Franklin County
Franklin County is classified as EPA Radon Zone 2, indicating moderate radon potential. The predicted average indoor radon screening level is between 2 and 4 pCi/L. While below the EPA action level, many individual homes in Zone 2 areas test above 4 pCi/L. The EPA recommends testing all homes regardless of zone.
What This Means for Franklin County
Should You Test?
Yes. While Zone 2 has moderate predicted levels, many individual homes still test above 4 pCi/L. Home-specific factors like foundation type, soil permeability, and ventilation matter as much as the zone classification. A $15–$30 short-term test kit is the easiest way to find out.
Real Estate
Consider requesting a radon test during the home inspection process. Many real estate professionals in Missouri include radon testing as standard practice. If levels are elevated, mitigation systems are effective and relatively affordable ($800–$2,500).
New Construction
The EPA recommends considering radon-resistant new construction (RRNC) techniques in Zone 2 areas. These features add $350–$500 to construction costs and include a sub-slab gas collection layer, vapor barrier, sealed cracks, and a vent pipe to the roof. Much cheaper to install during construction than to retrofit.