Colorado homeowners and buyers are becoming increasingly aware of a critical health risk hiding beneath their homes: radon gas. Radon is a naturally occurring radioactive gas that seeps into homes through cracks in the foundation, slabs, crawlspaces, and plumbing penetrations. It's colorless, odorless, and tasteless—making it undetectable without proper testing.
Why does this matter in Colorado? Because our entire state lies within EPA Radon Zone 1, meaning we have some of the highest average indoor radon levels in the U.S. In fact, more than 50% of homes in Colorado test above the EPA's recommended action level of 4.0 pCi/L.
In this article, we’re diving into the importance of radon testing and mitigation during home inspections in Colorado. Whether you're buying, selling, or maintaining a property, here's what you need to know.
Why Radon Is a Serious Concern in Colorado
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High Elevation + Geology = High Risk: Colorado's geology makes it a hotspot for radon release. Because of our elevation and soil composition, radon gas escapes more easily and accumulates in homes at unsafe levels.
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Lung Cancer Risk: Radon is the second leading cause of lung cancer in the U.S., following smoking. Long-term exposure—even to moderately elevated levels—can significantly increase health risks.
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Widespread Presence: The Colorado Department of Public Health and Environment (CDPHE) has found that radon levels average around 6.3 pCi/L across the state, well above national averages.
Radon and Colorado Real Estate Law
Recent legislation in Colorado has made radon testing and disclosure more important than ever:
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HB21-1195: As of 2022, radon measurement and mitigation professionals in Colorado must be licensed through the Department of Regulatory Agencies (DORA). This law ensures that only trained, certified professionals can legally test or mitigate radon in residential properties.
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SB23-206: Effective August 2023, this bill requires sellers and landlords to disclose any known radon testing results, mitigation systems, and potential risks. It also requires them to provide educational materials to buyers and tenants.
What does this mean for homebuyers?
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Always request radon test results during the inspection process.
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If results are unavailable, consider testing as part of your due diligence.
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If radon levels exceed 4.0 pCi/L, negotiate for mitigation before closing.
For sellers:
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Be prepared to disclose any known radon test results.
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If mitigation systems are in place, ensure they’re documented and functioning.
What Radon Testing Involves
Short-Term vs. Long-Term Testing
Certified inspectors typically use continuous radon monitors (CRMs), charcoal canisters, or alpha-track detectors.
Where to Test
Testing should occur in the lowest level of the home that is regularly used—often basements or ground-level living areas.
What to Do If Radon Levels Are High
If your radon test results come back at or above 4.0 pCi/L, it’s time to take action.
Common Mitigation Techniques
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Sub-Slab Depressurization: The most common system. A pipe is inserted through the basement floor and connected to a fan that vents radon gas outside the home.
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Sump Pit Suction: For homes with sump pumps, this system can draw radon from beneath the slab through the sump basin.
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Crawlspace Ventilation: Installing a vapor barrier and using fans to vent gas from crawlspaces.
Costs
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Radon mitigation typically costs between $800–$1,500, depending on the size of the home and system complexity.
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Annual maintenance costs are minimal, often under $150.
Post-Mitigation Testing
Once a system is installed, retesting is essential to confirm effectiveness. The EPA recommends retesting every two years to ensure ongoing safety.
Common Questions About Radon in Colorado
Is radon testing required by law in Colorado? No, testing itself is not legally required for every home sale. However, disclosure is required if radon testing has been conducted and results are known.
What is a safe radon level? The EPA recommends mitigation if levels are at or above 4.0 pCi/L. Ideal levels are under 2.0 pCi/L.
Can new homes have high radon levels? Yes. Even homes built with passive radon systems can still have elevated levels. Testing is necessary regardless of age, style, or location.
How often should I test for radon? Every 2 years, or after major renovations that affect the foundation or ventilation.
Will a mitigation system affect home value? Not negatively. In fact, buyers often see a radon mitigation system as a value-add, knowing the home is already protected.
Why Every Home Inspection in Colorado Should Include Radon Testing
Radon isn’t just another box to check—it’s a health and safety issue that impacts every homeowner and future occupant. Because Colorado has such high levels statewide, every home inspection should include a radon test.
Including radon testing during inspections:
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Protects buyers from unknown health risks.
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Helps sellers avoid future liability.
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Ensures transparency in every real estate transaction.
At Steel Rhino Property Inspections, we include radon testing in many of our home inspections or offer it as an easy add-on. Our inspectors use certified testing methods and provide fast, reliable results—so you can make informed decisions.
Radon is invisible, but its risks are very real. If you’re buying, selling, or simply living in a home in Colorado, it’s time to take radon seriously. The good news? Testing is quick, affordable, and highly effective when performed by certified professionals.
Have questions about radon testing or want to schedule your inspection? Contact Steel Rhino today. We’re here to make sure your home is not only safe—but radon-free.
Steel Rhino Property Inspections
Your trusted experts for Colorado home inspections
Radon is a toxic gas that can be found in any house, old or new. It can enter your Colorado home through leaks in your foundation or porous building materials. Unfortunately,