1. Can Multifamily Buildings Have Radon?
Absolutely. Radon enters buildings through the foundation, and multifamily buildings have foundations just like single-family homes. Any building that is in contact with the ground can have radon, regardless of its size, age, or construction type.
The misconception that apartments and condos are safe from radon likely comes from the association between radon and basements. Since many multifamily buildings do not have traditional basements, people assume radon is not an issue. But radon enters through any contact point between the building foundation and the soil: slab-on-grade foundations, below-grade parking garages, utility penetrations, and elevator pits.
The EPA has consistently stated that multifamily buildings can have elevated radon and recommends testing, particularly for ground-floor and lower-level units. In Georgia, where several counties have high radon potential, multifamily buildings are subject to the same geological risk factors as single-family homes.
2. Which Units Are Most at Risk?
Radon risk in multifamily buildings follows a general pattern: the closer to the ground, the higher the potential radon level. However, the specifics depend on the building's design and construction.
Highest Risk: Ground-Floor Units
Units directly above the slab or foundation have the most direct contact with the soil gas source. These units should be tested as a priority in any multifamily radon assessment.
Moderate Risk: Second-Floor Units
Radon can migrate to second-floor units through stairwells, elevator shafts, utility chases, and gaps in the floor structure. The EPA recommends including second-floor units in testing protocols.
Lower Risk: Upper-Floor Units
Units on the third floor and above are generally at lower risk, but not zero risk. Building-specific factors like HVAC design, pressurization, and shaft connections can allow radon to reach upper floors in some buildings.
Below-Grade Areas
If your building has below-grade parking, storage, or common areas, these spaces can have significantly elevated radon levels. While people typically do not spend extended time in parking garages, maintenance workers, security staff, and residents who use below-grade storage areas may have meaningful exposure if levels are high.
3. Testing in Multifamily Buildings
The EPA provides specific guidance for radon testing in multifamily buildings. The recommended approach depends on the building's size and design, but the general protocol involves testing a representative sample of ground-floor and second-floor units, plus any common areas that are occupied for extended periods.
For smaller buildings (such as duplexes, triplexes, and small apartment buildings), every ground-floor unit should be tested. For larger buildings, a sampling approach may be used, with a minimum of 25% of ground-floor units tested. If any of the sampled units show elevated radon, additional testing of all ground-floor units is recommended.
Individual unit testing uses the same equipment and methods as single-family home testing: a professional continuous radon monitor is placed in the lowest livable area of the unit for 48 hours. Results are specific to that unit, since radon levels can vary significantly between adjacent units depending on foundation conditions, unit layout, and ventilation.
4. Who Is Responsible?
Responsibility for radon testing and mitigation in multifamily buildings varies depending on ownership structure and tenancy type.
Rental Apartments
The property owner or management company is generally responsible for maintaining a safe living environment. While Georgia does not specifically require landlords to test for radon, the EPA recommends it. Tenants can request testing or conduct their own with a DIY kit. If levels are elevated, the tenant should notify the landlord in writing.
Condominiums
In condos, the responsibility may be split between the unit owner and the HOA/condo association. Foundation and common area issues are typically the association's responsibility, while individual unit conditions may fall to the owner. Check your condo documents for specifics about environmental hazard responsibility.
Regardless of who is technically responsible, if you live in a multifamily building and are concerned about radon, you can always test your own unit. A DIY test kit costs $15 to $30, or a professional test costs $125 to $250. Having data is better than waiting for someone else to act. Review our guide to radon fan systems and contact our radon solutions for homeowners team for professional guidance on multifamily situations.
5. Mitigation Options for Multifamily
Radon mitigation in multifamily buildings uses the same fundamental principles as in single-family homes, but the scale and approach may differ. Understanding how radon enters buildings helps explain why certain units are affected more than others.
Sub-slab depressurization (SSD) is the most common approach for slab-on-grade multifamily buildings. One or more suction points are installed through the slab, connected to fans that create negative pressure beneath the foundation. A single well-designed system can often serve multiple units, depending on the sub-slab material and building layout.
For larger buildings, the system may require larger commercial-grade fans and multiple suction points. The pipe routing may need to accommodate the building's structure and aesthetics. An experienced commercial radon mitigator can design a system that is effective while minimizing visual and noise impact.
The cost of multifamily mitigation varies widely depending on building size and complexity. A small duplex might cost similar to a single-family home ($1,200 to $2,500). A large apartment building could cost several thousand dollars for a comprehensive system. However, the cost per unit is often lower than individual single-family mitigation because one system can serve multiple units.
6. Special Considerations for Condos
Condo owners face some unique challenges with radon. Because the building structure is shared, individual unit owners cannot typically install building-wide mitigation systems on their own. Getting the condo association involved is usually necessary for effective mitigation.
If you are buying a condo in Georgia, consider including radon testing in your inspection period, especially for ground-floor or second-floor units. If elevated levels are found, investigate whether the building has an existing mitigation system or whether the condo association has addressed radon in the past.
Some condo associations in Georgia have proactively tested and mitigated their buildings, particularly newer developments in north Georgia counties. Ask the association whether radon has been tested and what the results were. If they have not tested, consider proposing a building-wide assessment.
For Condo Buyers
If you are purchasing a ground-floor or second-floor condo, test for radon during your inspection period. If levels are elevated, you can negotiate with the seller and bring the issue to the condo association's attention. A building-wide mitigation system may be more cost-effective than individual unit solutions and benefits all residents.
