Building Codes & Standards

Radon reducing new construction (RRNC) is the method of restricting radon entry into new homes, schools, workplaces and other buildings.

Building codes are the key policies that determine how homes and other buildings are designed and constructed. In some states, the state legislature, an executive branch agency, or an appointed board decide what’s in the building code for the entire state. In other states, local entities (counties, cities, towns, etc.) traditionally decide what’s in the building code. Eleven states (CT IL ME MD MA MI MN NE NJ OR WA) require radon-reducing construction methods. Since homes with high radon have been found in every zone, CT IL ME and MN protect homes in all areas; other states only require RRNC in homes in Zone 1 counties or another subset. Six states (IL ME MN NE NJ WA) cover all types of homes; four states (CT MA MD MI) limit protection to one and two family homes and townhouses; one state (OR) covers the same plus apartments.

The International Code Council (ICC) is the framework for building code policy in the US. Its model new construction codes are widely adopted by states and local jurisdictions. The table below presents the ICC codes and their radon-related code provisions.

Radon stakeholders have worked continuously to improve the ICC IRC Radon Appendix: 

2025 Report: IEA, American Lung Association, Conference of Radiation Control Program Directors, US Environmental Protection Agency, and National Center for Healthy Housing submitted code change proposals and comments to the International Code Council to improve the Radon Appendix (known as Appendix F until 2021, Appendix AF in 2021 and Appendix BE beginning in 2024) in the International Residential Code. One proposal, led by EPA, would eliminate the limitation of the use of Appendix F to Zone 1 and delete the EPA radon map and county list. Another proposal involved permitting adherence to the ANSI-AARST RRNC standard as an alternative pathway for compliance with the protocol contained in the Radon Appendix.  Technical proposals called for connecting 5 feet of perforated pipe to each side of the Tee fitting under a slab or vapor barrier and centering pipe in an unobstructed cylindrical space in the attic for fan installation except where an electrical supply is provided on the roof or other accessible area.  The IRC-B Committee heard the proposals at an in-person meeting in Orlando May 1, and approved permitting adherence to the ANSI-AARST RRNC standard as an alternative pathway for compliance with the protocol contained in the Radon Appendix. Public comments seeking to further the remaining three proposals were submitted in July for consideration by the same committee. During its second hearing October 23 Cleveland, the IRC-B Committee approved the remaining three proposals, removing the EPA map and county list, requiring 4.5 feet of perforated pipe on each side of the Tee under a slab or vapor barrier, and requiring that the pipe in the attic be located in an unobstructed cylindrical space to allow for fan installation.

2022 Report: IEA, American Lung Association, CRCPD, EPA, and National Center for Healthy Housing submitted code change proposals and comments to the International Code Council to attempt (once again) to improve Appendix F. Technical proposals call for connecting perforated pipe or geotextile matting to the tee fitting under the slab; centering the pipe in an unobstructed cylindrical space in the attic for fan installation except where an electrical supply is provided on the roof or other accessible area; connecting perforated pipe or geotextile matting to the tee fitting under the membrane or connecting it to the interior drain tile system; specifying ASTM E1745 Class A poly to be consistent with another section of the IRC; and allowing an exception from placing aggregate or sand where geotextile drain matting is installed on well-drained or sand-gravel mixture that meets Group 1 classification. A sixth proposal, led by EPA, would eliminate the limitation of the use of Appendix F to Zone 1 and delete the EPA radon map and county list. The IRC Committee heard the proposals at an in-person meeting in Rochester NY in April, and approved the proposals for poly consistent with the IRC and for exempting geotextile matting on Group 1 soils. Several public comments seeking to further the above proposals were submitted in July for consideration by the ICC membership. During the public comment hearing September 17 in Louisville KY, only the proposal to amend the language for the aggregate/sand exception was approved. 

2019 Report: Appendix F of the IRC was the focus of collaborative radon risk reduction advocacy by CRCPD, EPA, and IEA during 2019. At the final action hearing and during online voting, after considering the three organizations’ comments as well as input from others, voting members of the ICC rejected sidewall venting as an option to rooftop venting and agreed to add a testing requirement to Appendix F. Effective in the 2021 codes, radon control installed in new one- and two-family homes in accordance with IRC Appendix F will be considered incomplete unless a radon test provided to the code official reports that the radon level is below 4 pCi/L.

The Consortium on National Radon Standards is the source of new and actively maintained consensus radon standards. ANSI-AARST CCAH is the core standard for new construction of one and two-family dwellings and town-homes; ANSI-AARST RRNC is the new construction standard for one and two-family dwellings and town-homes that does not include activation, similar to the IRC Appendix F. CC-1000 is the ANSI-AARST standard for RRNC for large buildings including multifamily dwellings, schools and workplaces.

Continuously maintained building standards that contain RRNC provisions include the American Society of Heating, Refrigeration and Air-conditioning Engineers’ (ASHRAE) Standard 189.1 for the Design of High Performance Green Buildings, the US EPA’s Indoor Air Plus Protocol, the National Association of Home Builders’ Green Building Standard, and the US Green Building Council’s LEED.