Last updated 2026-07-17
A radon system on a house you’re buying is usually good news: someone already found the problem and paid to fix it. But “has a system” and “has a working, verified system” are different claims. Here’s how to tell them apart before you close — and what New Jersey law entitles you to along the way.
New Jersey’s radon statute (N.J.S.A. 26:2D-73) is short but useful: if the building has been tested for radon, the seller must give the buyer a copy of the results and evidence of any subsequent mitigation or treatment at the time the contract of sale is entered into. A house with a mitigation system has, by definition, been tested — so the paperwork obligation applies. If the seller can’t produce results, treat the system as unverified and test during your inspection window like any other house (how radon works in NJ sales).
Almost every NJ residential system is active sub-slab depressurization: a sealed suction point through the basement slab, PVC pipe running up through the house or along an exterior wall, an inline fan, and a discharge above the roofline. On a walk-through, check:
Remember what the manometer doesn’t tell you: it proves the fan runs, not that radon is low. Only a test proves levels.
| Item | What you want | Red flag |
|---|---|---|
| Statutory disclosure | Test results + mitigation evidence at contract (N.J.S.A. 26:2D-73) | Seller “can’t find” any records |
| Installer | NJDEP-certified mitigation business (verify at njradon.org / 800-648-0394) | Handyman install, no certification |
| Post-mitigation test | Passing result (below 4 pCi/L) after install | System never verified by a test |
| Most recent test | Within the last 2 years (EPA retest interval) | Last test is 8 years old |
| Manometer | Uneven fluid columns | Level columns; fan unplugged |
| Fan age | Known install date; under ~10 years | Original fan on a 15-year-old system |
| Warranty | Written, and confirmed transferable to you | Verbal assurances only |
EPA’s guidance for buyers of mitigated homes is specific — ask for a new test if:
In practice, most NJ buyers simply add radon to the home inspection (~$100–$300 — testing costs here) regardless, because the seller controls the house during your window and a fresh certified result resets the clock. A well-functioning system typically holds a home below 4 pCi/L and often below 2. If your test comes back at 4+ with the system running, the system needs diagnosis — an additional suction point, sealing work, or a stronger fan — which is a negotiation item exactly like an elevated test on an unmitigated house (mitigation pricing).
The fan is the system’s only moving part and its only real wear item. Industry cost data puts typical fan life at about 10 years (10–15 is the commonly quoted range), with replacement at $150–$300 parts and labor. Manufacturer warranties are shorter — EPA notes they tend not to exceed five years — and installer workmanship warranties vary widely in length and transferability. Ask the seller for the warranty in writing and ask the installing company whether it transfers to a new owner; many NJ installers will honor a transfer, but get it confirmed rather than assumed. Electricity to run the fan is modest: roughly $30–$75 a year.
Three habits keep a mitigated house mitigated: glance at the manometer every month or two (and after storms or electrical work), retest at least every two years with a ~$20 kit or free county kit, and retest after any renovation that touches the foundation or airflow. If the manometer ever levels out, call an NJDEP-certified mitigation business — it’s usually just a fan swap.
Generally the opposite. Elevated radon is common across northern and western NJ, and a documented system with a passing test is a solved problem — arguably better than an untested house next door. The system only becomes a concern if it comes with no paperwork, no recent test, or a manometer showing the fan isn't running.
New Jersey law (N.J.S.A. 26:2D-73) requires a seller whose building has been tested for radon to provide the test results and evidence of any mitigation at the time the contract of sale is entered into. Beyond that statutory minimum, ask for the installer's name and NJDEP certification, the post-mitigation test result, the most recent retest, and any transferable warranty.
Yes, in most cases. EPA's home buyer guidance says to ask for another test if more than two years have passed since the last one, if the home has been renovated since, or if you plan to live in a lower level than was tested. A working fan proves suction, not low radon — only a test proves levels, and mitigated homes should be retested at least every two years anyway.
Industry data puts typical fan life around 10 years (commonly quoted as 10–15), with replacement running about $150–$300 including labor. Manufacturer warranties are much shorter — EPA notes they tend not to exceed five years — so on an older system, budget for a fan as a routine wear item, like a water heater on a smaller scale.
It's a simple pressure gauge on the system pipe. Unequal fluid columns mean the fan is pulling suction under the slab — the system is on and working mechanically. Equal (level) columns mean no suction: the fan is off, unplugged, or dead. It does not measure radon; a manometer can read perfectly on a system that's poorly designed, which is why the recent test result matters more.
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