Homeowners often ask if a vapor barrier is necessary for optimizing attic insulation and protecting their homes from moisture-related damage. The answer, however, isn’t one-size-fits-all.

Cover the floor and foundation walls with a plastic vapor barrier, and use a dehumidifier to remove remaining moisture from the air. All of these steps work together to control moisture levels.

The barrier typically comes in the form of sheets of plastic or foil-backed fiberglass insulation and is used during insulation installation to block vapor transmission. In many cases, vapor ...