Buying a home anywhere in the Chicago area is one of the biggest financial decisions you will ever make, and radon is a factor that deserves serious attention. Whether you are eyeing a split-level in Wheaton, a bungalow in Oak Park, or a ranch home in Naperville, elevated radon levels can show up in any property. Here is what every local buyer and seller should understand about radon and radon mitigation before the deal closes.
What Is Radon and Why Is It Dangerous?
Radon is a colorless, odorless, radioactive gas that forms naturally from the breakdown of uranium in soil, rock, and groundwater. It rises from the ground and can accumulate to hazardous concentrations inside homes, particularly in lower areas like basements and crawl spaces where air exchange is limited.
What makes radon especially concerning is that there is no way to detect it without testing. You cannot see it, smell it, or feel it. According to the EPA, radon is the second leading cause of lung cancer in the United States, accounting for roughly 21,000 deaths each year.
In the Chicago metro area and throughout DuPage County communities, radon is a well-documented issue. Illinois is classified as a high-radon state, with many local neighborhoods falling in the EPA’s Zone 1 category. That designation means predicted average indoor radon levels exceed 4 picocuries per liter, which is the threshold at which radon mitigation is strongly recommended by health authorities.
No property is immune, regardless of age, construction style, or neighborhood.
How Does Radon Get Into a House?
Radon does not need a large opening to enter a home. It migrates through the smallest gaps and porous materials, often going entirely unnoticed until a test reveals elevated levels. In Chicago-area homes, where basements are common and older construction is widespread, there are several typical entry points to be aware of.
- Foundation cracks: Even hairline fractures in concrete slabs and basement walls allow radon gas to seep in from the surrounding soil, making them one of the most frequent entry routes in older Chicago-area homes.
- Construction joints: The seams where walls meet floors, or where different building materials connect, create natural pathways for radon gas to travel from the ground into the living space.
- Sump pump pits: Open or inadequately covered sump pits act as a direct channel, drawing soil gases, including radon, straight into the basement.
- Porous concrete blocks: Many older homes throughout DuPage County were built with hollow block foundation walls, which allow radon to pass through the material itself rather than through a visible gap.
- Gaps around utility penetrations: Wherever pipes, cables, or other utility lines enter the foundation, small unsealed gaps can serve as consistent entry points for radon infiltration.
Does the Seller Have to Disclose High Radon Levels?
In Illinois, sellers are required by law to disclose known radon conditions when selling a residential property. Under the Illinois Radon Awareness Act, sellers must provide buyers with relevant information, including any known test results or prior mitigation history.
That said, the disclosure requirement applies to what the seller already knows. If a home was never tested, the seller is generally not obligated to report a problem they had no knowledge of. This is why buyers throughout the Chicago area are strongly encouraged to include radon testing as a standard part of the home inspection process.
Radon disclosure is becoming an increasingly common element of real estate transactions in Wheaton, Naperville, Oak Park, and surrounding communities. Many experienced local real estate agents now routinely recommend it, particularly for homes with basements or below-grade living areas.
If a radon test comes back elevated, buyers often find themselves in a stronger negotiating position than they anticipated. Radon removal and mitigation is a fully established, proven process. The presence of elevated radon levels does not have to end a deal.
What Should You Do If the Radon Test Comes Back High?
Discovering elevated radon levels during a home purchase can feel alarming, but it does not have to derail the transaction. Many Chicago-area buyers successfully navigate this situation every year. The key is knowing your options and acting strategically from the start.
- Request a radon mitigation contingency: Make radon mitigation a formal condition of your purchase agreement. This means the sale cannot proceed until the radon issue is addressed to a mutually agreed-upon standard before closing.
- Negotiate who covers the cost: In many transactions, buyers can negotiate for the seller to cover the cost of a professional radon mitigation system installation prior to the closing date.
- Get a professional evaluation: Have a licensed, certified radon mitigation contractor evaluate the home to understand the full scope of work required and to receive an accurate cost estimate.
- Require post-mitigation verification: Any radon mitigation work should be followed by verification testing to confirm that levels have been reduced to an acceptable range, ideally below 2 pCi/L.
- Keep perspective on the process: Modern radon mitigation systems are highly effective and widely used throughout the Chicago area. Elevated radon is a solvable problem, not a reason to walk away from the right home.
How Effective Is Radon Mitigation?
Radon mitigation is one of the most reliable and well-proven approaches in the residential home improvement space. When installed by a certified contractor, a radon mitigation system can reduce indoor radon concentrations by up to 99 percent in most homes. For Chicago-area buyers weighing their options, that context matters significantly.
- Sub-slab depressurization is the gold standard: The most widely used radon mitigation method involves inserting a pipe through the foundation slab and using a fan to draw radon from beneath the slab before it can enter the home, redirecting it safely above the roofline.
- Results are fully measurable: Post-mitigation verification provides concrete confirmation that radon levels have dropped to within acceptable ranges, giving both buyers and sellers documented proof that the system is working as intended.
- Systems require minimal upkeep: Once installed, a radon mitigation system requires very little ongoing maintenance. A periodic check of the pressure gauge is typically all that is needed to confirm the system is functioning properly.
- Radon removal is a long-term solution: A properly designed and installed system can last for decades, providing continuous protection without requiring regular intervention or replacement.
- Custom configurations exist for complex homes: For properties with multiple foundation types, crawl spaces, or unconventional construction, experienced contractors can engineer systems that address each unique structural challenge.
Does the Buyer or Seller Pay for Radon Mitigation?
There is no universal rule governing who pays for radon mitigation in a real estate transaction. It is almost always a matter of negotiation between the buyer and seller, shaped by local market conditions, the terms of the purchase agreement, and how motivated each party is to close.
In a buyer’s market, sellers are generally more willing to absorb the cost of radon mitigation to keep the transaction on track. In a competitive seller’s market, as parts of the Chicago area have experienced in recent years, buyers may be asked to accept the home as-is or agree to handle mitigation costs after closing.
A common middle-ground approach is a seller credit. Rather than completing the work themselves before closing, the seller offers the buyer a financial credit at the closing table to cover the cost of radon mitigation after the sale is final.
Regardless of how the cost is divided, buyers should insist that any mitigation work be completed by a licensed, certified contractor. Proper installation and post-mitigation verification protect everyone involved and ensure the system meets Illinois regulatory standards.
Work With a Certified Radon Mitigation Expert in the Chicago Area
Elevated radon levels should not stop you from buying the right home. With a qualified mitigation contractor on your side, this issue is entirely manageable. DuPage Radon’s certified team brings over 30 years of expertise to every residential project across the Chicago area. If you are in the process of buying or selling a home and need professional radon mitigation, reach out to our team today to learn more about your options and get started.