Where Should a Radon Test be Placed?

Learn more about our home radon test kits here.

Home radon testing is the best way to protect you and your family from unnecessary lung cancer risks. While our home tests are easy to use and come with complete instructions, it is helpful to know where radon tests should be placed before they make a purchase. These tips on the best placement of detector kits will prepare you for the process and assure you that it's easy to handle on your own. Regardless of why you need to test for radon or the layout of your home, here's what you need to know about radon test placement.

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Recommended Placement of the Detectors

Our radon tests are highly accurate and easy to use, but placement is important for getting correct readings. Making a mistake could give you a false negative reading, letting you believe you're breathing in safe air while you're actually inhaling unsafe levels of radon.

  • Place at least one test kit in the largest central living area on the lowest occupied level of the home that receives air flow from the rest of the space.

  • You may want to also test the floor you occupy the most to see if and how your radon level is dissipating as it moves from floor to floor. This gives you a general reading of the home's entire air supply.

  • Place a test in a room or floor if you are concerned about radon in a specific area. However, a specialized test focused on one room or floor isn't a replacement for a general test in a central area.

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Common Mistakes to Avoid When Placing a Radon Test

Even with complete radon test kit placement instructions, the most common problems come from small oversights during setup. Knowing what not to do and how to avoid radon test errors is just as important as knowing how to place a radon test kit correctly. Missteps can throw off your radon test results and leave you with readings that don’t reflect your true exposure.

Below are the most frequent mistakes homeowners make.

  • Placing the detector near windows, doors, or vents
    Drafts and HVAC airflow dilute radon concentration, often creating a reading that looks safer than it really is. This mistake can leave you with the impression that your air is healthier than it truly may be.

  • Testing too close to known radon entry points
    Locations such as sump pits, foundation cracks, or exposed crawl spaces can lead to higher radon levels that don’trepresent what your family typically breathes in living areas. Testing here creates skewed results that exaggerate the true risk.

  • Using sealed-off or rarely used areas
    Placing a detector in storage rooms or unoccupied basements does not reflect real daily conditions. These areas don’t provide a reliable picture of your lived environment and can create misleading outcomes. Test in regularly occupied spaces instead.

  • Ignoring height and distance guidelines
    Tests should be positioned 20 inches above the floor, two feet below the ceiling, and at least three feet away from doors or windows (ANSI/AARST standards). Skipping these details is one of the most frequent mistakes to avoid when placing radon detector devices and can reduce accuracy.

  • Opening the pouch too early
    A radon test kit activates the second it is unsealed. Starting prematurely or moving it after activation can compromise accuracy, which is why reviewing radon test setup directions beforehand is so important.

  • Overlooking household activity
    Curious pets or children may bump or relocate the device, which can spoil your measurement. Hanging the detector on a hook or keeping it in a secure location helps prevent disruptions.

Download the Home Radon Test Checklist

Additional Information for Your Radon Test

Radon test placement tips:

  • Is your basement occupied? Make sure you're including it in your radon testing area. Place at least one test in the lowest area of the home used on a regular basis. If you have a large home, you may want multiple detectors to obtain radon levels in different areas of the home.

  • Radon can enter your home through areas at ground level or above a crawl space, so you’ll want to test these areas in addition to your basement.

  • Place the test kit on a shelf or table against an interior wall that is free from ventilation sources like vents or air returns. Keep the test at least three feet away from all windows, doorways, and exterior walls. Placing the test in a draft or near a window introduces too much fresh air to accurately measure your indoor air levels. Going in and out of the house won't hurt, but for short term measurements, QuickScreen and Rapidos, keep windows closed during the test period for accurate readings.

  • Place the test at least 20 inches above the floor and two feet below the ceiling. Make sure pets, children, and family members can't move it or play with it.

  • "Should I hang the radon detector?" It's not necessary, but it is easy thanks to the hook built into the top of our detectors. The results will be the same as long as you follow the placement tips. This is a great option if you're lacking free table space or need to keep the tests away from curious pets.

  • Installing the detector is as simple as removing it from the airtight packaging and placing it. The test becomes active immediately upon opening, so do not open the plastic pouch until you are ready to begin your test. When the test period is complete, pack the test up in the pre-addressed mailer and send it off to our labs.

Frequently Asked Questions

It’s best to wait until construction is complete. Home renovations like tearing out walls, replacing flooring, or updating HVAC systems can disrupt airflow and temporarily change radon behavior. For the most accurate reading, follow ideal conditions for radon testing by waiting until ventilation patterns have returned to normal.

Yes. Winter is often the best season for radon detector readings because homes are sealed tight and any radon entry is more pronounced. Higher radon levels are often detected during colder months, giving you a more conservative measure of your exposure. Testing in summer is still valid but may produce slightly lower numbers.

No. While radon may collect in crawl spaces or closets, these are not areas where people spend significant time. Following where should radon test be placed guidelines is key—detectors should be located in commonly occupied rooms like living rooms, bedrooms, or dens, not hidden storage areas.

Testing during use can distort results. Fireplaces and stoves create negative pressure that can pull radon in from the soil, producing an artificially high reading. For reliable radon test results, pause wood stove or fireplace use during short-term testing.

If the device shifts only slightly, your reading may still be valid. But if it’srelocated significantly, retesting is recommended. To avoid this problem, follow your radon test placement guide and keep the unit in a stable, undisturbed spot.