Vents are sealed with vent covers installed outside. The building code required these vents when your home was built. The building code was wrong and made your problem worse by letting in hot, humid air in the summer, which causes condensation and rot and mold. In the winter these vents let in freezing cold air, making your floors upstairs cold and wasting energy. The building codes are now changing, and in the future vented dirt crawl spaces will be a thing of the past.
Before: Vent Open 
After: Sealed With Vent Cover |
