What is the purpose of a home's vapor barrier?

The purpose of a home's vapor barrier is fundamentally to control humidity and prevent moisture intrusion in the building envelope. By doing so, it helps to maintain a stable and healthy indoor environment. Vapor barriers are usually installed in areas such as basements, crawl spaces, and attics, where moisture can accumulate and lead to problems such as mold growth, wood rot, and structural deterioration.

When vapor barriers are properly installed, they prevent water vapor from passing through walls and ceilings, which is crucial in humid climates. This control of humidity not only enhances the comfort of living spaces but also protects the integrity of building materials and finishes. Therefore, the function of a vapor barrier is central to safeguarding a home from the detrimental effects of moisture.