What is the purpose of a vapor barrier?

The primary purpose of a vapor barrier is to prevent moisture from passing through walls, ceilings, or floors into building materials. This is vital in maintaining the integrity of the structure, as excess moisture can lead to issues such as mold growth, wood rot, and damage to insulation. By acting as a barrier to moisture, it helps maintain the desired indoor conditions and protects building materials from decay, thereby extending the lifespan of the structure.

In various building applications, especially in climates where temperature fluctuations are common, vapor barriers are strategically installed to minimize moisture migration. This is important not just for the longevity of the building materials, but also for the health and comfort of the occupants.