Professional radon testing measures the radon concentration in your home's air over 48 to 96 hours using a continuous monitor or charcoal kit under closed-house conditions, with a written report of the result. In Plymouth County, a professional test runs $175 to $275, and it's the only way to know whether your home needs mitigation.
Two identical capes on the same Plymouth street can test at 1.5 and 11.0. Radon depends on the soil seams, foundation cracks, and pressure dynamics under one specific house: yours. That's why testing comes before every other decision, and why anyone quoting you a mitigation system without a number is selling, not solving.
Windows and doors stay closed (normal entry and exit is fine) for 12 hours before and during the test. This measures your home the way the EPA protocol requires, not the way a breezy weekend makes it look.
The monitor goes in the lowest lived-in level, positioned away from drafts, sumps, and exterior walls per protocol. Placement is half of accuracy.
Continuous monitors log hourly readings, which also flags tampering or unusual swings: this is why buyers' attorneys prefer them in transactions.
Your average concentration, the hourly graph where applicable, and a plain-English read of what the number means. Results within 48 hours of pickup.
The $30 hardware store charcoal kit is genuinely better than not testing. Its weaknesses are placement errors, closed-house discipline, and lab turnaround. Where it really doesn't belong is a real estate transaction, where protocol, chain of custody, and a defensible report decide whether the result stands. For a curiosity baseline, run the kit. For a decision, run the pro test.
A continuous monitor doesn't just give you an average. It gives you a shape, and the shape tells stories:
Steady line around one number: classic soil-gas entry, constant pressure, predictable. The average is trustworthy and the mitigation design is straightforward.
Big overnight peaks, daytime dips: the stack effect signature. The house pulls hardest when it's sealed and the temperature differential is largest. Your lowest bedroom sees the peak numbers, which matters more than the average if someone sleeps down there.
A cliff mid-test: somebody opened windows, ran a whole-house fan, or propped the bulkhead. In a personal test that's a do-over conversation. In a transaction test, the logged timestamp is exactly why attorneys prefer monitors: the data polices itself.
Weather swings: storms and pressure fronts move radon. A test spanning a nor'easter can read differently than a calm week, which is why the protocol wants 48 hours minimum: enough time for weather noise to average out.
This is also the honest answer to "my neighbor tested and they're fine." Different slab, different cracks, different soil seam under the footprint, different result. The only number that means anything is measured under your roof.
A low air test doesn't clear your well water: those are separate pathways with separate tests, and Carver-Plympton geology can produce a clean basement over hot water. A single low test doesn't clear the house forever: foundations crack, renovations change airflow, and retesting every few years costs less than one dinner out. And a moderate result (that 2.0 to 4.0 band) isn't a pass or a fail: it's a judgment call about who uses your lowest level and how many hours a day they're down there. A storage basement and a kid's bedroom are not the same 3.1.
Results within 48 hours of monitor pickup, in writing, with the graph where the device provides one, and a plain-English paragraph on what the number means for your specific situation. If the answer is "you don't need mitigation," that's the answer you get. A testing service that always finds a problem isn't a testing service; it's a sales funnel with a monitor.
$175 – $275
per test, written report included
Written report within 48 hours of the monitor coming out. Transaction tests get priority.
Levels usually run higher in winter when the house is sealed and the stack effect is strongest. Any season is valid under closed-house protocol; winter numbers are just your ceiling.
Yes, and slab homes in The Pinehills test high more often than owners expect. No basement doesn't mean no radon.
A separate test, worth adding if you're on a private well in Carver, Plympton, or South Plymouth. See radon in well water treatment
Radon Mitigation for Plymouth and Plymouth County. Test it. Fix it. Prove it's fixed.
(508) 503-6186