Radon Mitigation

NOTE: North Carolina does not regulate radon testing or mitigation.


What is a radon mitigation system?

A radon mitigation system is any system or steps designed to reduce radon concentrations in the indoor air of a building. The EPA recommends that you take action to reduce your home's indoor radon levels if your radon test result is 4 pCi/L or higher.


What are the benefits of radon mitigation?

The primary benefit is reducing the risk of developing lung cancer.  Standard radon reduction systems are usually effective within 24 hours and maintain low levels as long as the fan is operating.  Another potential benefit of these systems is reduced infiltration of moist soil air with the radon, which may reduce the humidity level in the basement of the home.  Homeowners should consider correcting a radon problem before making final preparations to sell a home.  This often provides more time to address the problem and find the most cost-effective solution.  In addition, the current occupants--not just the buyer's occupants--will reap the benefit of reduced risk.


What can be done to reduce radon in a home?

Your house type will affect the kind of radon reduction system that will work best. Houses are generally categorized according to their foundation design. For example: basement, slab-on-grade (concrete poured at ground level), or crawlspace (a shallow unfinished space under the first floor). Some houses have more than one foundation design feature. For instance, it is common to have a basement under part of the house and to have a slab-on-grade or crawlspace under the rest of the house. In these situations a combination of radon reduction techniques may be needed to reduce radon levels to below 4 pCi/L.

There are several methods that a contractor can use to lower radon levels in your home. Some techniques prevent radon from entering your home while others reduce radon levels after it has entered. the EPA generally recommends methods that prevent the entry of radon.

In many cases, simple systems using underground pipes and an exhaust fan may be used to reduce radon. Such systems are called "sub-slab depressurization," and do not require major changes to your home. These systems remove radon gas from below the concrete floor and the foundation before it can enter the home. Similar systems can also be installed in houses with crawl spaces. Radon contractors use other methods that may also work in your home. The right system depends on the design of your home and other factors.

Sealing cracks and other openings in the floors and walls is a basic part of most approaches to radon reduction. Sealing does two things, it limits the flow of radon into your home and it reduces the loss of conditioned air, thereby making other radon reduction techniques more effective and cost-efficient. The EPA does not recommend the use of sealing alone to reduce radon because, by itself, sealing has not been shown to lower radon levels significantly or consistently. It is difficult to identify and permanently seal the places where radon is entering. Normal settling of your house opens new entry routes and reopens old ones.

Any information that you may have about the construction of your house could help your contractor choose the best system. Your contractor will perform a visual inspection of your house and design a system that is suitable. If this inspection fails to provide enough information, the contractor will need to perform diagnostic tests to help develop the best radon reduction system for your home. Whether diagnostic tests are needed is decided by details specific to your house, such as the foundation design, what kind of material is under your house, and by the contractor's experience with similar houses and similar radon test results.


How much does it cost to reduce radon in an existing home?

The cost of making repairs to reduce radon is influenced by the size and design of your home and other factors. Most homes can be fixed for about the same cost as other common home repairs, like painting or having a new hot water heater installed. The average cost for a contractor to lower radon levels in a home is about $1,200, although this can range from $800 to about $2,000. Your costs may vary depending on the size and design of your home and which radon reduction methods are needed.


Who should I hire to correct a radon problem?

Lowering high radon levels requires technical knowledge and special skills. You should use a contractor who is trained to fix radon problems.

The EPA stopped operating its National Radon Proficiency Program (RPP) on October 1, 1998. That program was designed to test radon contractors and provide a measure of quality control. Today two national organizations certify radon professionals. 

  1. National Radon Proficiency Program - Find nationally certified radon measurement and mitigation professionals in your area.

  2. National Radon Safety Board - Find nationally certified radon measurement and mitigation professionals in your area.


If you plan to fix the problem in your home yourself, we recommend you contact the Radon Fix-It line (1 (800) 644-6999) for more information on DIY mitigation. It is strongly recommended that a qualified professional design and install each system.  


Questions to ask your certified professional


Below are a number of topics that the NC Radon Program recommends addressing with whomever you hire to conduct your mitigation.

