How do you install a radon mitigation system in a basement?

Get it in writing. Ask for a contract before any work starts, covering the total cost with taxes and permit fees, the time needed to complete the work, an agreement to obtain permits and follow building codes, and whether any warranties transfer if you sell the home.

Most basement systems are active subslab suction, the most common and usually the most reliable radon reduction method. The steps below follow the usual order; your contractor's design decides the details.

1. 1

   Inspect and, if needed, run diagnostics

   The contractor looks the house over. If that is not enough, chemical smoke can show the source and direction of air movement, and a soil communication test, with a vacuum cleaner and chemical smoke, shows how easily air moves under the foundation.

2. 2

   Set the suction point

   One or more suction pipes go through the floor slab into the crushed rock or soil underneath; they can also go below the slab from outside the home. Often a single suction point is enough. In a basement with a sump, the sump can be capped and used as the suction point.

3. 3

   Run the pipe and mount the fan

   A radon vent fan connected to the pipes draws radon from below the home and releases it outdoors. Common fan locations are unconditioned home and garage spaces, including attics, and the exterior of the home.

4. 4

   Seal cracks and openings

   Sealing limits the flow of radon into the home, makes the suction more effective and cost-efficient, and reduces the loss of conditioned air.

5. 5

   Fit the warning device and label the system

   A warning device must alert you if the system stops working properly, and the system must be clearly labeled so nobody changes it by accident.

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1. 1Soil gas drawn from beneath the slab
2. 2Suction point through the slab
3. 3Vent pipe
4. 4Fan, outside the living space
5. 5Discharge above the roofline

A finished system should meet a short list of basic requirements, and the installation should follow the radon mitigation standard ASTM E2121. Your state may add its own rules. Use the table to check the work.

EPA recommends a qualified radon mitigation contractor, because lowering high radon levels requires specific technical knowledge and special skills. Many states require radon professionals to be licensed, certified or registered and to install systems that meet state requirements. Where a state does not regulate radon work, ask whether the contractor holds a proficiency credential and follows a standard such as ASTM E2121.

States that receive federal indoor radon grants keep a public list of providers credentialed by the state or by one of the two national radon proficiency programs, the National Radon Proficiency Program (NRPP) and the National Radon Safety Board (NRSB). Our mitigation directory lists professionals by state.

The install is proven by a test, not by the fan running. A two- to seven-day measurement is recommended, with windows and doors closed 12 hours before and during the test, and an independent follow-up measurement as well as any test the contractor does removes any conflict of interest.

Ask the contractor to explain the system, show how it operates and leave written operating and maintenance instructions and copies of any warranties.