Yes — radon testing is required by law in Montgomery County, and it matters more here than almost anywhere else in the country. Since October 2016, Montgomery County has required a radon test on every single-family home and townhome sale, performed sometime between one year before settlement and no later than the settlement date itself. That’s not a typical disclosure form or a suggestion — it’s a legal requirement, and Montgomery County is the only county in the entire United States that mandates it. Whether you’re buying, selling, or just living in the home you already own, radon isn’t a topic you can afford to skip. Here’s what it actually is, why our area gets hit harder than most, and what to do about it.
What Is Radon and Why Should You Care?
Radon is a colorless, odorless, tasteless gas that forms naturally underground as uranium in the soil breaks down over time. You can’t see it, smell it, or taste it, which is exactly why it’s dangerous — there’s no warning sign without a test. Outdoors, radon disperses into the air and isn’t a real concern. The problem starts once it seeps into an enclosed space like your basement, where it has nowhere to go and can build up to levels that pose a genuine health risk. Long-term exposure to elevated radon levels has been linked to lung cancer, which is why health agencies treat it as a serious indoor air quality issue rather than a minor nuisance.
How Does Radon Get Into Your Home?
Radon enters through cracks and gaps in your foundation or slab, and the most common entry point I see is the sump pit. Because radon is produced in the soil beneath your house, it’s constantly pushing upward looking for a path of least resistance. Foundation cracks, gaps around pipes, and unsealed sump pits all give it an easy way in. Once it’s inside a basement or lower level, it gets trapped rather than diluted the way it would be outdoors, which is how levels can climb over time without anyone in the house noticing anything different.
Why Is Montgomery County Considered High Risk for Radon?
Montgomery County is classified as Zone 1 by the EPA, which is the highest-risk category for radon exposure in the country. The EPA, along with state and federal geologists, mapped radon potential across the country in zones — Zone 1 counties have the highest average indoor radon levels, and Zone 3 counties have the lowest. Montgomery County lands in Zone 1 because the average home here tests at or above the EPA’s action level, the threshold at which the agency recommends taking corrective steps. That’s not a scare tactic — it’s a reflection of what’s actually in the soil we’re built on, and it’s the reason our local law treats radon testing as mandatory rather than optional.
Can Radon Be Fixed, and What Does It Cost?
Yes, radon is very correctable, and the systems used to fix it are simpler than most people expect. A typical radon mitigation system uses PVC piping routed under the slab connected to a fan that continuously pulls radon out from beneath the home and vents it safely outside. It’s not exotic technology, and licensed contractors install these systems regularly. Cost-wise, I typically see mitigation systems run somewhere between $800 and $1,200, and that price usually includes a retest afterward to confirm the levels have dropped. Given the health stakes, that’s a relatively small investment for peace of mind.
Who Pays for the Radon Test When Selling in Montgomery County?
Who pays for the radon test is negotiable between the buyer and seller — it’s not fixed by law. The county requires the test itself, but it doesn’t dictate who foots the bill. In practice, I’ve seen sellers cover it, buyers cover it, and sometimes a third party handles it as part of negotiations. This is exactly the kind of detail that gets worked out in a strong offer or listing strategy, which is one more reason to have an experienced agent involved on either side of the transaction. If you’re preparing to sell, ourguide to selling a homewalks through what else you’ll want to line up before listing. If you’re on the buying side, check out ourguide to buying a homefor what to expect during inspections and negotiations.
Do You Need a Radon Test If You’re Not Selling?
Yes — radon testing is worth doing even if you have no plans to sell anytime soon. Radon exposure is a health issue first and a real estate compliance issue second. It’s essentially impossible to find a home with zero radon present, and the level in your home has nothing to do with how well it was built or how new it is. It comes down entirely to what your home is sitting on top of, meaning even a beautifully constructed, high-end home can test high for radon. If you live in Montgomery County and haven’t tested your own home recently, it’s worth doing regardless of your plans to move.
For more detail on radon risk levels, testing methods, and the EPA’s action guidelines, theEPA’s radon information pageis a solid resource, and Maryland homeowners can also check theMaryland Department of the Environment’s radon programfor state-specific guidance and licensed mitigation contractor requirements.
Frequently Asked Questions
Is radon testing legally required to sell a home in Montgomery County?
Yes. Since October 2016, Montgomery County law requires a radon test on every single-family home and townhome sale, completed no earlier than a year before settlement and no later than settlement itself.
Is Montgomery County really the only place with this requirement?
Yes. Montgomery County is currently the only county in the United States with a legal mandate for radon testing in home sales. Everywhere else, testing is discretionary and typically requested by the buyer.
How much does it cost to fix a high radon reading?
A typical mitigation system, including a PVC vent pipe and fan, generally runs between $800 and $1,200, and usually includes a retest to confirm the fix worked.
Does a high radon level mean the home was poorly built?
No. Radon levels are tied to the soil and geology under the home, not construction quality. Even well-built, newer homes can test high because of what’s underneath them.
Who pays for the radon test, the buyer or the seller?
It’s negotiable. Maryland law requires the test to happen, but who pays for it — buyer, seller, or a shared arrangement — gets worked out during the transaction.
Radon isn’t a topic anyone gets excited to talk about, but in Montgomery County it’s not optional — it’s the law, and more importantly, it’s your family’s health. Whether you’re getting ready to list your home, under contract to buy one, or just haven’t thought about it in years, get it tested. If you want to talk through what this means for your specific situation, or you’re weighing a move in or around Montgomery County,reach out anytimeor read more aboutwhy clients choose to work with me.
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