Vapor barriers are ideal for reducing/limiting moisture in the ground from evaporating and migrating up into the crawl space. This helps to prevent problems that arise when moisture condenses on cold surfaces, such as ductwork and wood. 

Unless you enjoy hearing phrases such as wood rot, mold and mildew, you’d be well-advised to use a vapor barrier. The takeaway? A vapor barrier is a good idea.

But what about vapor barriers? As in multiple barriers being used at the same time? Do you get extra credit if you use more?

Nope. 

In fact, I recently came across a crawl space in which two vapor barriers were installed in the crawl space. In my report, I wrote that the use of two vapor barriers actually causes problems because water can become entrapped between vapor barrier layers, prolonging evaporation time which can lead to stagnant water conditions. 

In other words, one barrier is more than enough.

Do you have questions or comments about vapor barriers, crawl spaces or home inspections in general? Go “All” in and tweet us (@AIHomeInspect).