Radon testing device(s) should be placed in the lowest level of the home suitable for occupancy. This means testing in the lowest level (such as a basement), which a buyer could use for living space without renovations. The test should be conducted in a room to be used regularly (like a family room, living room, playroom, den or bedroom); do not test in a kitchen, bathroom, laundry room or hallway. Usually, the buyer decides where to locate the radon test, based on their expected use of the home. A buyer and seller should explicitly discuss and agree on the test location to avoid any misunderstanding. Their decision should be clearly communicated to the person performing the test.
Whether you test for radon yourself or hire a state-certified tester or a privately certified tester, all radon tests should be taken for a minimum of 48 hours. A longer period of testing is required for some devices.
If you are planning any major renovations, such as converting an unfinished basement area into living space, it is especially important to test the area for radon before you begin. If your test results indicate an elevated radon level, radon-resistant techniques can be inexpensively included as part of the renovation. Major renovations can change the level of radon in any home. Test again after the work is completed.
Remember that extreme temperatures can build in an attic without proper ventilation, especially with a dark colored roof.