California 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 CA 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
California 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
California requires sellers to complete the Transfer Disclosure Statement (TDS), which covers known environmental hazards including radon.
Credential note
California does not require specific radon licensing. Look for NRPP or AARST-certified professionals.
CA Cost Starting Point
California cost range by foundation
Basement
$1050-$1855
Use this when the home has a basement or lowest-level slab that supports a standard sub-slab suction system.
Slab-on-Grade
$985-$1725
Slab homes can price differently when finished space, routing, or core drilling complicates the system path.
Crawl Space
$1580-$2850
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. California requires sellers to complete the Transfer Disclosure Statement (TDS), which covers known environmental hazards including radon.
Mitigation licensing: No state-specific mitigation license premium is modeled. California does not require specific radon licensing. Look for NRPP or AARST-certified professionals.
EPA zone mix in California
2
Zone 1
29
Zone 2
27
Zone 3
58 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
California 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.
58
Listed
58
Evidence
58
Measured
Best county pages to open first
Los Angeles County
Demand cohort local evidence
$1050-$1855
CDC EPHT Network Radon Tests from Labs: 9.5% 4.0+
Los Angeles County is a strong cost page because it pairs CDC EPHT Network Radon Tests from Labs: 9.5% 4.0+ with a local housing base of 3,599,561 units and a modeled planning range of $1050-$1855.
Riverside County
Evidence-backed local evidence
$1050-$1855
CDC EPHT Network Radon Tests from Labs: 1.3% 4.0+
Riverside County is a strong cost page because it pairs CDC EPHT Network Radon Tests from Labs: 1.3% 4.0+ with a local housing base of 851,646 units and a modeled planning range of $1050-$1855.
San Bernardino County
Evidence-backed local evidence
$1050-$1855
CDC EPHT Network Radon Tests from Labs: 4.5% 4.0+
San Bernardino County is a strong cost page because it pairs CDC EPHT Network Radon Tests from Labs: 4.5% 4.0+ with a local housing base of 733,104 units and a modeled planning range of $1050-$1855.
Santa Clara County
Demand cohort local evidence
$1050-$1855
CDC EPHT Network Radon Tests from Labs: 9.2% 4.0+
Santa Clara County is a strong cost page because it pairs CDC EPHT Network Radon Tests from Labs: 9.2% 4.0+ with a local housing base of 688,287 units and a modeled planning range of $1050-$1855.
Alameda County
Evidence-backed local evidence
$1050-$1855
CDC EPHT Network Radon Tests from Labs: 6.7% 4.0+
Alameda County is a strong cost page because it pairs CDC EPHT Network Radon Tests from Labs: 6.7% 4.0+ with a local housing base of 622,856 units and a modeled planning range of $1050-$1855.
Contra Costa County
Evidence-backed local evidence
$1050-$1855
CDC EPHT Network Radon Tests from Labs: 8.8% 4.0+
Contra Costa County is a strong cost page because it pairs CDC EPHT Network Radon Tests from Labs: 8.8% 4.0+ with a local housing base of 424,057 units and a modeled planning range of $1050-$1855.
San Francisco County
Evidence-backed local evidence
$1050-$1855
CDC EPHT Network Radon Tests from Labs: 2.8% 4.0+
San Francisco County is a strong cost page because it pairs CDC EPHT Network Radon Tests from Labs: 2.8% 4.0+ with a local housing base of 408,198 units and a modeled planning range of $1050-$1855.
Fresno County
Evidence-backed local evidence
$1050-$1855
CDC EPHT Network Radon Tests from Labs: 11% 4.0+
Fresno County is a strong cost page because it pairs CDC EPHT Network Radon Tests from Labs: 11% 4.0+ with a local housing base of 339,270 units and a modeled planning range of $1050-$1855.
Kern County
Evidence-backed local evidence
$1050-$1855
CDC EPHT Network Radon Tests from Labs: 11.6% 4.0+
Kern County is a strong cost page because it pairs CDC EPHT Network Radon Tests from Labs: 11.6% 4.0+ with a local housing base of 301,687 units and a modeled planning range of $1050-$1855.
