Reducing Radon in New Construction of ANSI/AARST CCAH 2020 1 & 2 Family Dwellings and Townhouses 5 SECTION 302 ROUGH-IN COMPONENT INSTALLATION 302.1 Mitigation System Rough-In required. The installation of radon control rough-in components shall be required for all foundations and combination foundation types, including crawl space , basement and slab-on-grade. The installation shall be in accordance with Sections 302.3 through 701.5. Figure 302.1 illustrates the installations in these various foundations. Exception: The installation of radon control rough-in components is not required for: 1. garage slabs where there is no living space above the garage. 2. portions of buildings supported on foundation systems, such as piers, that do not have any enclosed areas between the earth and the building floor system. 302.2 Foundation area. As addressed in this standard, the foundation area shall be calculated from the inside perimeter dimensions of the foundation walls. 302.3 System Coverage Area Additional radon control system rough-Ins, with an independent exhaust pipe extending from the soil gas collection plenum to the roof shall be installed where the total foundation area exceeds the MaximumCoverage Area shown in Table 302.3 and each multiple thereof or as specified by a certified radon mitigation professional. TABLE 302.3 Exhaust Pipe Nominal Size Maximum Foundation Coverage Area Per System 3 inch [7.6 cm] 2,500 square feet (232 m 2 ) 4 inch [10.2 cm] 4,500 square feet (418 m 2 ) SECTION 401 SOIL GAS COLLECTION PLENUMS 401.1 Soil gas collection plenums. Foundation areas shall be constructed so as to create sealed soil gas collection plenums in accordance with Sections 402.1 through 404.1.6. Any groundwater control systems inside foundation areas shall be installed at the same elevation or lower so as to drain groundwater without closing off airflow through the soil gas collection plenums .