Radon Mitigation in Spokane, WA

Radon Mitigation in Spokane, Washington

Spokane County is in EPA Radon Zone 1 — the highest predicted indoor radon potential. While much of western Washington has lower radon levels, eastern Washington — particularly Spokane and surrounding counties — has some of the highest readings in the state, frequently between 4 and 10 pCi/L.

Why Eastern Washington Has Elevated Radon

The Columbia Plateau and surrounding Selkirk Mountains contain uranium-bearing granitic and metamorphic bedrock that continuously emits radon. Spokane sits on glacial till from the Missoula Floods overlying this radioactive basement rock, and the permeable gravel and sand let radon migrate efficiently into homes. The city's well-drained soils — great for foundations, bad for radon — accelerate gas movement into basements.

Neighborhood matters. South Hill, Comstock, and the older North Side neighborhoods have deeper basements and older foundations, which tend to test higher. Newer construction in Liberty Lake, Spokane Valley, and the West Plains is often better-sealed but still benefits from testing.

What Mitigation Costs in Spokane

Mitigation in Spokane typically runs $1,100 to $2,200. Standard scope:

• Sub-slab depressurization with one suction point
• PVC pipe routed through the home and vented above the roofline
• Certified radon fan (RP145 or XP201 are common choices)
• Post-installation test to confirm levels below 2 pCi/L

Cost factors:

• Basement vs crawl space: Crawl spaces in Spokane often need sub-membrane systems ($1,400-$2,200) due to high moisture
• Two suction points: Older basements with poor sub-slab communication may need a second point ($200-$300 extra)
• Finished basement: Common in South Hill — adds routing complexity ($300-$500)

Washington Certification Requirements

Washington recognizes NRPP and NRSB as the standard radon certification bodies. The state does not require additional licensing but the Department of Health maintains a referral list of certified professionals. Always verify certification on the NRPP or NRSB public database before signing a contract.

Getting Started

1. Test: Short-term test kits work fine for a first screen ($15-30). The Spokane Regional Health District offers discounted kits seasonally.
2. Compare quotes: Get bids from at least two certified mitigators — Spokane bids typically vary by $200-$400.
3. Install and verify: Most installations take one day. Always retest within 30 days.

Spokane Real Estate and Radon

Radon is increasingly part of Spokane home inspections. Buyers in South Hill, Manito, and Indian Trail commonly request radon testing during the inspection contingency. Sellers in higher-end neighborhoods often pre-mitigate to keep deals moving.

Spokane is Zone 1. Test your home and mitigate if you're above 4 pCi/L.