What should be done to seams between sheets of vapor retarder?

The correct approach to treating seams between sheets of vapor retarder is to tape and seal them. This is essential because vapor retarders are designed to limit the movement of moisture and prevent condensation within walls, ceilings, and floors, which can lead to mold growth and structural damage.

When seams are left unsealed, there can be gaps that allow moisture to pass through, undermining the effectiveness of the vapor retarder. By taping and sealing the seams, you create a continuous barrier that enhances the vapor retarder’s performance, ensuring that it effectively reduces moisture transfer.

This measure also contributes to the overall energy efficiency of a building by preventing air leaks and maintaining indoor comfort levels. In areas where climate control is critical, properly sealing the seams helps maintain the integrity of insulation and reduces energy costs in heating and cooling.

Other options, such as leaving seams unsealed, painting them, or covering with a plastic sheet, do not provide the necessary airtight and watertight seals that are crucial in the function of a vapor retarder. These alternatives could compromise the moisture barrier and permit air and moisture infiltration, which defeats the purpose of using a vapor retarder in the first place.