My Radon Test Came Back High. What Should I Do Next?

Tue, 06 Oct 2026 20:00:05 GMT

Seeing an elevated number on a radon report can be unsettling, especially if you were not expecting a problem. The useful part is that a radon test gives you something concrete to act on. Radon cannot be seen or smelled, so testing is how homeowners learn whether the concentration inside a specific house needs attention.

If your radon result is 4 pCi/L or higher, the U.S. EPA recommends taking action to reduce the level. The next step is not to guess at a system or simply choose the largest fan. It is to understand the test, evaluate the home, and design a mitigation system around the way air moves beneath that particular foundation.

Start by Reviewing the Test Result

Before planning mitigation, look at the actual test report. Note the measured radon level, where the device was located, how long the test ran, and whether the test conditions were appropriate. A short-term test can be useful for making a timely decision, while a long-term test is more representative of a home’s year-round average because radon levels can vary from day to day and season to season.

If the result came from a real-estate inspection or a professional continuous monitor, keep the full report. If you used a home test kit, make sure you followed the manufacturer’s instructions for placement, test duration, closed-house conditions when required, and laboratory return.

The EPA recommends fixing a home when the radon level is 4 pCi/L or higher and notes that levels below 4 pCi/L still carry some risk. That means the decision should be based on the measured result and your goals, not on whether a neighbor needed a system.

A High Result Does Not Mean the Home Is “Bad”

Radon comes from the natural breakdown of uranium in soil and rock. Soil gas can enter through cracks, floor joints, sump openings, utility penetrations, crawl spaces, and other pathways. Elevated radon can occur in older homes, new homes, homes with full basements, and slab-on-grade construction.

It also does not mean the home cannot be fixed. Active radon mitigation systems are designed to create negative pressure beneath the foundation so radon-laden soil gas is collected before it enters the occupied space and is safely exhausted outdoors.

SharpShooter explains its residential approach in more detail on the single-family radon mitigation page .

The House Needs to Be Evaluated Before the System Is Designed

Two homes with the same test result may need different systems. Foundation construction is one reason. One house may have a drain-tile system that communicates well beneath the slab, while another may require one or more direct sub-slab suction points. Finished basements, additions, crawl spaces, sump pits, attached garages, and separate slab areas can all affect the design.

SharpShooter uses diagnostic testing to determine whether suction created in one location is reaching the areas that need to be controlled. That matters because installing a fan and PVC pipe does not by itself prove that negative pressure extends beneath the full foundation.

Drain-tile depressurization: may use an existing drainage system to create suction beneath the slab.
Sub-slab depressurization: uses suction points created through the slab where needed.
Multiple foundation zones: may require additional testing or suction points.
Crawl spaces: may need separate treatment depending on test results and communication with the rest of the home.

Do Not Choose the Fan Before You Understand the Pressure Field

A bigger radon fan is not automatically a better radon fan. An undersized fan may fail to create enough negative pressure, while an oversized fan can use more electricity and may pull more conditioned air from the home if air leaks are not controlled.

SharpShooter’s approach is to use diagnostic information to select a fan appropriate for the foundation and airflow requirements. The system should be treated as a complete design: suction points, sealing, pipe diameter and routing, fan selection, exhaust location, monitoring, and access for future service all work together.

Know What Will Be Sealed—and Why

Accessible openings that allow indoor air to be pulled into the soil-gas collection system can reduce efficiency. Sump covers, slab penetrations, and other openings may need sealing as part of the mitigation work.

Sealing alone is generally not the same as mitigation. The purpose of sealing is to support the pressure-control system and reduce unwanted air leakage. Your contractor should be able to explain what will be sealed and how necessary equipment, such as a sump pump, can still be serviced.

After Installation, Check the System and Retest

An active system should include a way for the homeowner to see whether the fan is creating suction. SharpShooter installs a U-tube manometer on its residential systems. Unequal fluid levels indicate that the system is creating pressure; a reading at zero can indicate that the fan is not operating and should be checked.

The manometer tells you about system operation, but it does not measure the radon concentration in the room. That is why post-mitigation radon testing matters. A follow-up test measures the result after the system is running.

Keep the original radon report, the mitigation documentation, system information, and the post-mitigation test together. Those records are useful for future testing, fan service, renovations, and eventual real-estate transactions.

When Should You Test Again?

Radon levels can change over time. The EPA recommends considering retesting if living patterns change and you begin using a lower level of the home, and notes that buyers may request a new test if an older test is no longer recent or if the home has been altered since the previous measurement.

Renovations that affect the foundation, basement use, drainage, or building pressure are good reasons to think about testing again. Periodic testing also provides reassurance that conditions have not materially changed.

Frequently Asked Questions

Is 4 pCi/L an emergency?

The EPA uses 4 pCi/L as its recommended action level for fixing a home. An elevated result deserves action, but it does not mean you need to make an uninformed decision immediately. Review the test and arrange a qualified mitigation evaluation.

Should I run another test before installing a system?

That depends on the type of test, the result, why the test was performed, and whether valid test conditions were maintained. In a time-sensitive real-estate transaction, EPA guidance includes short-term testing options. A qualified radon professional can help you interpret the existing report and determine the appropriate next step.

Will sealing cracks fix high radon by itself?

Sealing can be an important part of a mitigation system, but it is generally used to support active soil depressurization rather than as a stand-alone solution for an elevated radon result.

How do I know the mitigation system actually lowered radon?

Check the system monitor to confirm the fan is operating, then complete a post-mitigation radon test to measure the indoor radon concentration after installation.

Get a Property-Specific Radon Mitigation Plan

If your Northeast Ohio home tested high for radon, SharpShooter Radon Mitigation can evaluate the building, perform diagnostic testing, and design a system around the property rather than relying on a one-size-fits-all layout. Review the radon mitigation FAQs or learn more about SharpShooter’s Northeast Ohio service approach before requesting your estimate.

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