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.
Plumbing stacks may run inside the walls of your home, from the basement to the attic, with openings at each floor where the pipes branch off. Use the piping runs in the basement to help you locate holes. Plug the bottom and top of the chase with foam caulk or 6ml polyethylene.