Most crawlspaces are vented to the outdoors, but over the past decade, encapsulating the crawlspace (as shown in the first photo) has gained favor among builders of green and energy-efficient homes. It's often seen as the best way to eliminate the moisture problems that can result from vented crawlspaces. But what do you do about the air down there?Before we address that question, let me point out that encapsulated crawlspaces are great for humid climates such as those in the Southeastern U.S. In a dry climate, however, it may not be worth the cost to encapsulate. So do what's most...

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