Buying or Selling a Home in Fort Collins? What to Know About Radon Disclosures

Buying or selling a home in Northern Colorado is an exciting milestone, but navigating the real estate transaction process comes with a long list of details. Along the Front Range, one critical detail you cannot afford to skip is radon.
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Because of our unique local geology, Colorado has some of the highest radon concentrations in the country. If you are preparing to buy or sell a property in Fort Collins, understanding how radon disclosures, home inspections, and mitigation negotiations work will keep your transaction smooth and your future home safe.

What Are Colorado’s Radon Disclosure Laws?

In 2023, the Colorado State Legislature passed Senate Bill 23-206 (SB23-206), which established strict radon disclosure requirements for real estate transactions and rental agreements.
Under this law, home sellers must provide buyers with a specific, written radon disclosure before a purchase contract becomes binding. This document outlines:

• The known presence of radon in the property.
• Any past radon testing records or reports.
• A warning statement explicitly highlighting the serious health risks of indoor radon exposure (which is the leading cause of lung cancer among non-smokers).

It is important to note that Colorado law does not legally mandate that a seller test a home for radon or install a mitigation system before selling. Instead, the law focuses heavily on transparency—ensuring the buyer is fully informed before closing the deal.

How Radon Testing Fits Into a Home Inspection

For buyers, a standard home inspection is your primary window into the property’s physical health. However, a general home inspector does not always include radon testing in their standard package. It is usually an add-on service, but one that is highly recommended.
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During a typical Fort Collins real estate transaction, the buyer schedules a home inspection within the specified contract objection deadlines. A continuous radon monitor is placed in the lowest livable level of the home (usually the basement) for a minimum of 48 hours.

If the test results come back showing levels at or above 4.0 picoCuries per liter (pCi/L)—the action limit set by the Environmental Protection Agency (EPA)—the buyer has the right to file a radon objection, asking the seller to address the issue.

Who Typically Pays for Radon Mitigation?

When elevated radon levels are found, the negotiation process begins. The question always arises: Who covers the cost of installing a radon mitigation system?

While everything in a real estate contract is negotiable, standard practice in Northern Colorado heavily leans on the seller paying for the mitigation system. Buyers expect a home to meet basic health and safety standards. Because an elevated radon level is considered a safety defect, sellers usually agree to cover the installation costs to keep the sale moving forward.

The Seller’s Options

• Hire a Registered Professional: The seller pays a licensed Colorado radon mitigation contractor to install a sub-slab depressurization system before the closing date.
• Offer a Credit: Alternatively, the seller can provide a financial credit to the buyer at closing, allowing the buyer to select their own contractor and handle the installation right after they move in.

Important Colorado Regulation: Under state law HB21-1195, any contractor performing radon testing or installing a mitigation system in Colorado must be formally certified by the National Radon Proficiency Program (NRPP) and registered with the Department of Regulatory Agencies (DORA). Whether you are a buyer or a seller, always verify that the professional you hire holds active state credentials.

Real Estate Advice for Buyers and Sellers

If you are selling: Consider doing a pre-listing radon test. Discovering high levels before your home goes on the market allows you to fix the problem on your own timeline, avoiding stressful, last-minute negotiations right before closing.
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If you are buying: Never skip the radon test, even if the home has a crawl space instead of a basement, or if it is a new construction build. If the home already has a mitigation system installed, ensure it is functioning properly by checking the system's pressure gauge (manometer) during your walkthrough.

Protecting Your Transaction and Your Health

Radon is a standard hurdle in Fort Collins real estate, but it shouldn't be a dealbreaker. With proper testing and professional mitigation, even exceptionally high radon levels can be safely brought down to minor levels, protecting your family’s lungs and securing your property investment for years to come.
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Do you have questions about an upcoming home inspection, or do you need to verify a system in your current home? Contact Fort Collins Radon Mitigation at 970-299-9763 to schedule a certified test or receive a custom mitigation estimate.

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