Conditioned crawl spaces perform better than vented crawl spaces in terms of safety, health, comfort, durability and energy consumption. Conditioned crawl spaces also do not cost more to construct than vented crawl spaces. Existing vented crawl spaces are experiencing serious moisture and mold problems and are costing builders and homeowners significant resources to repair. Despite the obvious problems with existing vented crawl spaces and the obvious benefits of conditioned crawl spaces there is not a significant trend towards the construction of conditioned crawl spaces. One of the reasons typically cited by builders and designers is “the code does not allow me to build unvented crawl spaces.” This is both generally correct and misleading. The model codes do not allow the construction of “unvented” crawl spaces – except in very limited circumstances, but they do allow the construction of “conditioned” crawl spaces. The distinction is important and necessary. Four conditioned crawl spaces were constructed and monitored over a 12-month period. The data is presented and used to support the current code requirements for the construction of conditioned crawl spaces.

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