Radon testing: what to know

What the job involves, what changes the price, and what to ask a pro.

What radon testing is

Radon testing measures radon gas in a building. A tester places a device for a set period, then sends it to a lab or reads the result and explains what it means. Radon is a naturally occurring gas that can enter a home from the soil, so testing is the only way to know the level in a given house.

Signs you need it

  • You are buying or renting a home, and you want the radon level recorded before you commit
  • You live in a basement or a ground-floor room that is used regularly, and you have never tested
  • Your home has a crawl space, a sump pit or cracks in the foundation that may let soil gas in
  • You have made changes to the home, such as a new foundation repair, a new basement finish or sealing work, and want to recheck
  • Your local health office or a neighbor has reported radon issues in your area

What the pro does

  • The tester explains the test type, such as a short-term or long-term device, and the period it will run
  • They place the device in the lowest lived-in level of the home, away from drafts, heat sources and high humidity
  • They record the start and end times and the closed-house conditions the test needs
  • They collect the device after the test period, or the lab collects it, and check that the device is sealed and labeled
  • They send the device to an accredited lab, or read a continuous monitor and work out the level for the period
  • They deliver the result with an explanation of the level and the next steps, such as a follow-up test or a mitigation contractor

What changes the price

Every job is different, so we do not publish prices. These are the things that move the quote up or down.

  • Type of test, such as a short-term device, a long-term device or a continuous monitor
  • Number of devices placed, including a second test in a different room or level
  • Lab fees for the device, which depend on the lab and the turnaround
  • Whether the tester visits to place and collect the device, or the test is mailed
  • Whether the report includes a written explanation and a recommended next step
  • Whether a confirmatory test is included after a high first result
  • Real estate timing, such as a rush result needed before closing

What a written quote should spell out

  • Test type and the period the device will run
  • Number of devices and where each one will be placed
  • Lab name, accreditation and turnaround time
  • Closed-house conditions the test requires, and who explains them to you
  • Written report with the result, the date and an explanation of the level
  • Follow-up test included or priced separately if the first result is high

Questions to ask before you hire

  • What type of test are you using, and how long does it run?
  • Which lab analyzes the device, and is the lab accredited?
  • Where will the device be placed, and why there?
  • What do I need to do during the test to keep the results valid?
  • If the result is high, what is the next step, and do you offer a follow-up test?
  • Are you certified or accredited as a radon tester in this state, and can I check that?
  • When will I get the written result, and can it be shared with a buyer or lender?

Red flags

  • They offer a test that runs for a few hours and call it a complete reading for the home
  • They place the device in a closet or a drafty spot and do not explain why
  • They pressure you to buy a mitigation system in the same visit, before the result is confirmed
  • They do not identify the lab or do not show the lab's accreditation

What you can do yourself

You can buy a radon test kit from a retailer and follow its placement and sealing instructions, and place the device in the lowest level you use. Keep windows and doors closed as the kit directs, and send it to the lab named on the kit. Do not place a device near a fan or a vent, and do not try to reduce a high reading yourself. Call a licensed radon mitigation contractor if the result is high.

Licenses and permits

Radon testing is often done by a certified or licensed radon professional, and some states require a license or certification for radon work. Check with your state radon or health office for the rules on testing and for who must sign or certify a test result used in a sale.

Radon testing questions

How long should a radon test run?

Short-term tests run for a few days, and long-term tests run for much longer. Ask the tester which test fits your situation, since the length changes how the result should be read.

Does a radon test in one room show the level for the whole house?

It shows the level in the place tested, under the conditions of the test. Levels can differ between floors and rooms, so ask whether a second device should be placed in another area.

What happens if the radon result is high?

Ask for a follow-up test to confirm the level, and talk to a licensed radon mitigation contractor about the options. Mitigation is usually a system that vents soil gas outside, not a fix you can do by sealing cracks alone.

About this guide

This national guide is written and checked by infinibell. Rules and conditions differ by place, so local pros are credited on guides for the cities they serve, not on national ones.

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