When to close crawl space vents in NC?

Crawl space vents should always remain closed, as they allow outside air, water, and pests inside to wreak havoc and contribute to high relative humidity and other issues. Properly closing and sealing crawl space vents is part of Tar Heel Basement Systems’ comprehensive crawl space encapsulation process. Along with other waterproofing and encapsulation solutions, this helps create an isolated and conditioned environment.