Where Should a Radon Test Be Placed in a Home?

Radon test placement matters. A device should be placed where it can measure indoor radon without being affected by drafts, heat, humidity, exterior walls, or unusual air movement.

Which Level of the Home Should Be Tested?

For many residential situations, testing is performed in the lowest level that could be regularly occupied. That may be a finished basement, an unfinished basement that could become living space, or the first floor of a slab-on-grade home. The correct placement depends on the property and the purpose of the test.

How High Should the Device Be?

EPA guidance for short-term testing says the device should be placed at least 20 inches above the floor.

Where Shouldn't a Radon Monitor Go?

• Next to an exterior door or open window
• In direct drafts
• Near high heat
• In areas of high humidity
• Where someone may disturb or move it
• Directly against an exterior wall

What About Bedrooms or Living Rooms?

The goal is to measure an appropriate regularly occupied area of the lowest suitable level, not simply whichever room is easiest to access. A qualified measurement professional evaluates the home layout before placement.

Why Professional Placement Helps

Real-estate deadlines and property decisions can depend on the test result. Professional placement reduces avoidable setup errors and documents where the monitor was located during the measurement.

EPA Source

EPA Home Buyer's and Seller's Guide to Radon

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General educational information only. For current federal guidance, see the U.S. EPA radon resources linked on this page.