Radon testing must follow the procedures established by the American Association of Radon Scientists and Technologists, Protocol for Conducting Radon and Radon Decay Product Measurements in Multifamily Buildings Section III (ANSI-AARST MAMF-2010), with the exception that at least 25 percent of the ground level apartment units will be tested. The threshold for unacceptability is 4.0 pCi/L based on the first test and any subsequent tests. Residents must be informed that their apartment will be tested for radon, and also before and after any mitigation procedures are completed. For new construction, the new residents must be informed that radon mitigation activities were performed on the site. The Radon Professional will assure that mitigation activities conform to the ASTM standards for existing buildings and new construction. High-rise buildings are currently included in the mitigation standard but HUD is drafting a new standard for high-rise residential buildings.
For properties that are new construction or significant rehabilitation, all mitigation must be completed before Final Endorsement. Section 223(f) project repairs must be mitigated as soon as possible within a year of Initial Endorsement. The Radon Report must include a certificate of completion, included as an appendix, that radon testing and mitigation were completed. A cost estimate created from the property’s detailed plans and specifications is required per MAP Guide, Section 5.5. Estimates must match the average level of construction costs in the area where the construction occurs, and costs must go out to the estimated start of construction.
For refinancing projects within Radon Zone 1 and Radon Zone 2 (high and medium risk respectively), radon testing cannot be performed more than one year before the application is submitted, unless the applicant decides not to test and immediately initiates mitigation measures. Mitigation must comply with ASTM E 2121-11 or the most recent version. If the estimated costs are more than the cost allowed by Section 223(f) then the application cannot be approved as a Section 223(f) refinancing program but could be approved as a substantial rehabilitation program.
For Substantial Rehabilitation and Conversion projects in all Radon Zones, early testing may not be feasible or possible. If early testing is feasible, it must be performed no earlier than a year before the application is submitted. If early test results are below the accepted threshold, mitigation is not required, but if the results are 4 pCi/L or higher, the project design must include mitigation measures that comply with ASTM E 2121-11. If the project design does not include mitigation, radon testing must be completed after construction is finished but before the Final Endorsement. If the test results are 4 or more pCi/L, retrofit mandated by ASTM E 2121-11 is required.
New Construction projects must follow radon resistant construction regardless of Zone. For Radon Zone 1, all new construction projects must comply with all ASTM E 1465-08a requirements for passive system installation. Testing must be completed post-construction and before Final Endorsement, and if the results are 4 or more pCi/L then the passive system must be converted to a fan-powered system. For Radon Zones 2 and 3, there must be ASTM E 1465-08a compliant gas permeable layer, ground cover, and foundation walls to prevent radon from entering the residence. Radon testing must be completed after construction is finished but before the Final Endorsement. If the test results are 4 or more pCi/L, retrofit mandated by ASTM E 2121-11 is required as is installing a passive system. If the passive system does not lower the results, a fan-powered system must be installed.