Radon in Maricopa County, AZ: Testing and Mitigation Cost

Radon is not only a basement-state problem. EPA's 1993 Map of Radon Zones rates Maricopa County Zone 2, meaning a predicted county average indoor screening level of 2 to 4 pCi/L, the range where EPA says to consider fixing a home. EPA's file puts every one of Arizona's 15 counties in Zone 2.

The Census Bureau relationship file maps 135 ZIP areas to Maricopa County, and all of them fall in Zone 2 counties. Arizona does not publish ZIP or county test results the way Pennsylvania and Ohio do, so the only way to know a Phoenix-area home's level is to test it (EPA Citizen's Guide, 2016).

Most Valley homes are built slab-on-grade. HomeGuide's Feb 2026 survey prices a sub-slab depressurization system at $1,200 to $2,000 installed, the method EPA's Consumer's Guide lists first for slab homes.

Licensing and permits

No state radon license: Arizona does not license radon testers or mitigators as a separate trade, and the Arizona Department of Health Services radon program provides public information rather than certification. Ask for national certification (NRPP or NRSB).

Contractor license: the Arizona Registrar of Contractors licenses contractors who alter or repair buildings, and state law (A.R.S. § 32-1121) limits the handyman exemption for larger jobs and jobs needing a permit. A typical radon system priced at $1,200 or more should be done by an ROC-licensed contractor.

City permits: Phoenix, Mesa, Scottsdale and the other cities each run their own permit desks; an electrical permit may apply to the fan circuit. HomeGuide puts radon permits at $25 to $150 where required.

Keep the post-mitigation test with the house records.

Local conditions

The Valley floor is basin-fill alluvium, sand, gravel and clay washed down from mountain ranges of granite and other crystalline rock such as South Mountain and the McDowell Mountains. Granite can carry uranium, and coarse gravel lets soil gas travel, two of the inputs EPA's zone method weighed.

Slab-on-grade construction dominates the metro's tract homes. A cracked slab, plumbing penetrations and expansion joints give soil gas a path indoors, which is where sub-slab suction pulls it back out.

Desert heat matters too: homes sealed tight and air-conditioned much of the year exchange less air with the outdoors, so test with windows closed as EPA's protocols describe.

What drives local prices

Slab homes usually need one or two suction points through the slab, $1,200 to $2,000 based on HomeGuide's published survey; each extra point is an est. $250 to $500 in our calculator.
Pipe route in single-story homes: running the pipe through the garage and attic is common in the county and is an est. ×1.15 in our calculator.
Larger homes of 2,500 sq ft or more in Scottsdale, Gilbert and north Phoenix may need more suction (est. ×1.25).
Permit $25 to $150 and professional retest $125 to $400 (HomeGuide).
Fewer specialist firms than in high-radon states can mean general contractors bid the work; ask for national radon certification (our observation).

Common jobs

Sub-slab systems in single-story slab homes, routed through the garage.
Sealing slab cracks and plumbing penetrations as part of a system.
Pre-sale tests for relocating buyers who expect radon results.
Retests after remodels that cut into the slab.

From test to fixed, and where we cover

Step 1: test with windows and doors closed. Step 2: at 4 pCi/L or more, get two bids from nationally certified mitigators with an ROC license.

Step 3: compare them with the calculator. Step 4: retest after installation.

We take requests across the county: Phoenix, Mesa, Chandler, Gilbert, Scottsdale, Tempe, Glendale, Peoria, Surprise and Goodyear, along I-10, I-17, Loop 101 and Loop 202.

Communities: Phoenix, Mesa, Chandler, Gilbert, Scottsdale, Tempe, Glendale, Peoria, Surprise, Goodyear

Before you sign

A Zone 2 county still has homes above 4 pCi/L; EPA's advice is to test and fix on a timeline of weeks (EPA Citizen's Guide). Compare at least two written bids.

Questions about Maricopa County

Is there radon in Phoenix?

EPA rates Maricopa County Zone 2, a predicted average of 2 to 4 pCi/L, and finds elevated homes in every zone. Only a test tells you your level.

Do slab homes get radon?

Yes. Soil gas enters through slab cracks and penetrations; EPA's Consumer's Guide lists sub-slab suction as the standard fix.

Does Arizona license radon mitigators?

Not as a separate trade. Ask for NRPP or NRSB certification and an Arizona ROC contractor license.

What does mitigation cost in Maricopa County?

HomeGuide's national range for a sub-slab system is $1,200 to $2,000.

Sources

Rules and fees change; confirm with the state radon office. Price your own system with the radon mitigation cost calculator, read the radon mitigation cost guide, or check any ZIP with the radon levels by ZIP tool.