House Detective: Making the Most of Home Inspection

The House Detective by Barry Stone, Certified Home Inspector

Dear Barry: We are planning to sell our home and have learned that we have high levels of radon. Is there an inexpensive way that we can solve this problem before we list the property? And why do some homes in our neighborhood have high radon levels while other homes do not? Ann

Dear Ann: Radon mitigation is a fairly simple process for a qualified contractor, and in most cases is not terribly expensive — usually about $1500. To understand why one home will have high radon levels, while the next-door property does not, let’s review some radon basics.

Radon is a radioactive gas that is emitted from certain types of rocky soil and is naturally diffused into the environment. If the soil is covered by a building, such as your home, radon can become trapped and may reach higher concentrations than normally found in the open air. In homes with raised foundations, radon is seldom a problem because subarea vents allow radon to escape into the atmosphere. In homes with concrete slab foundations, hairline cracks in the slab enable radon to enter the dwelling space where concentrations can increase to unsafe levels. This poses a health risk for occupants because radon exposure has been linked to lung cancer.

The key to radon mitigation is the fact that radon gas is attracted to low-pressure areas. Radon mitigation contractors take advantage of this characteristic in the following manner: A metal duct is installed near the center of the home, in an inconspicuous place such as a closet. The duct extends from beneath the slab to just above the roof. A slow, quiet fan motor is installed in the duct with an upward draft, creating low-pressure suction beneath the slab. This suction draws nearly all of the radon that is emitted from the soil beneath the home and conveys it to the exterior where it dissipates into the atmosphere. Once this is done, your home should be able to pass a standard radon test.

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