Radon Mitigation in Denver, CO: Costs, Contractors, and What to Expect

Why Denver Has a Serious Radon Problem

Denver's radon risk comes from the ground up — literally. The Colorado Front Range sits on a complex geology of granitic and metamorphic basement rock with elevated uranium content. As uranium decays, it produces radium, which produces radon gas. That gas travels through the soil and enters homes through the foundation.

Colorado's statewide average indoor radon concentration is approximately 6.4 pCi/L — the highest of any state in the continental US and nearly five times the national average of 1.3 pCi/L. Denver's close-in neighborhoods, built on the urban bedrock shelf, and the suburban foothills areas both see consistently elevated levels. Homes in Lakewood, Arvada, Westminster, Highlands Ranch, and Parker routinely test above 8–10 pCi/L.

Denver's Elevation Adds a Wrinkle

Denver's mile-high altitude creates tighter building pressure dynamics. At higher elevations, the pressure differential between indoor air and sub-slab soil gas is more pronounced — which accelerates radon entry. Homes are also better sealed for energy efficiency, reducing natural dilution. The combination means radon concentrations in Denver basements tend to be higher than the same house at lower elevation with similar geology.

What Mitigation Costs in Denver

Sub-slab depressurization — the EPA-recommended standard — costs $900–$1,800 for most Denver slab-on-grade homes. Variables that push cost higher:

• Finished basement: Additional drywall penetrations and interior pipe routing add $200–$400
• Multiple suction points: Homes with clay sub-slab or large footprints may need 2 suction points (+$300–$500)
• Crawl space component: Homes with partial crawl space require liner installation (+$400–$800)
• High-rise or condo: Shared-building mitigation is more complex and costs more

Denver has a competitive contractor market with dozens of NRPP-certified mitigators. Getting 2–3 quotes is easy and typically yields a $200–$400 spread in pricing.

Colorado's Radon Disclosure Requirements

Colorado requires sellers to disclose the results of any radon tests they're aware of. However, sellers aren't required to test — only to disclose results they already have. Many sellers have never tested.

As a buyer, include a radon test contingency in your offer, especially in:

• Pre-1990 homes (less air-sealing, more foundation gaps)
• Homes with finished basements (basement living space = more exposure hours)
• Any home in Jefferson County, Douglas County, or the foothills communities (elevated geology)

Post-mitigation testing 30 days after installation confirms the system is working. Denver contractors typically provide a post-mitigation test as part of the installation package.

Finding a Certified Mitigator in Denver

Colorado doesn't require state licensing for radon mitigators beyond NRPP or NRSB certification — but both certifications require passing exams and continuing education. When hiring:

• Verify NRPP or NRSB certification (search radonproficiency.org)
• Ask for references from recent Denver-area installations
• Request the post-mitigation test in writing before signing a contract
• Ask what fan model they'll use and why (XP201 for standard gravel, GX3+ for clay)

Find certified mitigators in Denver → | Colorado radon cost guide →