Guides

Short, sourced answers to the questions behind the numbers.

Radon and Crawl Spaces: EPA Zones and What They MeanWhat EPA's county radon zones predict, what they do not, and why encapsulating a crawl space and venting radon share most of their parts. Reading Your County Soil Survey for a Crawl SpaceDrainage class, hydrologic group, water-table depth and flooding: the four soil-survey fields that matter under a house, in plain terms. Vented vs Unvented Crawl Space: What R408 RequiresWhat the building code requires for a vented crawl space and for a sealed one, why wet-soil counties push toward sealing, and what each costs you in parts.