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Radon Mitigation Systems
If you've tested your home for radon and found elevated radon levels greater than 4 picocuries per liter (4 pCi/l), you should confirm those levels with a follow-up test. If the test results are confirmed, you should take action to reduce exposure to radon. This may mean simply changing your occupancy patterns. For example, you can spend less time in the basement if levels down there exceed the guideline but levels on the first floor are acceptable. Ultimately, your best option is to take action to prevent or reduce how much radon is entering your home. This way you don't have to worry about where you spend your time in your home.
Some of the first steps you can take to reduce radon entry is to caulk and sealing entry points. You can caulk and seal the floor/wall joint; sump openings; cracks in the floor or walls; space around plumbing, wiring or ductwork; and/or openings at the top of a hollow block wall. Unfortunately, caulking and sealing is rarely adequate as a stand-alone mitigation option. To get guaranteed results, a trained contractor can be hired to install a radon mitigation system. Almost any radon level, regardless of how high it is, can be brought down to below the 4 pCi/l recommended action level.
Most radon mitigation systems are made of series of pipes and fans that remove radon vapors from under your foundation and exhaust them above the roof where it's safe. This type of system is also referred to as an active soil depressurization system because it reduces the pressure under the house, so radon gas is no longer being pushed in through openings in the foundation. Radon mitigation systems generally start with a four-inch plastic pipe that goes down through the foundation floor and runs up and out of the house as shown here in the picture and linked video. A small in-line fan is attached to draw radon vapors from under the foundation or slab into the pipe, then up and out the pipe at the roofline.
Radon mitigation systems designs vary from home to home. Some contractors take advantage of existing sump openings and fit them with a special cover, then run the PVC pipe down into that hole. Other contractors may drill a four-inch hole through the cement floor and dig out a pit about the size of a five-gallon pail. Others may tie into an existing drain tile. When dealing with crawlspaces, a plastic vapor barrier is needed. The barrier is needed for the system to capture and pull the radon vapors from under the plastic barrier and prevent them from entering the home. Most systems are designed for the pipe to exit the interior of the house just above ground level. A fan is mounted on the outside of the home, then the exhaust stack runs up the side or back of the house to just above roof level, exhausting the radon gas away from any windows or openings that could draw the radon back into the home.
Nationally the price of a home radon mitigation system ranges from approximately $500 to $2,500. Here in Michigan a radon mitigation system generally costs between $800 and $1,500, depending on where you are in the state and who you hire. The systems can usually be installed in a day or less, and a reputable contractor will provide a guarantee that the system will achieve results below 4 pCi/l. Often the systems can achieve results below 2 pCi/l.
Michigan does not license or regulate radon testing and mitigation contractors. So, a person who is trained and certified by one of the two national organizations that offer certification for testers and mitigators, should be used. The National Radon Proficiency Program or the National Radon Safety Board both maintain a list of certified contractors on their websites at https://nrpp.info/ and www.nrsb.org. A list of certified contractors can also be obtained from your local health department, or by calling the Michigan Department of Environment, Great Lakes, and Energy (EGLE) Indoor Radon Program at 800-RADON GAS (800-723-6642).