Saito shares, ‘Manual crawl space vents, which are usually $15 to $25 per unit, run lower than the automatic crawl space vents like this Master Flow Automatic Foundation Vent from Home Depot ...

For homes that have crawl spaces, as much as 50% of the air inside your house might originate in the crawl space. It seeps upward through the floor into the house.

Crawl space encapsulation might provide a positive ROI if the buyer understands the benefits, but it is typically a preventative maintenance project that makes for a safer home. More from U.S. News ...