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How Radon Enters Your Home

Radon gas enters the home through the slab, basement, or crawl space. Pressure differences within the home (from warm air rising and other natural effects) pull radon into living spaces from the soil. Furnace & air conditioning systems can distribute the air throughout the entire house.

Radon House Graphic

How Radon Enters Your Home

1 - Soil


Uranium deposits int the soil and rock are the main cause of elevated radon levels in your homes. The pressure difference between the inside and outside of your home, your home creates a vacuum that pulls radon through foundation cracks and other openings.

2 - Cracks


All exposed cracks and other openings in the floor of the lowest level of the home can allow Radon to enter your home. Because radon is a radioactive gas, it can enter the home without cracks or openings. While sealing cracks can be beneficial to the radon systems performance, sealing is not recommended as a stand alone solution. 

3 - Drainage


An open drain tile system (a gap between the concrete floor and wall) will allow radon to enter in the home at a faster rate and increase the levels of radon. A sump can also be another area where Radon can enter your home. Radon levels should be checked if either of these improvements have been made to your home since your last radon test.

4 - Water


Radon entering the home through water is a small risk compared with radon entering your home from the soil. Well water can can bring Radon into the home through the shower or other water sources.

While sealing may be a necessary part of the radon mitigation process, the EPA does not recommend the use of sealing alone to reduce radon because by itself, sealing has not been shown to lower radon levels significantly or consistently.

Any home may have a radon problem, new or old with or without a basement, sealed basement or not.

Radon from soil gas is the main cause of radon problems. Other less common sources include well water and building materials. Measuring radon concentration in the air is recommended for initial testing.



The first step to help ensure the safety of you and your family’s health and safety is to have your home tested for radon. At St. Louis Radon, our professional testers deploy the latest in computerized electronic real-time radon monitoring technology to provide you with a comprehensive report, including a complete visual graph of radon level data points as recorded over a 48-hour sampling period.

Learn More About Testing


If testing indicates levels of radon that require action, our team of engineers and technicians will design and install a custom radon mitigation system to safely and effectively redirect radon and other soil gasses out of your home. We also take additional measures to seal and close other possible breaches in the foundation that could let soil gasses into the through cracks or drain tiles systems.

Learn More About Mitigation

New Construction

With new home construction projects, it is crucial to determine the level of radon that may be present in the soil before the home is built. It’s also critical to have the new home retested for potential radon concentrations immediately following occupancy. We also highly recommend installing an Active Dampness Control System (ADC) with every new build.

Learn More About New Construction