You failed a radon test in the Denver metro
An elevated reading anywhere along the Front Range is a common outcome — Colorado reads high across most of its counties. Confirm the number, get certified bidders in front of it, and negotiate from a written design.
The distinctive local question is the structural floor: homeowners in Highlands Ranch and the southern suburbs discover they have a void beneath the main level rather than a slab, and want to know what that means. It means the mitigation approach differs — the void is depressurized or a membrane is applied — and it means a standard slab quote does not describe their house.
What an elevated result actually means
Confirm in the same location under closed-building conditions. Front Range pressure swings make short-term results noisier here than in steadier climates, so a confirming measurement genuinely adds information rather than being a formality. If a sale is running, confirm and quote in parallel. Colorado issues no state radon license and no Colorado statute compels mitigation at any reading — verify NRPP or NRSB certification, and treat the result as the negotiable repair item it is. Front Range winters are cold but dry and sunny, and the heating season still produces the strongest stack effect and the most conservative closed-house readings. Colorado’s wide daily temperature swings drive pressure changes through a house, which makes short-term results noisier here than in more stable climates — an argument for confirming borderline numbers.
Your next four steps
Four steps, in this order. Confirm the result — a second short-term test or a longer-term measurement, run under closed-building conditions. Get written quotes from independent businesses holding a current NRPP or NRSB mitigation certification. Decide who pays, which in Colorado is a negotiation and not a legal mandate. Then verify with a post-mitigation test after the system runs. Nothing about a single elevated reading forces you out of your house or out of a contract. Ask for the post-mitigation measurement after at least twenty-four hours of runtime, in the original detector location, in writing, with the contractor’s current NRPP or NRSB certification identified on the same page. Where a structural-floor void or crawlspace was treated, confirm the verification measurement was taken in the living space above it.
If the result landed inside a deal
Colorado requires sellers of residential real property to give buyers a radon warning statement and the state’s radon brochure before a sale, and the standard seller’s property disclosure addresses radon testing and mitigation. Colorado does not require a seller to test or to mitigate — the response to an elevated result is negotiated like any other inspection finding.
Communities we route in Denver Metro
Failed Radon Test questions in Denver Metro
Colorado has no radon licensing. How do I know a contractor is legitimate?
Ask for a current NRPP or NRSB certification and confirm it directly rather than accepting a claim. Then read the quote: a designed system identifies your foundation type, names suction point locations, describes what pressure-field or diagnostic testing found, specifies the fan, lists sealing or membrane scope, and prices the post-mitigation verification test. Specificity is harder to fake than a credential badge.
Does an elevated result put a sale in the Denver metro at risk?
Colorado does not license radon professionals at the state level; the state program directs homeowners to nationally certified professionals credentialed through NRPP or NRSB. Radon appears routinely in Front Range inspections, and elevated results are negotiated as ordinary repair items — no Colorado statute compels a seller to mitigate at any concentration.
Am I legally required to mitigate in Colorado?
No. A result at or above 4 pCi/L is an EPA action recommendation, not an automatic legal obligation in a Colorado sale. What state law generally governs is disclosure — telling a buyer what you know — not whether a system gets installed. Who pays, and whether the work happens before closing, is negotiated between buyer and seller.
Related Denver Metro guides
- Radon mitigation in Denver Metro
- Radon testing in Denver Metro
- Mitigation cost in Denver Metro
- System installation in Denver Metro
- Colorado radon contractors: join our network
Decision guides for this stage
- Failed a test during an inspection
- Negotiating radon repairs
- Buyer credit vs seller mitigation
- All homeowner decision guides
An elevated number in the Denver metro is a solvable building problem with a known fix and a verifiable result. Work the four steps, keep the paperwork, and let the 3 territories here put competing quotes in front of you rather than one.
Sources
- U.S. EPA — Radon
- U.S. EPA — A Citizen’s Guide to Radon
- U.S. EPA — Consumer’s Guide to Radon Reduction
- U.S. EPA — EPA Map of Radon Zones
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