What is the coverage requirement for vapor retarders to allow for ventilation reduction?

To allow for ventilation reduction, the requirement for vapor retarders is based on their coverage and effectiveness in controlling moisture movement. The correct choice specifies a minimum coverage of 1 in 1500 square feet. This level of coverage is important to ensure that the vapor retarder adequately limits the amount of moisture that can move through building materials, thus preventing potential issues associated with excessive humidity, such as mold growth and structural damage.

When a vapor retarder meets the required coverage ratio, it indicates that the building is equipped to manage moisture effectively, which in turn allows for a reduction in the amount of mechanical ventilation needed. This is crucial in energy-efficient building designs, where reducing ventilation can save energy costs while still maintaining healthy indoor air quality.

In contrast, other options suggest either insufficient coverage (like 1 in 1000 or 1 in 2000 sq ft) or specific installation methods (like being taped), which do not provide the same level of moisture control and might not meet code compliance for effective vapor retarder use. Therefore, choosing the minimum required coverage of 1 in 1500 square feet aligns with building codes and best practices, supporting ventilation reduction while ensuring building integrity and occupant health.