Illinois Radon Mitigation Cost by County, Foundation, and Rules
Compare typical local price ranges for basement, slab, and crawl space systems. Use the state-level ranges first, then open your county when you need a local estimate after a confirmed radon result.
Fastest Start
Use ZIP Instead of Scrolling
If you know the property ZIP, jump straight to the right county estimate instead of browsing the full state list.
Cost Basics
Foundation & Result Ranges
Use the national cost guide if you need basement, slab, crawl-space, or 4.0+ result context first.
Validate the Risk
Check IL Radon Levels
If you do not have a confirmed radon result yet, review EPA zone context before you compare mitigation pricing.
Browse Counties
Jump to County Pricing
Open your county if you already know the area and just need a local basement, slab, or crawl-space price range.
Official State Resource
Illinois radon program and rules
Use the state program link to verify local radon guidance, disclosure language, and contractor credential expectations before you act on an estimate.
Disclosure rule tracked
Illinois requires sellers to disclose known radon test results to buyers under the Residential Real Property Disclosure Act.
State licensing required
Illinois requires radon mitigation professionals to be licensed by the Illinois Emergency Management Agency (IEMA).
IL Cost Starting Point
Illinois cost range by foundation
Basement
$1040-$1868
Use this when the home has a basement or lowest-level slab that supports a standard sub-slab suction system.
Slab-on-Grade
$986-$1760
Slab homes can price differently when finished space, routing, or core drilling complicates the system path.
Crawl Space
$1548-$2830
Crawl-space jobs can move higher when vapor-barrier sealing, access, and sub-membrane suction add labor.
State rules that can change the quote
Disclosure: Required or commonly expected in this state context. Illinois requires sellers to disclose known radon test results to buyers under the Residential Real Property Disclosure Act.
Mitigation licensing: State licensing can add contractor and permit friction. Illinois requires radon mitigation professionals to be licensed by the Illinois Emergency Management Agency (IEMA).
EPA zone mix in Illinois
56
Zone 1
43
Zone 2
3
Zone 3
102 classified counties are used for state-level risk context. EPA zones do not replace a home test, but they help explain why county pages and confirmed 4.0+ results matter before comparing quotes.
Local cost guides
Illinois evidence-backed cost route
The cost directory follows the same eligibility rule as the county cost pages themselves. State hubs, sitemap candidates, and internal links point at pages Google can actually index.
102
Listed
102
Evidence
102
Measured
Best county pages to open first
Cook County
Evidence-backed local evidence
$1040-$1868
Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 20.6% 4.0+
Cook County is a strong cost page because it pairs Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 20.6% 4.0+ with a local housing base of 2,261,319 units and a modeled planning range of $1040-$1868.
DuPage County
Demand cohort local evidence
$1040-$1868
Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 34.9% 4.0+
DuPage County is a strong cost page because it pairs Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 34.9% 4.0+ with a local housing base of 365,347 units and a modeled planning range of $1040-$1868.
Lake County
Evidence-backed local evidence
$1040-$1868
Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 29.2% 4.0+
Lake County is a strong cost page because it pairs Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 29.2% 4.0+ with a local housing base of 269,416 units and a modeled planning range of $1040-$1868.
Will County
Demand cohort local evidence
$1040-$1868
Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 38.6% 4.0+
Will County is a strong cost page because it pairs Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 38.6% 4.0+ with a local housing base of 251,029 units and a modeled planning range of $1040-$1868.
Kane County
Evidence-backed local evidence
$1040-$1868
Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 38.8% 4.0+
Kane County is a strong cost page because it pairs Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 38.8% 4.0+ with a local housing base of 188,854 units and a modeled planning range of $1040-$1868.
Winnebago County
Evidence-backed local evidence
$1040-$1868
Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 36.7% 4.0+
Winnebago County is a strong cost page because it pairs Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 36.7% 4.0+ with a local housing base of 125,039 units and a modeled planning range of $1040-$1868.
