Should I buy a house with high radon levels?
Yes, if the fix is in your repair request. At 4 pCi/L or higher, get a mitigator's bid and ask the seller to install a system or credit you.
Updated · By 
Ben Sikes
Should you buy a house with high radon levels?
Yes, if the fix is priced and in your repair request. The Environmental Protection Agency (EPA) says to fix the home if the radon level is 4 picocuries per liter (pCi/L) or higher, and that even very high levels can be reduced. The fix is a vent pipe and fan, and EPA says most homes can be fixed for about the same cost as other common home repairs. Get a certified mitigator's bid, then ask the seller to install the system or credit you for it before your deadline.
Key takeaways
- A 3.5 or 3.9 is worth a mitigator's bid too, since EPA's consider-fixing band starts at 2.
- For a typical single-family home, a qualified contractor can install the system in one day.
- If the seller installs it, ask for a follow-up test result taken 24 hours to 30 days after installation.
What radon level counts as high?
Anything at EPA's 4 pCi/L line or above counts as high. Below it, EPA still says "consider fixing when the radon level is between 2 and 4 pCi/L." So 3.5 or 3.9 is under EPA's line, but EPA also says "no level of radon is safe."
If your number came from a short-term test, know its limits. Radon levels vary from day to day and season to season, so EPA says a short-term test is less likely than a long-term test to show your year-round average. It can still be used to decide whether to fix the home when you need results quickly. The closer the result sits to the line, the less certain it is which side your year-round average falls on. Bob Vila adds that winter levels are usually higher, when homes are sealed tight against the cold.
Are high radon levels dangerous?
EPA treats high radon levels as a real lung cancer risk. Its radon health page says "radon is the second leading cause of lung cancer" and is "responsible for about 21,000 lung cancer deaths every year." About 2,900 of those deaths are among people who have never smoked. Some scientists dispute the precise count, but EPA says all the major health organizations agree with estimates that radon causes thousands of preventable lung cancer deaths every year.
The risk comes from long exposure. EPA's RadTown page puts it this way: "With prolonged exposure, radon may pose a health hazard." EPA's buyer guide says your chances of lung cancer from radon depend mostly on the home's radon level, the time you spend in it, and whether you smoke. Lowering the level lowers your risk, which is why the fix belongs in your request now, not on a someday list.
How do you fix high radon levels?
A certified radon mitigation contractor installs a system that pulls soil gas from under the floor and vents it outside. EPA's guide calls these "sub-slab depressurization" systems and says they "do not require major changes to your home." Crawl-space homes get a similar system under a plastic sheet. For a typical single-family home, National Radon Program Services says a qualified contractor can do the job in one day.
Sealing cracks alone is not the fix. EPA says sealing "has not been shown to lower radon levels significantly or consistently."
To find a mitigator:
- Call your state radon office. EPA's guide says many states require radon professionals to be licensed, certified or registered.
- Wisconsin's health department points you to the two national certification programs, the National Radon Proficiency Program and the National Radon Safety Board.
- Ask each one for a written bid. How to get repair estimates during the inspection period covers getting bids back inside your window.
What does radon mitigation cost?
Every radon mitigation price below covers the same job: a professionally installed system. The two state figures are local to those states.
| Source | Area | Installed system |
|---|---|---|
| National Radon Program Services (Kansas State University, with EPA) | National | $800 to $1,500 common, $1,200 average |
| Bob Vila | National | $771 to $1,185, about $978 average |
| Wisconsin Department of Health Services | Wisconsin | $1,000 to $2,000 average |
| Minnesota Department of Health | Minnesota | $1,500 to $3,000 |
Minnesota says the price depends on the type of system and how the home was built. Bob Vila says larger homes or complicated layouts can cost a few thousand dollars.
A worked example: you are in Wisconsin with no bid yet. The top of the state's average range is $2,000, and Bob Vila says a professional radon test typically costs less than $200. Use $2,200 for the system and a follow-up test as a placeholder, then swap in the mitigator's written bid.
If your report has other findings, Kept prices every line of an inspection report for $79, usually under 4 hours, and marks the ones that need a professional quote.
What should you ask the seller for?
Ask the seller for one of two things, in writing:
- The seller installs the system through a certified mitigator before closing, and gives you a follow-up test. National Radon Program Services says homes should be retested "no sooner than 24 hours (nor later than 30 days) after installation."
- A credit for the bid amount, so you hire the mitigator yourself after closing.
EPA's guide suggests the contract say when radon mitigation will happen and who will pay for it. Put the scope, the contractor type and the bid total on one line. If the seller installs, ask for the system's instruction manual and warranties too; National Radon Program Services says installers should hand both to the homeowner.
If the report shows a system already in place, EPA says to ask the seller for any information they have about it. Its testing checklist also says to make sure the vent fan is operating properly before the test. National Radon Program Services puts fan life spans at 10 to 15 years and says a home with a system should be retested every two years. What to ask for after a home inspection shows where it sits in your list, and the buyer repair request letter template has the wording.
What if the seller says no?
If the seller says no, you still have choices. Ask for a price reduction instead of the credit. Or take the house as is and pay for the system yourself once you own it.
Don't plan to do it yourself. Wisconsin says sub-slab depressurization "is not a do-it-yourself project unless you have considerable contractor skills."
If the seller refuses and the bid is more than you can absorb, your inspection contingency may let you cancel. When to walk away after a home inspection walks through that call. Your contract sets the exact dates and terms, so confirm with your agent or attorney.
How common is high radon in homes?
High radon is common enough that EPA says to know the radon level of any home you consider buying. It says "nearly one in 15 homes in the United States has a radon level that should be reduced."
Is a high radon level a deal breaker?
In EPA's view, a high radon level is a fixable finding: it calls "homes with radon problems cannot be fixed" a myth. What decides it is the bid next to the rest of your repair list and your cash.
If radon is one line on a longer report, upload your inspection report to Kept and get figures for the rest of your list while you wait on the mitigator's bid.
Sources
- EPA, Home Buyer's and Seller's Guide to Radon
- EPA, Health Risk of Radon
- EPA RadTown, Radon in Homes, Schools and Buildings
- National Radon Program Services, Reducing Radon in Your Home
- Wisconsin Department of Health Services, Radon Mitigation
- Minnesota Department of Health, Radon Mitigation Systems
- Bob Vila, Radon in Homes: What Home Buyers and Sellers Need to Know
Cost figures are modeled from public wage and materials data unless a line says observed. Kept is accountable for the numbers on this page, and corrections go to support@usekept.com. How we price.