A newly built ventilated crawl space with a vapor retarder is REQUIRED to have how much net ventilation opening for every 150 square feet of crawl space?

For a newly built ventilated crawl space that includes a vapor retarder, the requirement is to have one square foot of net ventilation opening for every 150 square feet of crawl space area. This standard is based on ensuring adequate airflow to prevent moisture accumulation, which can lead to mold, timber decay, and other issues that affect the integrity of the structure.

Proper ventilation in a crawl space is critical as it helps to control humidity levels and allows any excess moisture to dissipate. The one square foot requirement per 150 square feet is a guideline rooted in building codes and best practices for maintaining a dry, healthy environment in the crawl space.

The other options suggesting higher ventilation ratios would not align with the standard building codes for a newly constructed ventilated crawl space. Adequate ventilation is important, but excessive requirements could lead to unnecessary costs and complexity in construction without providing significant additional benefits.