A home can look well maintained, smell clean, and still have a radon problem. That is what makes this gas easy to miss. If you are wondering how to test for radon, the good news is that the process is straightforward when it is done correctly, and the results can give you clear direction before you buy, sell, or make improvements.
Radon is a naturally occurring radioactive gas that forms as uranium in soil and rock breaks down. It can move up through the ground and enter a home through cracks in slabs, crawlspaces, sump pits, utility penetrations, and other openings. Because you cannot see or smell it, testing is the only way to know whether a property has elevated levels.
Why testing for radon matters
Radon exposure is a health concern because it can build up indoors over time, especially in lower levels of a home. Basements and first floors are the most common testing areas, but radon can affect any structure depending on design, ventilation, and how it contacts the soil.
In Western North Carolina, radon testing is especially relevant. Soil conditions, mountain geology, and varying foundation types can all influence whether a home has elevated readings. One home may test low while the house next door tests high. That is why assumptions are not enough. Testing the specific property is what matters.
For buyers, a radon test can help avoid an unexpected issue after closing. For sellers, it gives you a chance to address concerns early and keep the transaction moving. For current homeowners and landlords, it is a practical way to check an invisible risk and decide whether mitigation is needed.
How to test for radon: the two main options
There are two general ways to test for radon: with a do-it-yourself kit or with a professional test performed by a qualified inspector. Both can provide useful information, but they are not identical in accuracy, control, or documentation.
Short-term radon tests
Short-term tests are the most common starting point. These usually remain in place for about 2 to 7 days, depending on the device. They are designed to give a quick snapshot of radon levels, which makes them useful during real estate transactions when timing matters.
Short-term testing is practical, but it has limits. Radon levels can change from day to day based on weather, pressure, HVAC operation, and how the home is used. A short-term test does not capture every fluctuation. It gives you a useful reading for a specific period, not a year-round average.
Long-term radon tests
Long-term tests typically run for more than 90 days. Because they measure over a longer period, they provide a better picture of average exposure. This can be especially helpful if you are not working under a contract deadline and want a more complete view of conditions in the home.
The trade-off is simple: long-term tests usually offer better overall context, but they take longer to complete. If you need fast answers before closing, a short-term professional test is often the more practical choice.
Where to place a radon test
Placement matters more than many people realize. A radon device should be placed in the lowest livable area of the home. That means the lowest level that is regularly occupied or could reasonably be used by occupants. In many homes, that is the basement. In others, it may be the first floor if there is no basement.
The device should not be placed in a kitchen, bathroom, laundry room, closet, crawlspace, or unfinished area that is not used as living space unless the test protocol specifically calls for it. It should also be kept away from drafts, exterior doors, windows, direct sunlight, high humidity, and strong airflow from vents or fans.
Proper placement helps reduce false readings and gives a result that better reflects the air people are actually breathing. This is one of the reasons professional testing can be valuable. The test itself may look simple, but setup conditions matter.
Preparing the home for a valid radon test
If you want reliable results, the home needs to be prepared correctly before and during the test period. For most short-term tests, closed-house conditions are required. That usually means keeping exterior windows closed, using outside doors only for normal entry and exit, and avoiding whole-house fans or other conditions that could artificially change indoor air pressure.
Heating and air conditioning systems can typically run normally if they recirculate indoor air. What you want to avoid is anything that brings in large amounts of outside air in a way that could skew the reading.
This is where mistakes often happen with DIY kits. The kit may be sound, but if the home was not kept under proper conditions, the result may not tell the full story. In a real estate setting, that can create delays, retesting, and unnecessary uncertainty.
DIY kit or professional radon test?
A DIY kit can make sense if you are testing your own home on your own timeline and you are comfortable following the instructions exactly. It is often the lower-cost option, and it can be a reasonable first step for general screening.
A professional radon test is usually the better fit when the result will affect a home sale, negotiation, repair decision, or documentation for clients and agents. Professional testing offers more control over placement, timing, and reporting. Depending on the equipment used, it may also include features that detect tampering or environmental changes during the test period.
That added oversight matters when the stakes are higher. Buyers, sellers, and real estate professionals usually want a result that is well documented and easier to rely on when decisions need to be made quickly.
Understanding the results
Radon is measured in picocuries per liter of air, written as pCi/L. The Environmental Protection Agency action level is 4.0 pCi/L. If a home tests at or above that level, mitigation is generally recommended.
That said, radon risk is not an all-or-nothing issue. Even levels below 4.0 pCi/L may still warrant attention depending on the situation and the homeowner’s comfort level. Some people choose to reduce levels that are below the action threshold, especially if they plan to stay in the home long term.
If a short-term test comes back high, the next step may be a follow-up test or a direct conversation with a qualified radon professional about mitigation options. The right response depends on the reading, the type of test used, and whether you are in the middle of a transaction.
When to retest for radon
One test does not always mean you are done forever. Retesting is a good idea after major renovations, after installing a mitigation system, after changes to HVAC or foundation conditions, or if you start using a lower level of the home more frequently.
It is also reasonable to retest periodically even if a previous result was acceptable. Homes change over time. Soil moisture, settling, air leakage, and ventilation patterns can all affect indoor radon levels.
If you are buying a home that was tested years ago, it is smart to test again rather than rely on an older report. A past result is helpful background, but it should not replace current testing.
What happens if radon levels are high?
A high reading does not mean the deal is over or that the home is unsafe to buy. In many cases, radon can be reduced effectively with a mitigation system. These systems often use vent piping and a fan to draw radon from beneath the home and discharge it safely outside.
The key is getting reliable test data first. Once you know the level, you can make an informed decision about next steps, costs, and timing. That is far better than guessing.
For homeowners, this can mean improving long-term indoor air safety. For buyers and sellers, it often means moving forward with clearer expectations and better documentation.
A practical approach to how to test for radon
If you want the most practical path, start by considering your goal. If you simply want a general check and have flexibility, a carefully handled long-term or DIY screening test may be enough. If you are under contract, need dependable reporting, or want stronger confidence in the process, a professional radon test is usually the better choice.
At Home Remedy, radon testing is part of helping clients make confident property decisions with clear information, not guesswork. Whether you are evaluating a home before purchase or checking the one you already own, a properly conducted test turns an invisible concern into something you can actually address.
The most helpful next step is often the simplest one: test the home you are responsible for, and let the result guide what comes next.