How to Prepare Your Home for Radon Testing in Philadelphia

What Philadelphia homeowners should—and shouldn't—do before a professional radon test.

If you’re scheduling a professional radon test for your Philadelphia home, you might be wondering how to prepare. Should you open the windows to air things out? Clean out the basement? Turn off the HVAC? Move furniture or hide clutter?

The good news is that preparing for a professional radon test is simple. In most cases, the best thing you can do is keep your home operating as it normally would. The goal is to measure your home’s radon level under typical living conditions—not after you’ve tried to change the result.

Philadelphia-area homes—including rowhomes, twins, townhouses, and single-family homes—can all have elevated radon levels regardless of their age, foundation type, or neighborhood. Proper preparation helps ensure your test reflects the home’s actual conditions. If you’re new to radon, you may also want to read our guide explaining what radon is and why testing matters.

Here is everything you need to know before your radon measurement professional arrives.

1. Maintain Your Daily Routine

The best preparation is simply sticking to your daily routine while following any closed-building instructions provided by your radon measurement professional.

You do NOT need to:

• Deep-clean or stage the house

  
  

• Rearrange your basement or clear every surface

  
  

• Open windows to "air out" the property beforehand

  
  

• Run fans specifically to drive down radon levels

  
  

• Change your standard heating or cooling schedule

  
  

Intentionally changing your home’s environment immediately before or during testing can influence the measurement and may prevent the results from accurately representing normal living conditions. For a short-term test, your tester will help establish closed-building conditions and guide you on maintaining them.

2. The Rule on Windows and Doors

Before the Test

Opening windows before or during a short-term radon test changes the home’s normal air movement and pressure relationships, which can affect the validity of the measurement. Maintaining closed-building conditions helps ensure the test reflects the home’s typical radon levels.

Did someone leave windows open? Don't stress or try to fix it yourself. Just let your tester know when they arrive so they can evaluate the conditions and document them properly.

During the Test

Once deployment begins, the home must remain under closed-building conditions. Avoid:

• Leaving windows cracked

  
  

• Propping exterior doors open

  
  

• Operating whole-house attic fans

  
  

• Intentionally airing out lower levels or basements

  
  

Note: Normal entry and exit through exterior doors is expected. You don't need to lock yourself inside for two or three days!

Why do these instructions matter? Radon levels naturally rise and fall throughout the day due to weather, barometric pressure, and how a home exchanges air with the outdoors. Following testing instructions helps reduce unnecessary variables so the measurement better represents the home’s typical conditions.

3. How Long Before a Radon Test Should Windows Be Closed?

For most professional short-term radon tests, including those performed during real estate transactions, closed-building conditions generally begin at least 12 hours before the test starts and continue throughout the testing period, consistent with applicable testing protocols. Your measurement professional will explain the specific requirements for your situation.

4. Can I Leave the House During a Radon Test?

Yes. You can continue your normal daily activities, including going to work, running errands, and leaving the home. Simply avoid making changes that affect the home’s ventilation, such as leaving windows open or operating whole-house fans.

5. Do I Need to Clean or Move Anything?

No. A radon test isn't a white-glove home inspection. The tester is measuring radon levels, not judging your housekeeping.

Your tester will select an appropriate location based on the home’s layout, foundation, and applicable testing protocols—typically on the lowest level suitable for regular occupancy, such as a finished basement or first floor. Just ensure there is a clear, accessible path to the testing location.

Testing devices are placed according to established measurement protocols—not simply wherever there is available space—to help ensure accurate and representative results.

6. Tell Your Tester About "Unusual" Conditions

Communication is one of the most critical parts of an accurate test. Before placement begins, notify your tester if any of the following apply:

Structural, Mechanical & Environmental Conditions	Property & Transaction Status
• HVAC, dehumidifiers (if unusually used), or fresh-air/ERV systems	• The home has been vacant recently
• Active radon mitigation system present	• Property is involved in a real estate sale
• Crawl space access changes or sump pit recently sealed/opened	• Active renovations are currently underway
• Large exhaust fans used regularly or recent power outages	• Windows or doors that don't seal properly
• Recent foundation work or basement water intrusion	• Previous unexpected radon test results

Sharing these details doesn’t automatically delay or cancel the test. It allows your measurement professional to determine whether any adjustments or documentation are needed to maintain testing quality.

7. Don't Disturb the Testing Equipment

Once devices are placed, leave them completely alone.

• Do not: Move devices to another room, cover them, place furniture against them, or unplug associated monitoring equipment.

  
  

• Pets & Kids: Keep pets secured during the tester's arrival and ensure children and animals cannot disturb the device while testing is active.

  
  

If a device is bumped, knocked over, or moved by accident, simply inform your tester so it can be logged in the final report.

Pre-Test Checklist for Homeowners

• [ ] Maintain your normal thermostat and living routines.

  
  

• [ ] Keep exterior windows and doors closed starting at least 12 hours prior to deployment (except for normal entry/exit).

  
  

• [ ] Ensure clear access to the lowest livable area or basement.

  
  

• [ ] Secure pets prior to the tester's arrival.

  
  

• [ ] Note any unique mechanical systems, crawl space changes, or recent property work to tell your tester.

  
  

• [ ] Leave deployed equipment untouched until retrieval.

  
  

What Happens After the Test?

When testing ends, the equipment is retrieved and submitted to an accredited laboratory for analysis before your final report is prepared.

If your results show an elevated radon level, don’t assume the worst. Elevated results are not uncommon, and they don’t mean your home is unsafe to occupy immediately. They simply indicate a long-term indoor air quality issue that can usually be addressed with a properly designed mitigation system.

Schedule Professional Radon Testing in Philadelphia

Whether you’re preparing for a real estate transaction or testing your current home, Liberty Radon Diagnostics delivers independent, unbiased radon measurements throughout Philadelphia and nearby communities. Because we don’t perform mitigation, our recommendations are based solely on accurate measurement—not selling repairs.

Ready to schedule professional radon testing in Philadelphia? Contact Liberty Radon Diagnostics today to book your appointment.

About the Author

Moises Serrano is the owner of Liberty Radon Diagnostics LLC, an independent radon measurement company serving Philadelphia and surrounding communities. Liberty Radon Diagnostics performs radon testing and diagnostics only and does not install mitigation systems, allowing for unbiased measurement results.