Factors Impacting Radon Levels in Georgia Homes

For homes in Georgia, and essentially everywhere, one of the main contributors to poor Indoor Air Quality (IAQ) is elevated levels of radon within the home. Where does radon come from? Radon is a radioactive gas from the decay of uranium found in Earth’s soils. As uranium decays, it turns into radium, which further decays into radon gas. From home to home, radon levels will be completely different due to a variety of factors working both independently and simultaneously. We’re going to take a building science approach to look at some of the factors impacting radon levels in Georgia homes.

Radon in Georgia

Georgia Soil

Georgia is well known for its hard and dense red clay soil. Clay soils are generally less permeable than other types of soils, which means they are slower to allow water and gas to move through them. Despite our tough Georgia red clay soil, radon is still able to move through, albeit at a slower rate.

Radon and Stone Mountain

Stone Mountain Park is the home of one of Georgia’s most beloved tourist attractions. Sitting on the East Side of metro Atlanta in Dekalb County, Stone Mountain is the largest piece of exposed granite in the world. When magma or lava cools, it crystalizes and becomes solid forming igneous rock. This type of rock is very commonly found in mountainous areas. Granite, a type of igneous rock, forms the large dome of Stone Mountain. More information on this and other characteristics of Stone Mountain can be found here: A Geologist’s Dream: The Rock Behind Stone Mountain Park.

Radon comes from the decay of Uranium. While granite is a rock known to contain uranium deposits, the uranium content in granite is typically very minimal. Obviously, this will contribute to elevated levels of radon in homes near Stone Mountain, but the issue still stems much more from the underlying bedrock rather than the granite itself. So whether a home is near Stone Mountain or not, there is still substantial risk for elevated levels of radon.

Radon Testing and Radon Mitigation for Homeowners near Stone Mountain Georgia.

Factors Impacting Radon Levels

Soil Permeability

Moving closer towards the surface of the Earth, soil typically becomes more permeable. Radon travels up from beneath the soil through the path of least resistance. The more permeable the soil is under a home's foundation, the more potential there is for elevated levels of radon in the home.

Soils with higher permeability allow radon to move more easily through them.
Soils with higher permeability allow radon to move more easily through them.

Building Envelope

Radon has the potential to become concentrated in homes with tighter building envelopes. Enhancing building envelope integrity is a key strategy for builders when optimizing new constructions for energy efficiency. However, builders also need to account for Indoor Air Quality issues as a result, particularly with radon. With proper ventilation measures in place, a tight building envelope will be a major positive for energy efficiency and even home health.

Home foundation Type (Basement, Crawlspace, Slab)

Homes built on crawl spaces and basements can potentially have higher levels of Radon over slab homes. Basement and crawl space homes are exposed to more soil at the foundation. Nevertheless, slab homes are still susceptible to elevated levels of radon as well. As a porous material, radon atoms have no problems traveling directly up through a concrete slab. Radon also likes to travel in through cracks in the foundation. Cold joints are a very common path of entry for radon to accumulate within the home. 

Temperature Differentials

Temperature differentials between the inside and outside will have an impact on the stack effect (natural flow of air) in a building structure. Temperature changes create positive and negative pressure differentials within buildings and thus impacting the stack effect. These building dynamics can contribute to more draw of Earth gases up and into the home from beneath.

As warm air rises and leaves the home, cold are is ingested from below. Along with the makeup air coming in, radon from the soil is ingested into the home.

Activity of Home Occupants

The presence and activity of occupants in the home can have an impact on building dynamics. When occupants open doors and windows frequently, this can help dissipate concentrated radon in the home. Likewise, ventilation from running the HVAC system can have a positive effect towards reducing radon levels. On the contrary, running appliances like bathroom fans, the dryer, or a range hood creates a negative pressure in the home. Once the home begins to depressurize, radon gasses can be drawn from the soil below via the stack effect.

Climate and Weather conditions

Radon levels can be higher in homes during certain times of the year. During the winter season, homes are being heated, pushing hot air upwards. This creates a negative pressure below causing more Earth gasses to be drawn in from the soil by the stack effect. Rainfall creates conditions that affect radon levels in the home temporarily. Rainfall brings changes in barometric pressure which ultimately impacts pressure on the home. Rainfall can also temporarily change the path of least resistance for radon due to how it creates a capping effect on the soil (Why Rainfall Elevates Radon Levels in Your Home).

The Solution is Radon Mitigation

First off, in order to identify if there is a radon problem in any home, the only way to know is to perform testing. As a colorless, odorless, and tasteless gas, Radon is undetectable to the human senses. Reliable testing can be performed by using a Radon Test kit or by calling a certified professional Radon tester.

EPA Recommendations

  • Every single home should be tested
  • Testing should be performed every 2 years, even after a mitigation system has been installed

Radon Mitigation is not prevention, but rather risk management. Even outdoors, Radon is all around us. The primary concern with radon is its ability to accumulate within homes, leading to prolonged exposure to high concentrations of the gas. 

Radon Mitigation Systems

When elevated levels of Radon are discovered, pre-existing homes can be retrofitted with a Radon Mitigation System. These systems are designed to draw up radon gas from beneath the home and provide a vent path for escape before radon can accumulate indoors. These systems operate with a fan actively drawing up radon gas at all times. Studies show, radon mitigation systems have the potential to reduce radon levels by up to 99%. 

  • Sub-Slab Depressurization System (Slab and Basement homes)
  • Sub-Membrane Depressurization System (Crawl Space Homes)

Basement Home Radon Mitigation System
Sub-Slab Depressurization System

Radon Resistant New Construction

Radon Resistant New Construction (RRNC) is a critical component in building healthier and more energy efficient homes. Builders can install a passive radon vent system into the foundation of the home and direct it up and out of the home through the roof. The advantage of building this system into the home is that it utilizes the natural stack effect to collect Earth gasses from beneath  and vent them up and out through the roof. The Studies show a passive Radon vent system can reduce radon levels by up to 50%. If necessary, the system can be easily made active by adding a fan for even more effectiveness. If you are interested in more information about this, read our post on 5 Advantages of Installing a Radon System During New Construction



Homeowners, test your home for radon regularly. Even if your home has a radon mitigation system installed, it is still necessary to perform regular testing as a way to monitor the effectiveness of the system over time. Affordable devices can be purchased to monitor radon levels within your home. Although, the most accurate and reliable method is to have your home tested by a home inspector or indoor environmentalist.

Real Estate Agents

For real estate transactions, it is recommended to always have a certified radon professional perform testing and correct any issues with radon in the home.


As a custom home builder, Ensign prioritize radon education for our clients, emphasizing the merits of proactive measures that lower risk by reducing exposure levels. Our hope is that all home builders will take the initiative to build healthier homes responsibly. Ensign is well equipped and ready to help home builders across Georgia to Build Radon Out.

Suggested Top Rated Products
No items found.
Read More
Call Us

Call to Schedule an assessment with one of our certified experts.


- Or -
Leave A Note

Fill out our contact form and we will reply back within 24 hours.

Leave a detailed message on our contact form.