What are average radon levels in Roswell, Georgia?

Average radon levels in Roswell range from 3.5 to 5.0 pCi/L, which is higher than the Fulton County average overall. Roswell sits on granite bedrock in North Fulton that produces more radon than areas further south. Roughly 25-35% of Roswell homes tested exceed the EPA action level of 4 pCi/L.

Why does Roswell have higher radon than other parts of Atlanta?

Roswell sits on the Piedmont granite belt where uranium-bearing bedrock is closer to the surface than in central or south Atlanta. The granite produces more radon gas, and the shorter distance to home foundations means less dilution before the gas enters living spaces. The prevalence of homes with basements in Roswell also contributes to higher indoor readings.

How much does radon mitigation cost in Roswell?

Radon mitigation in Roswell typically costs $1,200 to $2,500 for homes with slab or basement foundations using sub-slab depressurization. Crawl space homes may cost $2,500 to $5,000 due to the additional work of installing and sealing a vapor barrier. Most systems are installed in a single day.

Should I test for radon when buying a home in Roswell?

Yes. With 25-35% of Roswell homes testing above the EPA action level, radon testing during the inspection period is highly recommended. Professional CRM testing costs $125-250 and provides leverage to negotiate mitigation if elevated levels are found. Georgia does not require radon testing for real estate, so it is up to the buyer to request it.

Radon in Roswell, Georgia: What Homeowners Need to Know

1. Why Roswell Has Elevated Radon Risk

Roswell is located in North Fulton County on the Piedmont geological province, a region defined by ancient metamorphic and igneous rock. The granite bedrock beneath Roswell contains trace amounts of uranium that decay into radium and then into radon gas. This gas migrates upward through soil and enters homes through foundation cracks, pipe gaps, and other openings.

What makes Roswell notable among Metro Atlanta cities is the depth of its bedrock. In many parts of Roswell, granite sits relatively close to the surface, which means radon gas has a shorter path to travel before reaching home foundations. This contributes to Roswell's above-average radon readings compared to other parts of Fulton County.

The city's housing stock ranges from historic homes along the Chattahoochee River to modern subdivisions in the eastern and southern parts of the city. With over 95,000 residents across a variety of foundation types, radon is a widespread concern. The only way to know your home's level is to test for it.

2. Neighborhood Radon Risk Areas

Radon levels vary across Roswell based on geology, soil depth, and home construction. While every home needs individual testing, these areas show patterns worth noting:

Historic Roswell. The historic district along the Chattahoochee features many older homes with basements and crawl spaces. These homes were built before radon awareness and often have more foundation openings. Many homes in this area test above 4 pCi/L due to the combination of older construction and shallow granite.

Riverside. This area along the river corridor tends to have homes with walk-out basements built into the hillside. The below-grade portions of these homes have significant soil contact, making them particularly vulnerable to radon entry. Testing data from Riverside consistently shows elevated readings.

Mountain Park. Located on higher terrain with granite close to the surface. The geology here is among the most radon-productive in the Roswell area. Homes with basements in Mountain Park frequently test in the 4-8 pCi/L range.

Crabapple. This growing area in northern Roswell has a mix of older properties and new developments. New construction is not immune to radon. The underlying geology still produces radon gas regardless of when the home was built.

Use our radon risk lookup tool to check the risk level for your specific Roswell zip code.

3. Foundation Types and Radon Entry

Roswell has a diverse mix of foundation types, and each one creates different radon entry conditions:

Full and walk-out basements. Very common in Roswell due to the hilly terrain. Basements have the most soil contact and the highest radon accumulation potential. Walk-out basements along hillsides can have three walls in contact with soil. Radon enters through floor cracks, wall-floor joints, and utility penetrations.

Crawl spaces. Found in many older Roswell homes, especially in the historic district. Open or poorly sealed crawl spaces allow radon to accumulate beneath the home and migrate into living areas through floor gaps and HVAC ductwork.

Slab-on-grade. Found in newer ranch-style homes and townhome communities. While slabs have less soil contact than basements, radon enters through the natural cracks that form in concrete, plus plumbing penetrations and expansion joints.

Roswell's Granite Geology Affects All Foundation Types

The shallow granite bedrock beneath Roswell produces radon that can affect any home regardless of foundation type. Basements tend to accumulate the most radon, but slab and crawl space homes in Roswell regularly test above the EPA action level too. Testing is the only way to know.

4. Testing Your Roswell Home

Testing is straightforward and affordable. Here is the recommended approach for Roswell homeowners:

Choose Your Test Type

A short-term test (48 hours minimum) works well for screening. For real estate transactions, professional CRM testing is the standard. DIY kits cost $15-40 plus lab fees for general use.

Place the Test Correctly

Test in the lowest livable area. For homes with basements, that means the basement. For slab-on-grade homes, test on the main floor. Keep the device away from windows, drafts, and exterior walls. Maintain closed-house conditions during testing.

Interpret Your Results

Below 2 pCi/L: Low risk, retest every 2 years. Between 2-4 pCi/L: Consider a long-term follow-up test. Above 4 pCi/L: The EPA recommends mitigation. Above 8 pCi/L: Prioritize mitigation promptly.

Keep in mind that radon levels fluctuate seasonally. Homes tested in winter typically show levels 40-60% higher than summer. A borderline summer result warrants retesting in colder months. Read our home inspection radon guide if you are buying a home in Roswell.

5. Radon Mitigation Options

If your Roswell home tests above 4 pCi/L, mitigation is effective and typically completed in one day. The approach depends on your foundation type:

Slab or Basement

$1,200-$2,500

Sub-slab depressurization: a suction point drilled through the slab, connected to PVC pipe and a fan that vents radon above the roofline.

Crawl Space

$2,500-$5,000

Sub-membrane depressurization: a sealed vapor barrier covers the soil with active suction pulling radon from beneath the membrane.

Both systems achieve 90-99% radon reduction. Use our mitigation cost estimator for a more specific estimate based on your Roswell home.

Roswell Homeowners

Roswell has some of the highest radon potential in Fulton County. With 25-35% of homes testing above the action level, testing is not optional. A 48-hour test gives you a definitive answer, and if mitigation is needed, it is a one-day installation that solves the problem permanently.

Radon in Roswell, Georgia: What Homeowners Need to Know

1. Why Roswell Has Elevated Radon Risk

2. Neighborhood Radon Risk Areas

3. Foundation Types and Radon Entry

Roswell's Granite Geology Affects All Foundation Types