What Is a Radon Inspection and Should You Get One?
Radon is a naturally occurring gas that seeps up from the ground through cracks and gaps in a foundation, and because it has no smell, color, or taste, testing is the only way to know whether it’s present at a level worth addressing before moving in.
The short answer
A radon inspection places a testing device in the lowest livable level of a home for a set period, then measures the concentration of radon gas in the air. Results are compared against a threshold set by government health guidance, which can change over time, to determine whether the level is considered elevated. If a test comes back elevated, mitigation systems exist that are generally effective at reducing radon levels, though results and costs vary by property, foundation type, and local soil and geology.
How the test typically works
- Short-term tests. A device is placed in the lowest lived-in area of the home under closed-house conditions for a few days, offering a quicker but less representative snapshot of typical exposure.
- Long-term tests. A device left in place for a longer stretch offers a more representative picture of year-round exposure, though the timeline doesn’t always fit within a typical home purchase and the negotiation deadlines that come with it.
- Continuous monitors. Some inspectors use electronic devices that record hour-by-hour readings, which can help flag whether unusual conditions during the test period, such as a storm or an unusually sealed-up house, skewed the result.
- Either way, the test is arranged separately from the general walkthrough, sometimes by the same inspection company and sometimes by a dedicated radon specialist with calibrated equipment.
Why it’s worth considering beyond the general inspection
The general home inspection doesn’t test for radon as a standard part of its scope, since it requires a dedicated device and a set testing period rather than a visual walkthrough. In that sense it functions much like a mold inspection — a targeted add-on aimed at one specific, otherwise invisible concern rather than the home’s overall condition as a whole. Radon levels can also vary meaningfully between two similar homes on the same street, since local soil composition and foundation design play a large role.
If levels come back elevated
An elevated result doesn’t necessarily mean the property has to be ruled out. Mitigation systems, typically installed by a licensed contractor, work by venting gas from beneath the foundation before it enters the living space, and installation is often completed within a matter of days once scheduled. Depending on timing, the cost and responsibility for mitigation can become part of the negotiation formalized through a repair addendum.
Fitting it into the buying timeline
Because a short-term test is the more common choice during a purchase, it’s worth scheduling early in the inspection contingency period so there’s enough time to review results and negotiate before the deadline passes, particularly since weather and ventilation conditions can affect how quickly a valid reading is obtained.
The takeaway
Radon testing addresses a risk that’s invisible by nature, which is part of why it functions as a deliberate add-on rather than an assumption either way — a property’s history, region, foundation type, and construction all factor into whether ordering one makes sense.