If Your Are SELLING a Home:
EPA recommends that you test your home before putting it on the market and, if necessary, lower your radon levels. Save the test results and all information you have about steps that were taken to fix any problems. This could be a positive selling point.


Radon and Real Estate

If you are buying a home or selling your home, have it tested for radon.

For a new home, ask if radon-resistant construction features were used and if the home has been tested.

Fix the home if the radon level is 4 picoCuries per liter (pCi/L) or higher.

Radon levels less than 4 pCi/L still pose a risk, and in many cases, may be reduced.

Take steps to prevent device interference when conducting a radon test.

If your home has already been tested for radon – If you are thinking of selling your home and you have already tested your home for radon, review our Radon Testing Checklist to make sure that the test was done correctly. If so, provide your test results to the buyer.

No matter what kind of test you took, a potential buyer may ask for a new test especially if:

  • The radon test was not performed correctly;

  • The last test is not recent, e.g., within two years;

  • You have renovated or altered your home since you tested; or

  • The buyer plans to live in a lower level of the house than was tested, such as a basement suitable for occupancy but not currently lived in.

A buyer may also ask for a new test if your state or local government requires disclosure of radon information to buyers.

If your home has not yet been tested for radon – Have a test taken as soon as possible. If you can, test your home before putting it on the market. You should test in the lowest level of the home which is suitable for occupancy. This means testing in the lowest level that you currently live in or a lower level not currently used, but which a buyer could use for living space without renovations.

The radon test result is important information about your home’s radon level. Some states require radon measurement testers to follow a specific testing protocol. If you do the test yourself, you should carefully follow the testing protocol for your area. If you hire a contractor to test your residence, protect yourself by hiring a qualified individual or company.

You can determine a service provider’s qualifications to perform radon measurements or to mitigate your home in several ways. Check with your state radon office. Many states require radon professionals to be licensed, certified, or registered. Most states can provide you with a list of knowledgeable radon service providers doing business in the state. In states that don’t regulate radon services, ask the contractor if they hold a professional proficiency or certification credential. Such programs usually provide members with a photo-ID card, which indicates their qualification(s) and its expiration date. If in doubt, you should check with their credentialing organization. Alternatively, ask the contractor if they’ve successfully completed formal training appropriate for testing or mitigation, e.g., a course in radon measurement or radon mitigation.

If You Are BUYING a Home:
If the home has already been tested for radon
– If you are thinking of buying a home, you may decide to accept an earlier test result from the seller, or ask the seller for a new test to be conducted by a qualified radon tester. Before you accept the seller’s test, you should determine:

  • The results of previous testing;

  • Who conducted the previous test: the homeowner, a radon professional, or some other person;

  • Where in the home the previous test was taken, especially if you may plan to live in a lower level of the home. For example, the test may have been taken on the first floor. However, if you want to use the basement as living space, test there; and

  • What, if any, structural changes, alterations, or changes in the heating, ventilation, and air conditioning (HVAC) system have been made to the house since the test was done. Such changes may affect radon levels.

If you accept the seller’s test, make sure that the test followed the Radon Testing Checklist.

If you decide that a new test is needed, discuss it with the seller as soon as possible. If you decide to use a qualified radon tester, contact your state radon office to obtain a copy of their approved list of radon testing companies.

If the home has not yet been tested for radon – Make sure that a radon test is done as soon as possible. Consider including provisions in the contract specifying:

  • Where the test will be located;

  • Who should conduct the test;

  • What type of test to do;

  • When to do the test;

  • How the seller and the buyer will share the test results and test costs (if necessary); and

  • When radon mitigation measures will be taken and who will pay for them.

Make sure that the test is done in the lowest level of the home suitable for occupancy. This means the lowest level that you are going to use as living space which is finished or does not require renovations prior to use. A state or local radon official or qualified radon tester can help you make some of these decisions.

If you decide to finish or renovate an unfinished area of the home in the future, a radon test should be taken before starting the project and after the project is finished. Generally, it is less expensive to install a radon-reduction system before (or during) renovations rather than afterwards.

EPA recommends that you know what the indoor radon level is in any home you consider buying. Ask the seller for their radon test results. If the home has a radon-reduction system, ask the seller for information they have about the system.

If the home has not yet been tested, you should have the housed tested. If you are having a new home built, there are features that can be incorporated into your home during construction to reduce radon levels.

Why should I buy a radon-resistant home? – Radon-resistant techniques work. When installed properly and completely, these simple and inexpensive passive techniques can help to reduce radon levels. In addition, installing them at the time of construction makes it easier to reduce radon levels further if the passive techniques don’t reduce radon levels below 4 pCi/L. Radon-resistant techniques may also help to lower moisture levels and those of other soil-gases. Radon-resistant techniques:

  1. Making Upgrading Easy: Even if built to be radon-resistant, every new home should be tested for radon after occupancy. If you have a test result of 4 pCi/L or more, a vent fan can easily be added to the passive system to make it an active system and further reduce radon levels.

  2. Are Cost-Effective: Building radon-resistant features into the house during construction is easier and cheaper than fixing a radon problem from scratch later. Let your builder know that radon-resistant features are easy to install using common building materials.

  3. Save Money: When installed properly and completely, radon-resistant techniques can also make your home more energy efficient and help you save on your energy costs.

In a new home, the cost to install passive radon-resistant features during construction is usually between $350 and $500. In some areas, the cost may be as low as $100. A qualified mitigator will charge about $300 to add a vent fan to a passive system, making it an active system and further reducing radon levels. In an existing home, it usually costs between $800 and $2,500 to install a radon mitigation system.

What Are Radon-Resistant Features? – Radon-resistant techniques (features) may vary for different foundations and site requirements. If you’re having a house built, you can learn about EPA’s Model Standards (and architectural drawings) and explain the techniques to your builder. If your new house was built (or will be built) to be radon-resistant, it will include these basic elements:

  1. Gas-Permeable Layer: This layer is placed beneath the slab or flooring system to allow the soil gas to move freely underneath the house. In many cases, the material used is a 4-inch layer of clean gravel. This gas-permeable layer is used only in homes with basement and slab-on-grade foundations; it is not used in homes with crawlspace foundations.

  2. Plastic Sheeting: Plastic sheeting is placed on top of the gas-permeable layer and under the slab to help prevent the soil gas from entering the home. In crawl spaces, the sheeting (with seams sealed) is placed directly over the crawlspace floor.

  3. Sealing and Caulking: All below-grade openings in the foundation and walls are sealed to reduce soil gas entry into the home.

  4. Vent Pipe: A 3- or 4-inch PVC pipe (or other gas-tight pipe) runs from the gas-permeable layer through the house to the roof, to safely vent radon and other soil gases to the outside.

  5. Junction Boxes: An electrical junction box is included in the attic to make the wiring and installation of a vent fan easier. For example, you decide to activate the passive system because your test result showed an elevated radon level (4 pCi/L or more). A separate junction box is placed in the living space to power the vent fan alarm. An alarm is installed along with the vent fan to indicate when the vent fan is not operating properly.

Credit: U.S. Environmental Protection Agency