How Radon Mitigation Works

Removes Radon Before
It Enters the Building

To remove radon, reduce radon, or get rid of radon is called radon mitigation or radon remediation. By far the most common radon mitigation technique is called active soil depressurization. The process involves suctioning the soil and radon gas from under the floor of the lowest level of a building. A fan sits outside the living area and is connected to a hole in the floor by PVC piping. The fan discharges radon gas above the roof edge. Sizable openings in the floor, such as cracks and sump pits, are sealed to ensure adequate suction.

Radon mitigation systems are permanent to the building and run 24/7. Typically, the goal is to reduce radon levels to below 4.0 picocuries per liter of air. The systems can vary in price from $1,100 to $6,000 each, with most systems in the $1,500 – $2,500 range.

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Most companies use a small number of these options while DuPage Radon Contractors uses any which may best fit your situation. Regardless of the company, the radon mitigation system process needs to be custom-designed to each situation based on building layout, regulations, and aesthetic considerations. Passive systems without a fan are an option for new construction – read about them here.

Fan Options

The fan sits outside the inhabited space, usually on an outside wall or in an attic. It can be covered, exposed, or low-profile. Fan life is typically between 5 and 25 years, with most lasting 7 to 12 years. DuPage Radon Contractors offers all four fan options.


Electrical for the fan is tapped off of existing circuits or a new circuit is run. Most fans use between 20 and 120 watts of electricity, so it is typically not a taxing load onto an existing circuit. The fan electrical usage operating costs are about $30-$130 a year.

Suction Points

From the fan, piping is run to the areas needing suction. The end of the pipe is called a suction point. The pipe might pierce the concrete floor of a basement, crawlspace, or slab main floor, or it may suction from under a membrane that is placed over a gravel-floored crawlspace or through a foundation wall to access the gravel layer under an adjacent concrete floor. The pipe is made of Schedule 40 gauge, DWV, PVC piping, which is the same piping commonly used for plumbing drains.

Suction Points

Buildings with multiple foundation types, such as basements, crawlspaces, and slab-on-grades require radon mitigation methods that incorporate multiple suction points with pipes connecting them to the fan. Usually, one fan is sufficient for a home.

Gravel & Dirt

Crawlspaces with gravel or dirt floors need a membrane to contain the suction. This membrane is usually 6 mill polyethylene sheet plastic spread over the entire crawlspace floor and sealed at the edges. The suction point then ends between the plastic and the gravel or dirt. DuPage Radon usually adds a layer of tar paper under the plastic to help protect the plastic from puncture.


The pipe above the fan is called the discharge, and can be made of PVC pipe or oversized aluminum downspout. Depending on the location of the fan, it may be mounted on the outside wall discharging above the roof or it may pierce the roof and discharge there. DuPage Radon Contractors can utilize any of these options.

Open Topped

The tops of all discharges are open to the sky. In the Chicagoland area, any grills or debris covers or tilting of the top has proven to increase ice build-up in the winter. The wind of the exhaust keeps most leaves and debris out. Any entering water is funneled back under the concrete slab floor and usually thereon to the sump pump. Occasionally, large debris or squirrels may need to be removed.

Sealing Floor

For the optimal radon mitigation system design, major floor cracks that are easily accessible are caulked to reduce air leakage into the system. There is generally no need to remove carpet or move washer/dryer for small cracks. DuPage Radon uses a very elastic clear caulk for durability and aesthetics.

Sealing Sump

Since the storm drainage system and sump pit are open to the gravel layer below the floor, the sump pit needs to be sealed. A special cover is installed, or an existing cover can be modified to meet newer regulations. The cover can be removed for access to the pump, but the lid must be caulked upon re-installation. DuPage Radon covers also allow visual inspection of the sump through a clear window.

and Alarms

The gauge that is typically installed to indicate if suction is occurring, is called a u-tube. It is recommended that you check this u-tube weekly. To avoid the need for regular checks, an airflow alarm can be added to the system to alert you of any issues with suction. Neither device, however, measures radon.


Most radon mitigation systems are relatively easy to design and install for professional mitigators. However, several situations can make for real challenges that increase the price and the need for a truly experienced mitigator. Read more about what defines a “Tough Case” here.

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