Components of Closed Crawl Spaces

Until around 75 years ago, houses in the Coastal South were built out of solid lumber components of stud walls, diagonal sheathing, wood siding, and the interior was finished with plaster. When the walls got wet they were able to dry because there was no insulation and plentiful leaks to let air circulate in and out of the walls. There was not a problem with mold because solid lumber is not eaten by mold. Without air-conditioning, high ceilings, porches and cross ventilation contributed to making the house bearable in a hot, humid climate. This sounds like a good system except thermal comfort is almost impossible to achieve in a leaky, un-insulated structure .

Closed Crawl Spaces

If you have had second thoughts about having a closed crawl space in the hot, humid South..think again. The North Carolina research company Advanced Energy "has confirmed over the long term...that outside air contains more water vapor than the air in the crawl space during the warm seasons, and has no potential to dry the crawl space. Instead, the outside air ends up contributing water vapor to the crawl space." Thereby, vented crawl spaces support mold growth in a hot, humid climate. Advanced Energy's research on closed crawl spaces compared to vented crawl spaces showed that "closed crawl spaces consistently outperformed the wall-vented crawl spaces in terms of both moisture control and energy use." Learn more about closed crawl spaces here http://www.crawlspaces.org/