2026-05-06 · 5 min read
Radon Mitigation Cost in Illinois (2026)
Illinois averages 5.1 pCi/L with some of the highest-risk counties in the Midwest. Here's what mitigation costs in Chicago, Springfield, and downstate Illinois.
Illinois Radon at a Glance
Illinois averages 5.1 pCi/L statewide. The Illinois Emergency Management Agency (IEMA) Radon Section estimates approximately 40% of Illinois homes test above 4 pCi/L, with higher rates in the northwest.
Two geological zones create elevated risk: northwest Illinois over the Galena Dolomite and historic lead-zinc mining geology (Jo Daviess, Carroll, Whiteside counties run exceptionally high), and the glaciated central Illinois plains (McLean, Tazewell, Peoria counties).
Illinois Contractor Licensing
Illinois requires a state license for radon contractors through IEMA. This is one of the stronger state programs — it creates accountability and a publicly searchable contractor list.
Verify any Illinois contractor at iema.illinois.gov/radon or at radonproficiency.org. Unlicensed contractors cannot legally perform mitigation in Illinois.
What Mitigation Costs in Illinois
Slab or Basement: $850–$2,000
- Standard slab, downstate: $850–$1,400
- Finished basement, Chicago suburbs: $1,100–$1,900
- Chicago proper (older construction, complex routing): $1,200–$2,200
- Multiple zones: $1,500–$2,500
Crawl Space: $2,500–$6,000
Illinois has significant crawl space housing stock, particularly in older downstate communities:
- Basic crawl space: $2,500–$3,500
- With vapor barrier upgrade: $3,000–$5,000
- Large footprint or difficult access: $4,000–$6,000
Chicago vs. Downstate
Chicago metro contractors (DuPage, Kane, Lake, McHenry counties) charge $150–$400 more than comparable downstate contractors. The same job in Bloomington-Normal or Springfield typically runs $200–$500 less than in Naperville or Schaumburg.
Northwest Illinois: The Outlier
Jo Daviess County (Galena area) and Carroll County average some of the highest indoor radon in Illinois — regularly above 10 pCi/L. Homes in this region often require higher-suction fans and may need multiple suction points. Budget toward the higher end of ranges.
Illinois Resources
- IEMA Radon Section: iema.illinois.gov/radon or 800-325-1245
- Illinois certified contractor search: iema.illinois.gov
- Verify NRPP: radonproficiency.org
Frequently Asked Questions
How much does radon mitigation cost in Illinois?
Illinois homeowners typically pay $850–$2,000 for a standard slab or basement job. Chicago-area contractors charge slightly more; downstate is comparable to other Midwest markets. Crawl spaces run $2,500–$6,000.
Which Illinois counties have the highest radon?
The highest-testing counties include Jo Daviess, Carroll, Whiteside, and Bureau in northwest Illinois over the Galena Dolomite and lead-zinc mining district. Central Illinois counties (Peoria, Tazewell, McLean) also test well above average.
Does Illinois require a licensed radon contractor?
Illinois requires radon mitigators to be licensed through the Illinois Emergency Management Agency (IEMA) Radon Section. Both NRPP and NRSB certifications satisfy the state requirement. Verify any contractor at iema.illinois.gov.
Is Chicago radon a real concern?
Yes. Cook County averages approximately 4.5–5.0 pCi/L. Chicago-area homes with basements — particularly in the northern and western suburbs (DuPage, Kane, McHenry counties) — test above the action level at a significant rate. Chicago proper has lower rates due to slab construction and building density, but basements in older Chicago neighborhoods do test elevated.
Find a Certified Mitigator Near You
Every contractor on RadonBase is NRPP or NRSB certified — mitigators only, no testers.
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