But I Never Go Down There, So Why Should I Care?

If you care about how much you pay for heating and cooling, then you care about your crawl space. If you care about your home rotting, or mold, allergies, or asthma, then you care about your crawl space. IF you care about the comfort of your home, cold floors, drafts, and how your home smells, then you care about your crawl space. If you care about the resale value, then you care about your crawl space. You can't get away from it. Your home is one system. It operates as a system. You can't have one part that is sick and another part that is healthy. You can't rationalize that since you never go in the crawl space you aren't affected by it. Why? Simple. Air mixing. The crawl space air is bad. It is damp. It is cold if it's winter. It is full of mold spores. It smells. And this crawl space air is in your building envelope. 

Credit- Lawrence Janesky