Ventura County
Evidence-backed local evidence
$1050-$1855
CDC EPHT Network Radon Tests from Labs: 11.9% 4.0+
Ventura County is a strong cost page because it pairs CDC EPHT Network Radon Tests from Labs: 11.9% 4.0+ with a local housing base of 293,491 units and a modeled planning range of $1050-$1855.
San Mateo County
Evidence-backed local evidence
$1050-$1855
CDC EPHT Network Radon Tests from Labs: 9.2% 4.0+
San Mateo County is a strong cost page because it pairs CDC EPHT Network Radon Tests from Labs: 9.2% 4.0+ with a local housing base of 284,211 units and a modeled planning range of $1050-$1855.
Santa Barbara County
Demand cohort local evidence
$1050-$1855
CDC EPHT Network Radon Tests from Labs: 17.6% 4.0+
Santa Barbara County is a strong cost page because it pairs CDC EPHT Network Radon Tests from Labs: 17.6% 4.0+ with a local housing base of 158,807 units and a modeled planning range of $1050-$1855.
Tulare County
Evidence-backed local evidence
$1050-$1855
CDC EPHT Network Radon Tests from Labs: 23.8% 4.0+
Tulare County is a strong cost page because it pairs CDC EPHT Network Radon Tests from Labs: 23.8% 4.0+ with a local housing base of 151,190 units and a modeled planning range of $1050-$1855.
Monterey County
Evidence-backed local evidence
$1050-$1855
CDC EPHT Network Radon Tests from Labs: 14.9% 4.0+
Monterey County is a strong cost page because it pairs CDC EPHT Network Radon Tests from Labs: 14.9% 4.0+ with a local housing base of 143,743 units and a modeled planning range of $1050-$1855.
San Luis Obispo County
Evidence-backed local evidence
$1050-$1855
CDC EPHT Network Radon Tests from Labs: 12.5% 4.0+
San Luis Obispo County is a strong cost page because it pairs CDC EPHT Network Radon Tests from Labs: 12.5% 4.0+ with a local housing base of 123,968 units and a modeled planning range of $1050-$1855.
Santa Cruz County
Evidence-backed local evidence
$1050-$1855
CDC EPHT Network Radon Tests from Labs: 21.9% 4.0+
Santa Cruz County is a strong cost page because it pairs CDC EPHT Network Radon Tests from Labs: 21.9% 4.0+ with a local housing base of 106,433 units and a modeled planning range of $1050-$1855.
El Dorado County
Evidence-backed local evidence
$1050-$1855
CDC EPHT Network Radon Tests from Labs: 30.3% 4.0+
El Dorado County is a strong cost page because it pairs CDC EPHT Network Radon Tests from Labs: 30.3% 4.0+ with a local housing base of 93,679 units and a modeled planning range of $1050-$1855.
Nevada County
Evidence-backed local evidence
$1050-$1855
CDC EPHT Network Radon Tests from Labs: 25% 4.0+
Nevada County is a strong cost page because it pairs CDC EPHT Network Radon Tests from Labs: 25% 4.0+ with a local housing base of 53,690 units and a modeled planning range of $1050-$1855.
Placer County
Evidence-backed local evidence
$1050-$1855
CDC EPHT Network Radon Tests from Labs: 7.4% 4.0+
Placer County is a strong cost page because it pairs CDC EPHT Network Radon Tests from Labs: 7.4% 4.0+ with a local housing base of 173,090 units and a modeled planning range of $1050-$1855.
San Diego County
Evidence-backed local evidence
$1050-$1855
CDC EPHT Network Radon Tests from Labs: 2.6% 4.0+
San Diego County is a strong cost page because it pairs CDC EPHT Network Radon Tests from Labs: 2.6% 4.0+ with a local housing base of 1,230,349 units and a modeled planning range of $1050-$1855.
County estimates
Open a California 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 California?
Price ranges across California 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.