DeWitt, principal of RLC Engineering, LLC, Clemson, S.C., pointed out that in more humid climates, venting the attic and crawl space could spell disaster. "Code says to vent the heck out of them," De Witt said. "If that doesn't work, vent some more. However, once we get condensation in ductwork, it is self-propagating."
In a paper he authored, DeWitt re-counted, "At an Affordable Comfort meeting that I recently attended, a speaker from Canada said that venting crawl spaces in the southeastern U.S. was lunacy. I have to agree."