of 4 inches.

Roll the barrier onto the wall where you’ve marked the measurements. Use your staple gun to attach the barrier. Don’t be afraid to over-staple.

Use your tape to seal the seams of the vapor barrier. Using tape that is specially designed for this purpose. Using other kinds of tape will compromise the waterproof seal and render the barrier useless. To be extra certain, use a caulk gun to place caulk material around the tape to double-seal the barrier.

Finish the wall within a month of installing the barrier to prevent damage to the surface and protect the vapor barrier.