Solved: Where To Place a Radon Test For Accurate Results

Radon is an invisible gas that can enter through small cracks and crawl spaces. You cannot see it or smell it. The EPA links radon to about 21,000 lung cancer deaths in the United States each year. The good news is that smart testing and correct detector placement give you clear answers fast.

Testing works best when you choose the lowest-occupied level and a room you actually use. That gives you an accurate picture of what you breathe every day, not just a number from a corner you never visit. If your family spends evenings in a finished basement or a first-floor family room, start there.

Short-term tests require closed-house conditions to be accurate. Keep exterior doors and windows closed for 12 hours before and during the test. Run the HVAC as usual. Avoid significant changes, such as deep cleaning with open windows or running whole-house fans.

Key Takeaways

• Test on the lowest level first.

• Use a room you spend time in, such as a bedroom or family room.

• Avoid kitchens, bathrooms, and laundry rooms.

• Set the device at least 20 inches above the floor.

• Please keep it away from windows, doors, and vents.

• Retest after mitigation or significant renovations.

Best Placement

Start on the lowest level where you live. This is where radon tends to be highest. Use a finished basement or the first floor that people actually use. If you have a crawl space, test a room directly above it as well.

Choose a frequently used room. Bedrooms and living rooms reflect real exposure because you spend the most time there. Avoid closets or storage rooms that do not represent daily breathing zones.

Rooms To Avoid

Skip the kitchen, bathroom, and laundry room. Moisture, steam, and strong airflow can distort readings. That can either hide a real problem or make one look worse than it is.

Simple Placement Rules

• Height: at least 20 inches above the floor.

• Distance: at least 3 feet from doors and windows.

• Walls: at least 1 foot from exterior walls and away from visible cracks.

• Airflow: keep clear of vents, fans, heaters, and direct sunlight.

• Clearance: leave a few inches of open space above and around the device.

• Closed house conditions: keep exterior doors and windows closed 12 hours before and during a short-term test.

Quick Reference Table

Common Mistakes

• Setting the device on the floor.

• Placing it near drafts or heat sources.

• Opening windows during the test period.

• Forgetting to return a charcoal kit right after the test ends.

• Skipping a retest after installing a mitigation system or finishing renovations.

• Ignoring the manufacturer’s directions.

What To Do Next

1. Pick the lowest level you live in and a room you use often.

2. Place the detector using the rules above.

3. Run the test for the recommended time.

4. If results are 4.0 pCi/L or higher, plan mitigation.

5. Re-test after the system is installed to confirm results.

A few smart choices about where you place the device can turn a guess into a confident answer.

TL;DR

Test where you actually live and breathe. Start on the lowest level in a room you use often, such as a bedroom or family room. Keep the device about 20 inches off the floor and away from windows, doors, and vents. Skip kitchens, bathrooms, and laundry rooms. For short-term tests, keep exterior doors and windows closed for 12 hours before and during the test. If your result is 4.0 pCi/L or higher, plan mitigation and retest after the system is installed. A few smart placement choices turn guesswork into a clear answer.