If you have ever bought or sold a home in Colorado and someone mentioned radon, you probably nodded along and hoped it would just sort itself out. Radon testing gets treated like a formality in a lot of transactions — a box to check before closing — but in Colorado, it is genuinely one of the more important steps in understanding what you are getting into. The state consistently ranks among the highest in the country for radon exposure, and the gas itself has no smell, no color, and no warning label. It does its thing quietly, which is exactly what makes it worth taking seriously.
What radon actually is (and why Colorado has so much of it)
Radon is a naturally occurring radioactive gas that forms when uranium in soil and rock breaks down. It seeps up through the ground and into buildings through foundation cracks, gaps around pipes, and construction joints. Outside, it disperses harmlessly into the air. Inside a home, it accumulates — and the more time you spend in that home, the more exposure adds up.
Colorado’s geology is a big part of why radon levels here run higher than the national average. The soil composition across the Front Range and much of the state creates conditions where radon production is elevated. The EPA considers any level at or above 4 picocuries per liter to be actionable, and a significant portion of Colorado homes test above that threshold. Many test well above it.
Why basements change the math
Colorado homeowners love their basements, and basements are where radon tends to concentrate most. Lower floors have more contact with the ground, less natural ventilation, and often the longest occupancy time — home offices, bedrooms, playrooms. If you are spending hours each day in a finished basement and that space has not been tested, you simply do not know what you are breathing.
How radon testing works
Radon testing is not complicated or invasive. A certified radon tester places a monitor in the lowest livable area of the home — typically the basement or lowest floor — and lets it collect data over a defined period. Short-term tests run between two and seven days. Long-term tests run ninety days or more and give a fuller picture of average exposure across different seasons and conditions.
At Stauss Inspections, radon testing is performed by a certified radon tester, which matters more than it might sound. Certification means the test follows established protocols for placement, timing, and conditions, closed-house conditions are required during testing to get an accurate reading. A properly conducted test gives you reliable numbers. A sloppily conducted one gives you false confidence.
What happens if levels come back high
A high radon result is not a dealbreaker. It is information. Radon mitigation systems — typically a pipe and fan system that draws radon from beneath the foundation and vents it outside — are well-established, widely available, and usually cost between $800 and $2,500 depending on the home. They work. Post-mitigation testing routinely shows dramatic reductions, often bringing levels well below the EPA action threshold.
In a real estate transaction, a high radon reading becomes a negotiating point. The buyer can request mitigation as a condition of closing, or the parties can negotiate a credit. Either way, knowing the number before you close puts you in a far better position than finding out after you have moved in.
Radon testing for sellers: the proactive move
Pre-listing radon testing is one of the smartest things a Colorado seller can do before putting a home on the market. If levels are elevated, you can address it before buyers ever see a number. A home with a functioning mitigation system and a clean post-mitigation test is a stronger listing than one where radon is an open question. It removes uncertainty from the transaction and positions you as a seller who has done their homework.
Buyers in competitive markets also tend to move faster when they are not waiting on test results or negotiating remediation credits. Getting ahead of radon is one of those moves that costs relatively little and removes friction at exactly the moment you want everything to go smoothly.
Frequently Asked Questions (FAQ)
How long does radon testing take?
Short-term tests typically run between two and seven days under closed-house conditions. Results are usually available within 24 to 48 hours of the monitor being retrieved and analyzed. Long-term tests run 90 days or more and are better suited for homeowners who want a seasonal average rather than a snapshot.
Is radon testing required when buying a home in Colorado?
It is not legally required, but it is strongly recommended and extremely common in Colorado transactions. Given the state’s elevated radon levels, skipping the test means accepting unknown risk. Most experienced buyers’ agents will encourage it as a standard part of due diligence.
Can I test for radon myself?
DIY test kits are available at hardware stores, but there are meaningful differences between a consumer kit and a professionally conducted radon test. Certified testing follows specific protocols for placement, timing, and conditions that affect the reliability of results. For a real estate transaction or a decision about mitigation, professional testing gives you defensible, accurate numbers.
What is the EPA’s action level for radon?
The EPA recommends taking action to reduce radon when levels reach 4 picocuries per liter (pCi/L) or higher. They also suggest considering mitigation for levels between 2 and 4 pCi/L, particularly in homes where significant time is spent on lower floors.
Does a radon mitigation system affect home value?
A properly installed and functioning mitigation system is generally viewed positively by buyers. It signals that the issue has been identified and addressed, which is preferable to an untested home or one with a known problem and no solution in place.
Stauss Inspections is proudly serving Arvada, Denver, and the Colorado Front Range.
