Radon Test Before Listing Home For Sale

Before Listing Your Home for Sale, Take Care of the Small Stuff. And, Have a Radon Test

Q: This isn’t a question, but a comment/suggestion. I read one of your columns on your website talking about taking care of the small stuff when it comes time to list your home for sale.

You advise people to get a home inspection before they market their home. And, you suggested that they can make all the repairs to the home before they list it for sale. You also said that you can use the presale inspection as a marketing strategy.

I wanted to add to your suggestions. I would also advise having a long-term radon test (90 days to one year) done on a home before homeowners market the home for sale. This is much better than the short-term test after signing a contract. Long-term tests are more accurate and if you need to install a mitigation system, it allows the seller time to shop around.

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A: Thanks for your suggestion. Sounds like you’ve got some first-hand experience with radon causing problems for a home seller.

First, a refresher on radon. Radon is an odorless and colorless gas that can cause extremely serious health problems, including lung cancer. In fact, it is the leading cause of lung cancer in non-smokers. Children are at a much greater risk from radon because their lungs are smaller, they breathe faster and they have smaller, less developed organs overall, according to the North Carolina Department of Health and Human Services.

The gas comes into homes from underground and seeps in through cracks in the basement floors or where the walls and floors join. When radon does get it, the levels can increase until they become a health hazard. You can’t smell it or see it. That’s partly what makes it so dangerous. The United States Environmental Protection Agency (EPA) recommends that homeowners take action when the levels of radon are greater than 4 pCi/L (or 150 Bq/m3). These are the customary measures used to determine the level of radon: picocuries per liter or becquerel per cubic meter. It’s a way to measure the amount of radon in a volume of air.

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The EPA has a map that assigns three levels of radon to areas in the United States. Most of the midwest, upper midwest and northeast states tend to have higher levels of radon than the south or along the western coast.

Do you live in an area where there could be higher levels of radon? Test to see if your home’s levels are below the EPA recommended levels. Our reader recommends taking a longer term approach to reading radon levels. From our reading of various sources, and talking to various contractors through the years (and testing our own basement), radon levels can fluctuate greatly depending on the weather. And even by season. The levels may also be higher or lower in different years. A quick internet search will reveal there are many factors that could affect radon levels in homes. That’s why you want to test frequently.

Radon inspectors will typically place radon readers in basement levels and first floor levels of homes for around 48 hours or so before taking them down and evaluating the test. Homeowners will be asked to keep the areas being monitored to close air ducts, windows and doors. In essence, they want the monitored rooms to be sealed off to let the radon accumulate over the time of the test to get the level of radon in a closed environment.

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What our reader is saying is that a two day test may sample the home when radon levels are at their highest or lowest but may not provide an overall accurate reading for the home. In Sam’s deals, where radon levels are above 4.0 pCi/L, homeowners usually install a radon remediation system.

In the most basic sense, a radon remediation system is one that pulls air out from below the foundation of a home and draws that air to the exterior of the home. The reasoning is that the system will catch the radon gas before it infiltrates the home. These systems have a fan that continually pulls air out at all times. In homes with sump pumps, the system may cover the sump pump area and pull that air out. When a home has no sump pump, the radon company may drill a hole in the basement floor and use that hole to draw out air from underneath the home.

A long term test should provide additional information on the long-term levels of radon in a home as our reader suggests. But, it’s unclear what will satisfy a prospective buyer. You might put in one system and think it works perfectly well. But a buyer might hire a radon inspector who tests when the levels are high and you’ll be asked to install a different system.

Installing a radon mediation system 

If you test over time you discover that you have high radon levels, you might want to consider installing a radon remediation system. Even if you’re older and don’t have young children in the house. You can call various companies in your area and compare their products and installations. First, decide on a company and system that is right for you and your budget. That will allow you to install the mitigation system on your timetable rather than rushing to get it done once you have a contract to sell your home.

©2025 by Ilyce Glink and Samuel J. Tamkin. Distributed by Tribune Content Agency.

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