CC-1000_2018

CC-1000 Companion Guidance (1-2018) CC-1000 Companion Guidance CG Page of 12 Informational 1 UNDERSTANDING SOIL GAS ENTRY AND CONTROL Soil gas is driven into a building wherever enclosed airspaces are under negative pressure relative to adjoining soil. Soil can contain hazardous gas that is often undetectable prior to construction. As it is for outside air that enters a building, soil gas is pressure-driven into a building through even the smallest unidentifiable of openings. Constructed foundations naturally confine soil gas under the entire expanse of foundation floors. The foundation enclosure is both: a) an environment where hazardous gas can cumulate to high concentrations under and around the building. Therefore, small volumes of soil gas entering a building can result in a significant indoor hazard; and b) a large expanse of soil that is under the influence of air pressures within the building. When the pathway within soil poses relatively little resistance to soil air movement, high volumes of mildly concentrated soil gas can also result in a significant indoor hazard. The stronger the negative pressure is within a building relative to adjoining soil, the larger the expanse of soil that is influenced by building pressures. The path of entry into the building is the cumulated size of all identifiable and unidentifiable openings. USING THE CC-1000 COMPANION GUIDANCE There are no mandatory requirements within this Companion Guidance document. As per CC-1000: Sections 1 - 4 Overview for building designs relative design of soil gas control systems Sections 5 - 7 Detailed specifications where the building meets the soil Sections 8 - 9 Vent pipe and exhaust components Sections 10 - 13 Completing systems, evaluation of heating and cooling system air pressures, operation and maintenance, monitoring and application for chemical vapor intrusion Annexes Optional inspections and a table for estimating fan specifications. STEP-BY-STEP PROCEDURES FOR DESIGNERS AND INSTALLER TEAMS Step Teams Task 1. Building design team Design systems (Include a radon/soil gas professional on the design team) 2. Grading/soil Verify subgrade resistance to permeability - add closure if necessary 3. Flatwork or drainage Close the sides of foundation walls below grade 4. Plumbing or drainage Place inlet pipe or inlet piping network ducts 5. Grading Add gas permeable layer Inspect for compliance—Prior to closure over soil by concrete or soil gas retarders 6. Flatwork Apply membrane over gas permeable layer and soil in crawl spaces 7. Flatwork If a slab, cast the slab with gasket closure at concrete joints 8. Flatwork or drainage Close edges and all sizable openings in slabs and crawl space membranes Inspect for compliance—Prior to completing indoor finishings (in ground-contact areas) 9. Qualified professional Conduct pressure field extension evaluation to ensure adequacy 10. Plumbing and electrical Extend exhaust piping to the roof and provide for fan Inspect for compliance — Prior to completion of indoor finishings (where pipe is installed)