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How to Fix a Radon Problem/Radon Mitigation

When to Take Action

To help you protect your health and the health of your family, you should take action to fix your home if the result of one long-term test or the average of two short-term tests are 4 pCi/l or higher, and not on a single short-term screening test only. The higher the radon level in your home, the faster you should take action to reduce your exposure. The EPA and the Nevada Division of Public and Behavioral Health believe that you should try to reduce your radon levels as much as possible. Most homes can be reduced to 4.0 pCi/l or lower.

If your home has a radon problem, it can be fixed by installing a radon mitigation system in the home. EPA and the Nevada Division of Public and Behavioral Health recommends that you get a certified or licensed radon mitigation contractor to install the system.

Certified Radon Contractors

A radon mitigation contractor is a professional who can fix your home to reduce the radon level. Lowering high radon levels requires technical knowledge and special skills. The EPA and Nevada Division of Public and Behavioral Health recommend the use of individuals who have been trained, passed an examination and are certified to provide radon mitigation services. To assist Nevada citizens, the Nevada Radon Education Program has compiled a list of Certified Mitigation Professionals in Nevada.

Radon professionals are certified through one of the two national voluntary radon proficiency programs — the National Radon Proficiency Program (NRPP) and the National Radon Safety Board (NRSB). Both organizations list certified radon professionals on their websites:

You can also contact Nevada Division of Public and Behavioral Health, Radiation Control Program at 775-687-7550 for more information on hiring radon professionals.

Certified radon professionals will review testing guidelines and measurement results to determine the necessity for mitigation. He or she will evaluate the radon situation; provide a written and detailed proposal for mitigation; design the radon mitigation system; install the system according to EPA Standards; and verify that the completed system is functioning and effective.

You should ask to see a photo identification card of your radon professional. The radon professional's identification number should be noted in the test report and other documents.

Fixing It Yourself

Cover of Protecting Your Home From Radon Book

What Else You Can Do To Lower Risk

If you have to wait a while before you can reduce your radon problem, the EPA recommends these immediate steps to reduce risk:

  • Stop smoking and discourage smoking in your home. This reduces an overall risk of lung cancer.
  • Spend less time in areas where radon may be concentrated, such as the basement (lowest living area of the home).
  • Open windows and turn on fans to increase air flow. Good ventilation helps radon disperse naturally.
  • If your home has a crawl space, make sure the vents are fully open all year long. However, in some climates, this may result in an energy loss or frozen pipes.
  • Remember: These steps are not a substitute for mitigation. If your home needs mitigation, these steps will help until you can have it done.

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.

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 crawl space (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 crawl space 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. EPA generally recommends methods that prevent the entry of radon.

In many cases, simple systems using underground pipes and a radon system fan may be used to reduce radon. Such systems are called active soil depressurization, and do not require major changes to your home. These systems remove radon gas from below the concrete floor, or a membrane in a crawl space, and the foundation before it can enter the home. 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.

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.

Sub slab suction photo

Sub-slab depressurization is the
most common and usually the most
reliable radon mitigation method.

In houses that have a basement or a slab-on-grade foundation, radon is usually reduced by one of four types of active soil depressurization: sub-slab depressurization, drain tile depressurization, sump hole depressurization, or block wall depressurization. Sub-slab depressurization is the most common and usually the best method for reducing radon. In this system, one or more suction pipes pass through the slab into the crushed rock or soil underneath. The pipes also may be put below the concrete slab from outside the house. A radon vent fan connected to the suction pipe draws the radon gas from below the house and releases it into the outdoor air. See the diagram for an example of a sub-slab depressurization system.

If your home has a crawlspace, the mitigation method will depend on the type of floor, how accessible it is, and whether the space is large enough to work in. If the crawlspace has a concrete floor, the preferred mitigation technique is sub-slab suction. If it has an earth floor, the preferred mitigation technique is sub-membrane suction. With sub-membrane depressurization, the floor is covered with a thick plastic sheet sealed to the crawlspace walls, foundation piers and any penetrations of the membrane. A radon system fan and piping system then draws the radon from under the membrane and vents it outdoors.