McHenry County
Evidence-backed local evidence
$1040-$1868
Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 37.5% 4.0+
McHenry County is a strong cost page because it pairs Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 37.5% 4.0+ with a local housing base of 119,985 units and a modeled planning range of $1040-$1868.
Madison County
Demand cohort local evidence
$1040-$1868
Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 31.1% 4.0+
Madison County is a strong cost page because it pairs Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 31.1% 4.0+ with a local housing base of 118,715 units and a modeled planning range of $1040-$1868.
St. Clair County
Evidence-backed local evidence
$1040-$1868
Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 35.4% 4.0+
St. Clair County is a strong cost page because it pairs Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 35.4% 4.0+ with a local housing base of 115,165 units and a modeled planning range of $1040-$1868.
Champaign County
Demand cohort local evidence
$1040-$1868
Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 46.2% 4.0+
Champaign County is a strong cost page because it pairs Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 46.2% 4.0+ with a local housing base of 93,444 units and a modeled planning range of $1040-$1868.
Sangamon County
Demand cohort local evidence
$1040-$1868
Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 44.6% 4.0+
Sangamon County is a strong cost page because it pairs Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 44.6% 4.0+ with a local housing base of 92,938 units and a modeled planning range of $1040-$1868.
Peoria County
Evidence-backed local evidence
$1040-$1868
Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 43.6% 4.0+
Peoria County is a strong cost page because it pairs Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 43.6% 4.0+ with a local housing base of 84,963 units and a modeled planning range of $1040-$1868.
McLean County
Evidence-backed local evidence
$1040-$1868
Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 46% 4.0+
McLean County is a strong cost page because it pairs Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 46% 4.0+ with a local housing base of 74,822 units and a modeled planning range of $1040-$1868.
Rock Island County
Evidence-backed local evidence
$1040-$1868
Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 60.2% 4.0+
Rock Island County is a strong cost page because it pairs Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 60.2% 4.0+ with a local housing base of 66,731 units and a modeled planning range of $1040-$1868.
Tazewell County
Evidence-backed local evidence
$1040-$1868
Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 49.3% 4.0+
Tazewell County is a strong cost page because it pairs Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 49.3% 4.0+ with a local housing base of 58,634 units and a modeled planning range of $1040-$1868.
LaSalle County
Evidence-backed local evidence
$1040-$1868
Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 47.8% 4.0+
LaSalle County is a strong cost page because it pairs Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 47.8% 4.0+ with a local housing base of 49,796 units and a modeled planning range of $1040-$1868.
Macon County
Evidence-backed local evidence
$1040-$1868
Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 36.1% 4.0+
Macon County is a strong cost page because it pairs Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 36.1% 4.0+ with a local housing base of 49,757 units and a modeled planning range of $1040-$1868.
Kankakee County
Evidence-backed local evidence
$1040-$1868
Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 37.9% 4.0+
Kankakee County is a strong cost page because it pairs Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 37.9% 4.0+ with a local housing base of 45,312 units and a modeled planning range of $1040-$1868.
Kendall County
Evidence-backed local evidence
$1040-$1868
Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 39.6% 4.0+
Kendall County is a strong cost page because it pairs Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 39.6% 4.0+ with a local housing base of 45,078 units and a modeled planning range of $1040-$1868.
DeKalb County
Evidence-backed local evidence
$1040-$1868
Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 41% 4.0+
DeKalb County is a strong cost page because it pairs Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 41% 4.0+ with a local housing base of 41,399 units and a modeled planning range of $1040-$1868.
County estimates
Open a Illinois county page for local pricing
County pages narrow the state range with local EPA zone context, housing data, state rules, and the foundation scenario you choose.
Why Does Cost Vary in Illinois?
Price ranges across Illinois move with local labor rates, permit friction, roofline routing, and foundation type. County pages narrow this down for homeowners comparing basement, slab, or crawl space mitigation after a confirmed radon reading.