Can a condo on the 3rd floor have radon?

It is unlikely but not impossible. Radon concentrations decrease significantly above the ground floor because the gas dilutes as it moves away from the soil source. Third-floor and higher units rarely have radon above the EPA action level of 4 pCi/L. However, if building HVAC systems pull air from ground-level or basement areas, upper floors can occasionally show elevated levels. Testing is the only way to be certain.

Is the HOA responsible for radon testing in condos?

It depends on your HOA documents and local regulations. In Georgia, there is no law requiring HOAs to test for radon. Some HOA governing documents address environmental hazards, but most do not mention radon specifically. In practice, individual unit owners typically bear responsibility for testing their own units. Mitigation that involves shared building components (like drilling through common slabs or installing pipes on exterior walls) may require HOA approval and shared costs.

Do townhomes get radon?

Yes. Townhomes sit directly on the ground and have the same radon risk as detached single-family homes. Each townhome unit has its own foundation footprint in contact with soil, providing a direct pathway for radon entry. In fact, some townhome designs with shared walls and limited ventilation can concentrate radon more effectively than detached homes. Every townhome should be tested.

Can one unit in a townhome building have high radon while neighbors do not?

Absolutely. Radon levels can vary dramatically between adjacent units in the same building. Differences in foundation construction, soil composition under each unit, ventilation patterns, and even minor cracks can cause one unit to test at 8 pCi/L while the unit next door tests at 2 pCi/L. Each unit needs its own test.

Radon in Condos and Townhomes: Do You Need to Worry?

1. The Misconception About Multi-Unit Homes

There is a widespread belief that radon is only a problem for detached single-family homes with basements. This leads condo and townhome owners to skip testing entirely. The thinking goes: "I share walls with neighbors, I am not on the ground, radon does not apply to me."

The reality is more nuanced. Radon enters buildings from the soil through the foundation. Any living space that sits directly on or near the ground-level foundation has radon potential. That includes:

All townhomes (they sit directly on the ground)

Ground-floor condo units

Basement-level condo units (garden-level apartments)

Second-floor units directly above parking garages or crawl spaces

Check your area's risk level with our radon risk lookup tool to understand whether your zip code falls in a moderate or high-risk zone.

2. Which Units Are at Risk

Not every unit in a multi-unit building faces the same radon risk. The primary factor is proximity to the soil:

Unit Location	Risk Level	Testing Recommended
Basement / garden level	High	Yes, always
Ground floor (1st floor)	Moderate to High	Yes, always
2nd floor	Low to Moderate	Recommended if over garage/crawl
3rd floor and above	Low	Optional (low probability)

The HVAC Exception

If your building's HVAC system draws air from a basement or ground-level mechanical room, radon can be distributed to upper floors through the ductwork. This is uncommon in residential condos but does happen in some older buildings with centralized air handling. If your building has a shared HVAC system that pulls from below grade, upper-floor units should also consider testing.

3. Townhomes: A Special Case

Townhomes deserve special attention because they are often overlooked for radon testing, yet they face the same risk as detached homes. Each townhome unit sits on its own foundation footprint with direct soil contact. The shared walls between units do not change this fundamental fact.

Why Townhomes Can Actually Be Higher Risk

Tighter construction. Modern townhomes are built to be energy-efficient with tight building envelopes. Less natural air exchange means radon that enters the home is diluted less.

Smaller footprint, same soil. A townhome with a 1,000 sq ft foundation is sitting on the same geology as the 3,000 sq ft detached home next door. The radon production per square foot of soil is identical.

Basement-level living. Many Georgia townhomes have finished basement levels used as living space. These below-grade areas are in direct contact with more soil surface area and are the most common location for elevated radon readings.

One important point: your neighbor's radon result does not predict yours. Two adjacent townhome units can have very different radon levels based on subtle differences in soil, foundation cracks, and air pressure dynamics. Each unit needs its own test.

4. Condos: Floor-by-Floor Risk

Condo buildings range from two-story walk-ups to high-rise towers, and radon risk varies accordingly.

Garden-Level and Ground-Floor Units

These units have the same radon risk as a single-family home on a slab. The concrete slab floor is in direct contact with soil, and radon enters through the same pathways: cracks in the slab, gaps around utility penetrations, and construction joints. If you live in a ground-floor or garden-level condo in Metro Atlanta, testing is strongly recommended.

Second-Floor Units

Second-floor units generally have lower risk, but the construction matters. If the first floor is an open parking garage, radon can accumulate in the garage space and migrate upward. If the first floor is a sealed commercial space, less radon reaches the second floor. Second-floor units above slab-on-grade construction should consider testing, especially in high-risk zip codes.

Third Floor and Above

By the third floor, radon risk drops significantly. The gas has diluted through multiple floor levels and any air exchange. In most cases, third-floor and higher condo units do not need radon testing unless there is reason to believe the building's air handling system distributes ground-level air upward.

5. Who Is Responsible for Testing

This is where multi-unit living gets complicated. Responsibility for radon testing and mitigation depends on your ownership structure and governing documents.

Townhomes

In most townhome communities, each owner is responsible for the interior of their unit, including environmental concerns like radon. The HOA typically manages exterior common areas and shared structures, but radon inside your unit is your responsibility. Testing is straightforward because each unit is self-contained with its own foundation.

Condos

Condos are trickier. The slab beneath your unit is often a common element owned by the association, not by you individually. This means:

Testing your unit: You can and should test without HOA approval. Place the test in your living space.

Mitigation: If mitigation requires drilling through the shared slab or installing equipment on the building exterior, you will likely need HOA approval and possibly shared cost arrangements.

Building-wide testing: Some progressive HOAs conduct building-wide radon assessments, especially in areas with known radon risk. This is rare but becoming more common.

6. Mitigation in Shared Buildings

Mitigating radon in a multi-unit building requires some creative problem-solving, but it is absolutely doable.

Townhome Mitigation

Townhome mitigation is essentially the same as single-family home mitigation. A sub-slab depressurization system is installed with a suction point through the unit's slab, a PVC pipe run, and a fan venting above the roofline. The only complication is pipe routing on the exterior, which may require HOA architectural approval. Costs are typically the same as single-family mitigation: $1,200-$2,500 for slab foundations.

Condo Mitigation

Condo mitigation options depend on the building type:

Single-unit system: A suction point can be installed through your unit's slab with the pipe routed to an exterior wall. This works well for ground-floor units with exterior wall access.

Building-wide system: For buildings with multiple affected units, a single larger system with multiple suction points and a shared vent pipe is more cost-effective. The cost is shared among benefiting units.

Sealing and ventilation: In some cases, sealing radon entry points combined with improved ventilation can reduce levels without a full depressurization system. This is less reliable but can work for borderline situations.

Use our cost estimator to get a ballpark figure for your specific situation.

7. Buying or Selling a Condo with Radon

Radon testing during condo and townhome sales follows the same principles as single-family transactions, with a few additional considerations.

For Buyers

Always test ground-floor and garden-level condos during inspection

Always test townhomes regardless of floor level

Ask whether the HOA has conducted any building-wide radon testing

Review HOA documents for any policies on environmental hazard remediation

For Sellers

Consider pre-listing testing, especially for ground-floor units

If you have a mitigation system, include documentation with the sale

Disclose any known radon test results to avoid potential liability

Radon in Condos and Townhomes: Do You Need to Worry?

1. The Misconception About Multi-Unit Homes