Question 1

How much does radon mitigation cost in 2026?

Accepted Answer

A standard sub-slab depressurization system in a full-basement home runs $1,500-$2,500 typical, with a wider range of $800-$4,500 depending on foundation type, home size, and current radon levels. Crawl-space (sub-membrane) systems add 25%; block-wall systems add 80%. Heat-recovery ventilator (HRV) systems run $2,500-$6,500.

Question 2

What is the EPA action level?

Accepted Answer

4 pCi/L. The EPA recommends mitigation for any home testing at or above 4 pCi/L. Below 4 pCi/L, mitigation is voluntary; the EPA suggests considering action between 2-4 pCi/L. The average US home tests at 1.3 pCi/L.

Question 3

NRPP vs NRSB certification — which should I look for?

Accepted Answer

Both NRPP (National Radon Proficiency Program, AARST-administered) and NRSB (National Radon Safety Board) are recognized by federal and most state programs. Some states accept both; some require state-specific licensing on top. We list contractors by their primary cert body — either is fine to hire from. Verify the cert ID on the public registry before signing.

Question 4

Why is radon a real-estate issue?

Accepted Answer

Several states (PA, IL, NJ, MA, RI, FL among others) require radon disclosure on residential real-estate transfers. Lenders may also require testing on FHA/VA loans in high-radon counties. Test results above 4 pCi/L typically trigger a mitigation contingency in the contract — the seller installs a system, or buyer negotiates a credit.

Question 5

How long does mitigation take?

Accepted Answer

Sub-slab system: 4-6 hours in a single visit. Sub-membrane (crawl space): 6-8 hours, sometimes 2 visits. Block-wall: 1-2 days. HRV system: 1 day plus electrical. Re-test 30 days after install to confirm levels are below 4 pCi/L.

Question 6

Will mitigation completely eliminate radon?

Accepted Answer

A properly-installed system typically reduces radon by 50-99%, usually to well below 4 pCi/L. Some homes with very high initial levels (40+ pCi/L) may need a 2-pipe enhanced system or a second mitigation pass. Post-mitigation re-testing is industry standard and we recommend it as a $150-300 line item.

Question 7

Should I test before mitigation?

Accepted Answer

Yes. Without a current reading, you don't know what you're treating or how to size the system. A short-term test kit ($15-50, 2-7 days) gives a quick number; a long-term test (90+ days) gives the most accurate annual-average reading. Continuous radon monitors ($150-300, reusable) are increasingly popular for ongoing surveillance.

Question 8

What's the warranty?

Accepted Answer

Industry-standard: 5-year workmanship warranty on the installed system, 1-2 year warranty on the fan motor (consumable part, ~$300-500 to replace). A guarantee that post-mitigation radon levels stay below 4 pCi/L for at least 1 year is reasonable to expect from NRPP/NRSB-certified contractors.

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