How thick should your vapor barrier be in crawlspaces?

The correct thickness of a vapor barrier in crawlspaces is typically around 4-6 mm. This thickness is effective in preventing moisture from rising through the ground and into the crawlspace, which is crucial for protecting the integrity of the building structure and maintaining a healthy indoor environment.

A vapor barrier serves to impede the movement of water vapor, and a thickness of 4-6 mm strikes the right balance between durability and moisture control. Thinner barriers may not provide sufficient protection against moisture intrusion, ultimately leading to potential issues like mold growth or erosion of materials. On the other hand, thicker barriers beyond 6 mm can sometimes be unnecessary for typical residential settings, and could become challenging to install properly without creating air pockets that defeat the purpose of a vapor barrier.

This is why a thickness of 4-6 mm is generally recommended for effective moisture management in crawlspaces.