  1. Will the contractor provide references of past radon reduction work? Did you contact references?

  2. Can the contractor explain what the work will involve and how the radon reduction system will work?

  3. Did the contractor physically inspect your home’s structure before giving you an estimate?

  4. Did the contractor review your radon measurement results and determine if appropriate testing procedures were followed?


Do the contractors’ Proposals and Estimates include?

  1. Proof of current Certification for Radon Mitigation with either National Radon Proficiency Program (NRPP) or NRSB (National Radon Safety Board)?

  2. Proof of liability insurance and having all necessary licenses to satisfy local requirements?

  3. Does the contractor charge a fee for diagnostic tests? Many contractors give free estimates, but they may charge for diagnostic tests. These tests may help determine what type of radon reduction system should be used and in some cases diagnostics are helpful for initial design of a system.

  4. A guarantee to reduce radon levels to less than 4.0 pCi/L and if so, for how long?


Important information that should appear in the Contract includes:

  1. The total cost of the job, including all taxes and permit fees; how much, if any, is required for a deposit; and

  2. when payment is due in full.

  3. The time needed to complete the work.

  4. Agreement by the contractor to obtain necessary permits and follow required building and electrical codes.

  5. Note: Modification or addition of existing electrical wiring usually requires a licensed electrician.

  6. Statement that the contractor carries liability insurance and insured to protect you in case of injury to persons,

  7. or damage to property, while the work is being done.

  8. Guarantee the contractor will be responsible for damage during the job and cleanup after the job.

  9. Details of any guarantee to reduce radon below a negotiated level.

  10. Details of warranties associated with the hardware components of the mitigation system.

  11. Declaration stating whether any warranties or guarantees are transferable if you sell your home.

  12. Description of homeowner responsibilities to make work areas accessible prior to start.


Below is a list of basic installation requirements:


Radon reduction systems must be clearly labeled to avoid accidental changes to the system that could disrupt its function.

The exhaust pipes of soil suction systems must vent above the surface of the roof and 10 feet or more above the ground, and must be at least 10 feet away from windows, doors or other openings that could allow radon to reenter the home, if the exhaust pipes do not vent at least 2 feet above these openings.

The exhaust fan is properly located. For instance, it should be installed in unconditioned space and the exhaust side of the piping should not be routed through any conditioned space.

A warning device must be installed to alert you if an active system stops working properly. The warning device must be placed where it can be seen or heard easily.

Post-mitigation radon test should be done within 30 days of system installation, but no sooner than 24 hours after activation. Note: Closed-house conditions for at least 12 hours before test begins.


Will any more testing be needed after a radon mitigation system has been installed?

Most radon reduction systems include a monitor that will alert you if the system needs servicing. However, regardless of who fixes the problem, you should test your home afterward to be sure that radon levels have been reduced. This test should be conducted no sooner than 24 hours nor later than 30 days following completion and activation of the mitigation system(s). Potential conflict of interest can be avoided by using an independent tester.

In addition, it's a good idea to retest your home sometime in the future to be sure radon levels remain low. Testing should be done at least every two years or as required or recommended by state or local authority. Retesting is also recommended if the building undergoes significant alteration.


Are funds available to reduce high radon levels in rental housing?

There are some federal programs that might be used to help fund radon reduction in homes that are affordable to limited income families. These programs generally give money to local agencies or groups, which then fund the work. Some examples are:

  1. Community Development Block Grant (CDBG) program—funds rehabilitation and repair of affordable housing. For more information, call the U.S. Department of Housing and Urban Development (HUD) at (202) 708-3587.

  2. "203k" program—funds rehabilitation and repair of single family homes. For more information, call HUD at (202) 708-2121.

  3. Environmental Justice Grants—funds community-based organizations and tribal governments addressing environmental concerns of people of color and low income communities. For more information, call the EPA's Office of Environmental Justice at (800) 962-6215.



North Carolina Radiation Protection Section

5505 Creedmoor Rd, Suite 100, Raleigh, NC 27612

1645 MSC, Raleigh NC 27699-1645


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