Double-barrier approach for radon reduction in new construction

A double-barrier design with the space between the barriers having little resistance to gas flow is described for those parts of homes and buildings that interface with the soil or surficial rock to reduce soil-gas (radon) entry into structures. The outside or soil-side barrier interfaces with the soil. A barrier placed on the soil under the subslab aggregate is an important element in this design. This forms the outer barrier for the floor. The subslab aggregate forms a permeable layer, while the slab and caulking form the inner barrier. If hollow-block walls are used, the hollow space is connected to the subslab aggregate to form a small interconnected permeable volume between the inner and outer barriers that can be managed in the following ways to reduce soil-gas entry into the structure. 1. Sealed. 2. Passively vented to outdoor air. 3. Passively depressurized using an internal stack. 4. Actively depressurized. 5. Actively pressurized. In addition to basements with hollow-block walls, the double-barrier technique can be adapted to solid-wall, crawl-space, and slab-on-grade construction including various combinations. (orig.). (9 refs., 1 fig., 1 tab.)