VERTEX has Experts that Talk the Talk and Walk the Walk.

Unlike others, VERTEX provides forensic consulting alongside traditional AEC services which allows for a 360 degree view of your project.

VERTEX Services


Need an expert for your case?

Our forensics experts work alongside AEC specialists which enhances our skills and bolsters the credibility of our expert consultants.

Find an Expert


VERTEX delivers innovative solutions on complex projects globally.

Since 1995, VERTEX has completed over 90,000 projects.

View Portfolio


VERTEX believes in a Lifetime of Learning philosophy.

Stay current with our industry experts as they share their insights and knowledge on the built environment.

View Insights

Grow Your Career

Join Our Team

VERTEX is looking for talented individuals to join a highly technical team of forensic consultants, design engineers, construction managers, and environmental scientists.

Learn More

Contact Us

Have a question or want to speak with a technical professional?

VERTEX is a multi-discipline firm with global coverage. Our international network of resources enables us to provide multi-national clients with the most qualified local professionals who understand the culture, language, and regulatory framework.

Call Us: 888.298.5162

Call Us

Call us at 888.298.5162.

Radon multifamily policy

New Fannie Mae and Freddie Mac policy increases radon testing requirements for multifamily buildings

March 31, 2000

Earlier this year Fannie Mae and Freddie Mac updated their policy on the collection or radon samples from multifamily buildings. A multifamily building is generally considered a building with more than 5 units. The policy change will go into effect on June 20, 2023. The increased requirements will be included in Phase I Environmental Site Assessments typically prepared during the refinance or sale of a property. Below is a list of the major changes that are going to go into effect:

  • (2) Changing the minimum sample rate from 10% of the lowest floor to 25% of the lowest floor
  • (3) Requiring an Environmental Professional to manage radon testing
  • (4) Requiring that tenants are notified for radon testing with specific language in the notification indicating the conditions required to maintain a valid test
  • (5) Requiring conformance with State and Local Radon Regulations
  • (1) Establishing when re-testing or when radon mitigation is required

Changing the minimum sample rate from 10% of the lowest floor to 25% of the lowest floor.

The change is an increase in the total number of tests required at a property. At least one sample must be collected from every building even if that increases the sample frequency to more than 25%. This is more in line with the current U.S. Department of Housing and Urban Development (HUD) sampling frequency but below the American Association of Radon Scientists and Technologists (AARST) sampling frequency required in some states and municipalities.

Sampling will not be required if there are no ground contact units, new construction has been completed following the radon resistant new construction (RRNC) requirements, properties that are being refinanced and are compliant with the 25% sampling frequency, or if the environmental professional documents that sampling is not required.

Requiring an environmental professional to manage radon testing.

An environmental professional is defined in 40 CFR 3.12.10 and is generally considered a person who possesses sufficient specific education, training, and experience necessary to exercise professional judgment to develop opinions and conclusions regarding conditions indicative of releases or threatened releases on, at, in, or to a property, sufficient to meet the objectives and performance factors of § 312.20(e) and (f). This includes the following:

  • Hold a current Professional Engineer’s or Professional Geologist’s license and have the equivalent of three (3) years of full-time relevant experience; or
  • Be licensed or certified by the federal government, a state, tribe, or U.S. to perform environmental inquiries as defined in § 312.21 and have the equivalent of three (3) years of full-time relevant experience; or
  • Have a Baccalaureate or higher degree from an accredited institution of higher education in a discipline of engineering or science and the equivalent of five (5) years of full-time relevant experience; or
  • Have the equivalent of ten (10) years of full-time relevant experience.
  • The environmental professional must also meet state and local requirements for services provided.

Requiring that tenants are notified for radon testing or mitigation with specific language in the notification

Tenant notification requirements will be upgraded to more closely align with the AARST National Radon Proficiency Policy (NRPP) ANSI Standards Protocol for Conducting Measurements of Radon and Radon Decay Products in Multifamily Buildings (2017 updated 2020) (AARST-ANSI Standard) and must include, at a minimum:

  • Dates and times for canister deployment and retrieval;
  • Instructions on how tenants can maintain proper testing environments
  • Information on how to obtain federal or state radon health guidance
  • Local contact information for inquiries

Requiring Conformance with State and Local Radon Regulations

Several states and local municipalities have more robust sampling requirements or require compliance with the AARST ANSI Standard. Key AARST ANSI Standard requirements include the following:

  • Sampling 100% of lowest level units (in some cases with 100% duplicates)
  • Sampling 10% of upper-level units by floor
  • Tenant certification of closed house conditions
  • Pre-mitigation diagnostic testing
  • Hiring of a person certified by the NRPP or National Radon Safety Board (NRSB) and/or licensed in the state in which the samples are being collected

Establishing when re-testing or when radon mitigation is required.

Retesting is required when more than 15% of the initial test kits are lost or rendered invalid., Retesting may also be required when concentrations of radon are measured above the USEPA Action Level of 4 pCi/L in a single test. Tests following an exceedance of the USPEA Action level may be short or long-term tests and may require testing of additional units.

The updated guidelines requires a qualified radon mitigation firm to assess whether what type of radon mitigation system is required. An Operation, Maintenance and Monitoring Plan (OMM Plan) which includes periodic inspections of the radon mitigation system must be provided and adhered to following mitigation.

The Vertex Radon Measurement and Mitigation Team

The VERTEX team consults with the nation’s leading multifamily residential owners, developers, and managers. Our team offers comprehensive services to ensure compliance with new policies regarding radon testing in multifamily residential properties. With a team of certified professionals and experience in environmental due diligence, VERTEX is well-equipped to provide thorough radon testing, management, and mitigation services. Our commitment to client satisfaction and quality results makes our team reliable partners for any property owner or manager seeking to ensure the safety and well-being of their tenants.

VERTEX personnel have the following certifications:

  • Residential Radon Measurement
  • Multi-Family Radon Measurement
  • Residential Mitigation
  • Multi-Family Mitigation
  • Radon Resistant New Construction

If you have any questions or additional information, please reach out to Jesse Freeman at or by phone at (617)-275-5407.

Jesse Freeman, P.E., LSP

  • Residential Radon Measurement #108637-RMP
  • Multi-Family Measurement Certificate (MFM)
  • Residential Radon Mitigation #108891-RMS
  • Multi-Family Mitigation Certificate (MFMT)
  • Radon Resistant New Construction Certificate (RRNC)
Back to Insights