Testing Guideline

Closed Building Conditions

Pre-Existing Homes

Closed Building Conditions are required for any testing period shorter than 7 days.

A 48 hour test can only be done if the Closed Building Conditions are met and maintained for 12 hours prior to the start of the testing period. If the conditions have not been met prior to the testing period, the minimum 48 hour test will be extended to be a minimum of 60 hours.

Closed Building Conditions must be maintained 12 hours prior to deployment of testing equipment and until retrieval of equipment by a State of Illinois licensed radon professional.

  • All windows (all the windows on all the floors) in the home must be kept closed.
  • All exterior doors must be kept closed except for normal entry and exit.
  • Heating and Air-Conditioning systems may be used with the fan in the auto mode.
  • Whole house fans shall not be used.
  • Ceiling fans, portable dehumidifiers, and air filter should not be used within 20 feet of testing equipment.
  • Fireplace can not be used during the testing period and the flu damper should be kept closed.
  • Dryers, range hoods, and bath exhaust fans can only be used in moderation.
  • If the home has a radon mitigation system, it must be functional for at least 24 hours prior to and continuously during the testing time.


New Construction Homes

At the end of the building process, everyone is ready to get to closing. Testing during this time can be tricky. We cannot test too early, and the later in the construction it gets, the more frenzied the pace around the house and the less likely the builder will be able to keep the site closed building conditions maintained for long enough to complete a test. We strongly recommend performing new construction tests after the closing, either under the protection of the builder warranty or with specific funds held aside in escrow for mitigation pending the results of the post-closing test.

If that is not possible, here is what must be completed before a test can be performed at the property:

  • All insulation must be installed
  • All exterior doors with associated hardware must be installed
  • All windows must be installed
  • All fireplaces and fireplace dampers must be installed and closed
  • All heating, air-conditioning, and plumbing appliances must be installed and functional
  • All ceiling covers must be installed
  • All interior trim and coverings for the exterior walls must be installed
  • All exterior siding, weatherproofing and caulking must be completed
  • All interior and exterior structural components must be completed
  • Water, gas and electric services must all be functional