In a wall where brick is on the outside and sheetrock is on the inside, where should the vapor barrier be installed?

The correct placement of a vapor barrier in a wall assembly with brick on the exterior and sheetrock on the interior is behind the sheetrock, which is situated on the inside of the insulation. This placement is crucial for several reasons.

First, the primary function of a vapor barrier is to prevent moisture from migrating into the wall assembly from the interior living space. If moisture penetrates, it can condense within the wall, leading to mold growth and structural damage. By installing the vapor barrier behind the sheetrock, it effectively stops moisture generated from activities like cooking, bathing, and breathing inside the home from moving into the wall cavity.

Additionally, placing the vapor barrier on the interior side allows for the insulation to perform effectively. Insulation works best when not saturated; hence, keeping the insulation dry is critical for thermal performance. If the barrier were placed on the exterior side of the insulation or between the insulation and the brick, it could trap moisture within the wall assembly, leading to potential issues.

Overall, the correct position of the vapor barrier behind the sheetrock aligns with best practices in construction, ensuring moisture control and maintaining the integrity of the wall system.