How to Lower Radon Levels in Your House
The most reliable way to lower radon is to hire a certified professional to install an active soil depressurization system, which draws radon from beneath the house and vents it outdoors. Before choosing a solution, confirm the radon level with a proper test; sealing cracks alone rarely provides enough protection.
Start With an Accurate Radon Test
Radon is an invisible, odorless radioactive gas that can enter through foundation cracks, floor joints, sump pits, crawl spaces, and gaps around pipes. Because levels vary from home to home, testing is the only way to know whether you have a problem.
For an initial screening, place a short-term test in the lowest level that could be regularly occupied. Keep it away from kitchens, bathrooms, exterior walls, drafts, direct sunlight, and high humidity. Follow the test instructions closely, including any closed-house conditions required before and during testing.
If the result is 4 picocuries per liter (pCi/L) or higher, the EPA recommends taking action. Consider mitigation for results between 2 and 4 pCi/L as well, since no radon level is completely risk-free.
Before making a major decision:
- Confirm a high short-term result with another short-term test or a long-term test.
- Use a certified measurement professional when the result affects a home sale.
- Avoid placing the device in an unfinished area that would never be occupied if a finished basement or first floor is the relevant living space.
- Check whether your state requires radon testers or mitigators to hold a state license.
A short-term test typically runs for 2 to 7 days. Long-term tests measure for more than 90 days and provide a better picture of the home’s year-round average.
Choose the Right Radon Mitigation System
Active soil depressurization is the standard solution for many homes. A contractor creates one or more suction points through the slab or foundation, connects them to PVC piping, and uses an in-line fan to pull radon-containing soil gas from beneath the house. The gas is then discharged safely above the roof or at another code-compliant location.
The design depends on the foundation:
- Basement or slab-on-grade: A sub-slab depressurization system draws air from beneath the concrete.
- Crawl space: A sealed plastic membrane covers the exposed soil, with suction applied beneath it.
- Drain tile or sump system: Existing drainage components may provide an effective suction route, but the sump usually needs an airtight, serviceable cover.
- Mixed foundation: The contractor may need multiple suction points or separate treatment zones.
Some homes can use passive systems, especially when radon piping was installed during construction. However, adding a fan often produces a larger and more dependable reduction.
Understand Typical Radon Mitigation Costs
A professionally installed system typically costs about $1,000 to $2,500 in many areas. Straightforward single-foundation homes may cost less, while large houses, finished basements, difficult routing, or multiple foundation types may push the price to $3,000 or more.
Possible expenses include:
- Initial professional testing: often $100 to $250
- Additional suction points or crawl-space membrane work
- Electrical installation for the fan
- Decorative or concealed pipe routing
- Permit or inspection fees where required
- Fan replacement, commonly needed after several years
- Electricity to run the fan continuously
Ask for a written proposal that identifies the system type, pipe route, fan location, discharge point, warranty, expected completion time, and post-installation testing. Most standard installations take less than a day, although complex homes may require one or two days.
Seal Openings, but Do Not Rely on Sealing Alone
Sealing foundation openings can improve a mitigation system’s performance and reduce conditioned-air loss. Useful areas to address include visible slab cracks, gaps around utility penetrations, open sump pits, floor-wall joints, and crawl-space membrane seams.
Sealing by itself is not usually a dependable radon remedy. Radon can move through tiny openings that are difficult to find, and pressure differences may continue pulling soil gas indoors. Treat sealing as part of a complete system, not as a substitute for active mitigation.
Opening windows can temporarily dilute indoor radon, but levels may rise again after the windows close. It also wastes heating or cooling energy and does not provide consistent protection.
Hire a Qualified Radon Contractor
Look for a professional certified by the National Radon Proficiency Program or the National Radon Safety Board, along with any license required by your state. Get two or three written estimates when time permits.
A strong proposal should include:
- Diagnostic testing or an explanation of the planned suction-point placement
- A continuously operating fan located outside the living space
- A visible system monitor showing whether suction is present
- Properly sealed pipe connections and foundation openings
- A discharge point positioned to prevent radon from reentering the home
- Clear warranties for workmanship and equipment
- An independent post-mitigation radon test
Red flags include promises that sealing alone will solve every problem, a fan installed in a basement or other occupied space, discharge beside a window, no system-pressure indicator, or refusal to provide certification and insurance information. Be cautious of guaranteed final readings before the home has been evaluated.
Find a certified radon professional near you
Retest and Maintain the System
Conduct a post-mitigation test no sooner than 24 hours after the system begins operating and generally within 30 days. Follow the testing instructions and keep the system running normally throughout the measurement period.
Check the system monitor periodically. It does not measure radon; it indicates whether the fan is creating suction. If its reading changes noticeably, contact the installer. Do not unplug the fan, because mitigation systems are intended to operate continuously.
Retest the home at least every two years and after major foundation work, HVAC changes, remodeling, or alterations to the mitigation system. Test again when buying or selling, even if a system is already installed.
Frequently Asked Questions
Can I lower radon by opening the windows?
Opening windows may reduce the reading temporarily, but it is not a permanent solution. Levels can quickly rise when the house is closed again.
How quickly does a mitigation system reduce radon?
An active system starts working as soon as the fan is operating. Allow at least 24 hours before beginning the post-installation test, then confirm performance with a properly placed test.
Can a radon level be reduced below 4 pCi/L?
In many homes, yes. A well-designed system can often reduce levels substantially, although the result depends on the foundation, soil, and system design.
Does a radon system hurt a home sale?
Usually, a properly installed system is reassuring because it shows the issue has been addressed. Keep the installation documents, warranty, and recent test results for buyers.