Homes with water control systems such as sump pumps, French drains, or an exterior loop of buried water-collection pipe can be effectively mitigated by connecting the active soil depressurization system to the existing water control system.

As part of installing a mitigation system, cracks and other openings in walls and floors in contact with the ground are sealed. 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. 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. Sealing cracks helps limit the flow of radon into a home, reduce the loss of heated or cooled/conditioned air, and make radon mitigation systems work better and cost less to operate over time. However, 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.

Radon fans must be located in an unoccupied attic, a garage, or outside. The fan discharge is then routed up through the roof, or up along an outside wall, to a high point on the house. Although they must operate continually, operating costs of the fans are negligible due to their low power consumption (60 watts - less than most light bulbs - per fan).

A system indicator must be installed to warn the homeowner of any malfunctions.

Homes should be re-tested, but no sooner than 24 hours after a mitigation system has been operational.

The Benefits and Costs of a Radon Mitigation System

Radon reduction systems work. In most homes, use of radon-reducing features will keep radon levels to below 2 pCi/l. An effective radon mitigation system can reduce the radon level in your home by up to 99 percent.

Homeowners with radon systems have also experienced a reduction of other indoor air quality issues such as moisture and soil gas intrusion problems in their home. In an effort to produce scientific evidence of these observations, EPA has funded several radon system and moisture studies and research is still in the preliminary stages.

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 certified or licensed mitigation contractor to lower radon levels in a slab or basement home is about $2,500, and a crawl space home is about $3,800 or more. Your costs may vary depending on the size and design of your home, which radon reduction methods are needed, and the distance to travel to the mitigation location.

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.

Radon mitigation systems need occasional maintenance. Check your warning device (all properly installed systems should have one) frequently to make sure the system is working correctly. Radon system fans may last for five years or more (manufacturer warranties usually do not exceed five years). You may need to repair or replace older fans.

How To Know If a Radon Mitigation Contractor Did a Good Job

A radon mitigation contractor should perform the following basic steps when putting a radon mitigation system in your home:

  • Perform an evaluation of the home, including a visual inspection and other investigation and diagnostic techniques, when designing an appropriate system.
  • Label the radon mitigation system clearly to avoid accidental changes to the system. For example, the radon system pipe can be mistaken for a plumbing pipe.
  • To prevent radon from reentering the home, the mitigator should locate the discharge:
    • above the eave of the roof
    • at least 10 feet or more above ground level
    • be 10 feet or more away from any opening into an adjacent building
    • If any opening into the structure (window, door or other opening into conditioned spaces of the structure) is less than two feet below the discharge vertically, then the discharge must be at least 10 feet from the opening diagonally.

      The total required distance (10 feet) from the point of discharge to openings in the structure may be measured either directly between the two points or be the sum of measurements made around intervening obstacles.

      Whenever possible, the exhaust point should be positioned above the highest eave of the building and as close to the roof ridge line as possible.
  • Install a radon system fan in an appropriate place. The radon system fan must not be in or below a livable area. If installing a radon system fan outside, the fan must meet local electric code requirements for exterior use.
  • Follow local code requirements when installing electrical connections for radon mitigation systems.
  • Install a warning device that is easily seen or heard to alert you if your system stops working properly.
  • Explain and demonstrate how your radon mitigation system works and how to maintain it.
  • Provide you with written operation and maintenance instructions and copies of any warranties.

Once your contractor has completed these steps, you should verify the system is working by conducting a post-mitigation test within 30 days of installation but no sooner than 24 hours after your system is in operation with the fan on. Retest again at least every two years. In Nevada, it is recommended that testing be done during the heating season months.

For More Information
  • EPA Consumer's Guide to Radon Reduction
  • Information on radon mitigation training courses and copies of EPA's technical guidance documents are available from the Nevada Division of Public and Behavioral Health, Radiological Health Section at 775-687-7550.
  • Information and EPA publications are also available at the Nevada Radon Education Program offices, or call 1-888-RADON10 (888-723-6610).