How Homeowners Prepare for a Radon Inspection

One inspection homebuyers can perform is a radon test. Radon is a naturally occurring radioactive gas that comes from the breakdown of uranium in soil and rock. While the health effects of radon exposure can be debated, radon is invisible, odorless, and tasteless and can only be detected through testing.

How is Radon Tested

Usually the radon inspection is an add-on to the home inspection with the home inspector bringing a radon testing device, which looks like a small box or canister—about the size of a lunchbox. This device is usually placed in the lowest livable level of the home in the living room.Typically the testing advice is set on a table, shelf, or stand in a central area—not in kitchens, bathrooms, or laundry rooms, since humidity can affect results.

Home Homeowners Prepare

12 hours prior to the Radon Test, homeowners should make sure the following are adhered:

1. Close all windows and exterior doors

2. Set heating and cooling systems to normal operation with temperatures between 60F and 80F

3. Set seasonal systems that temporarily ventilate with outdoor air to lowest settings

4. Turn off whole house fans

5. Avoid operating exhaust fans for laundries, workshops and kitchens

6. Do not operate fireplaces

Test Duration

The radon testing device will run for 48 hours. The testing device continuously monitors radon levels during that time. Some modern units also record temperature, humidity, and air pressure to verify that testing conditions were maintained.

Pick-Up and Lab Analysis

After 48 hours, the inspector returns to pick up the device. If it’s a digital monitor, the results are downloaded immediately. If it’s a charcoal canister or other passive device, it’s sent to a certified lab for analysis.Most inspectors provide results within 24–48 hours after the device is retrieved.

Report and Next Steps

The Homebuyer will receive a written report showing the average radon level (measured in picocuries per liter, or pCi/L).

• If levels are below 4.0 pCi/L, no action is typically required.

• If levels are 4.0 or higher, the Buyer's Agent may request a radon mitigation system—a simple and effective fix that vents the gas outdoors.

Installing a mitigation system is typically a straightforward process that involves adding a vent pipe and fan to draw radon from beneath the home. Most systems cost between $1,000 and $1,500 and can reduce radon levels by up to 99%.

Follow-Up Testing

After mitigation, the home buyer may want to perform a follow-up test to ensure the system is working properly and that radon levels remain low.