Installing a Vapor Barrier in Your Basement Walls

  • 50-500 hours
  • Intermediate
  • 4-8
What You'll Need
Seam tape
Vapor barrier
Measuring tape

Basement walls are susceptible to water damage because they are built underground. A vapor barrier can be installed to give your basement walls some extra protection from this danger. Water damage can be very costly to repair because it can damage anything in your home.

Installing a vapor barrier in your basement walls is actually very easy as long as you have the right tools and enough time to complete the job. If your basement walls are damp and moldy, vapor barriers may be an effective way to prevent water from being able to seep inside your house. Follow these steps to install a basement vapor barrier.

Choosing a Vapor Barrier

Choose a vapor barrier that can be installed on your wall. Although there are some weatherproofing materials that can be applied with a paintbrush, a vapor barrier is a rubber-based material that is fixed onto the wall. These vapor barriers are normally delivered in roll form. They can be unrolled and positioned onto the wall.

Preparing the Wall

If there is any water on the wall, remove it. The wall must be completely dry during installation. If there are any cracks, repair them. If there are any gaps between window frames and the wall, use caulking to fill them.


Measure the size of the walls that need vapor barriers. Ensure that the measurements are accurate so that the wall is fully protected.

Marking the Vapor Barrier

Once you have your measurements, mark them on the vapor barrier with a pencil. The material can then be cut using either a craft knife or scissors. Don't cause any damage to the rest of the material. When marking the vapor barrier, ensure that the material passes 2-inches below the bottom of your basement.

Wherever there is a joint, the vapor barriers should be overlapped. Ensure that the measurements are accurately marked so that the vapor barrier will be able to provide your wall with plenty of protection from the elements.

Fixing the Vapor Barrier

Use a staple gun or nails to hold the vapor barrier in place on the wall. Wherever there is a seam, you should use specialist tape to prevent water from becoming a problem. It's important to use specialist tape which offers the right protection. Don't apply too many nails, as doing so will weaken the vapor barrier. One nail every 2 to 3 feet should be plenty.

Finishing Your Wall

Once you've fitted the vapor barrier to the wall, you need to finish it within 30 days. If you leave it too long, then you are risking causing it damage. The longer you leave the wall without protection, the more likely the vapor barrier will be compromised.