How do you keep moisture out of your house? It might seem like an impossible task, especially if you live in an area with high humidity or a lot of rain, but there is something that was engineered specifically for that task. What is it? Vapor barriers. A vapor barrier is often made out of a plastic called polyethylene, but sometimes a certain type of paper is used, and other times a paint. These all serve the purpose of blocking out unwanted moisture from your home. Using a paint as a vapor barrier can be very cost effective, since you most likely would paint that surface anyway. It is important to ensure complete coverage for the vapor barrier to function properly. If the paint gets scratched off for some reason, it needs to be reapplied.
The plastic sheets are a little tricky to install, since it is easy to rip, especially if you use the thinnest variety. If you know that you will be installing it on a rough surface, it is worth to spend the extra money on a more solid version that isn’t as likely to rip.