Radon for Realtors
Colorado Radon Requirements for Realtors
Radon can affect contract deadlines, inspection objections, repair negotiations, lender or insurer questions, and the documentation delivered at closing. Colorado now regulates both the people who perform professional radon work and the disclosures used in residential real estate transactions.
This page gives real estate professionals a practical framework for managing radon without acting as a scientist, contractor, or attorney. The central rule is simple: use the current Commission-approved forms and CDPHE brochure, recommend valid testing, and refer measurement and mitigation work only to properly licensed Colorado radon professionals.
Colorado law has required radon measurement and mitigation professionals to hold a state license since July 1, 2022, unless a narrow statutory exemption applies. A national certification, home-inspector credential, plumbing license, electrical license, or general contractor license does not replace the required Colorado radon license.
The Two Colorado Rules Realtors Need to Separate
Transaction Disclosure Requirements
SB23-206 requires residential sales contracts to contain the statutory radon warning and requires disclosure of known testing, results, reports, mitigation, and installed-system information, together with the current CDPHE real estate brochure. Commission-approved forms were updated for brokered transactions.
Professional Licensing Requirements
Professional testing must be performed by, or under the lawful measurement program of, a Colorado-licensed Radon Measurement Professional. Mitigation design, installation, repair, and modification must be performed by, or under the required direct supervision of, a Colorado-licensed Radon Mitigation Professional.
The disclosure law does not create a universal state requirement that every residential sale include a radon test. It does require the warning and known-information disclosures. Testing is strongly recommended, and a licensed professional is the safest way to obtain a defensible transaction result.
What SB23-206 Requires in Residential Sales
- A bold warning about radon risk, testing, and mitigation in the residential sales contract or substantially similar compliant language
- Disclosure of whether radon testing has been performed
- The most recent available records or reports concerning radon concentrations
- A description of detected concentrations and any mitigation or remediation performed
- Information about an installed radon mitigation system
- Delivery of the most recent CDPHE brochure concerning radon in real estate transactions
Use the current Colorado Real Estate Commission-approved forms and your brokerage procedures. When facts are uncertain, do not guess or rewrite technical findings. Ask the seller for existing reports and system documentation, and refer legal questions to the managing broker or counsel.
Why an Unlicensed Radon Vendor Creates Transaction Risk
The work may be unlawful
Colorado prohibits individuals from practicing professional radon measurement or mitigation without the applicable license unless an exemption applies. A paid contractor cannot rely on the owner-occupant do-it-yourself exemption.
The test may be challenged
Improper device selection, placement, timing, closed-building conditions, quality control, or reporting can undermine confidence in the result and create a dispute near closing.
The system may not meet adopted standards
Colorado requires licensed professionals to follow the applicable standards incorporated in 4 CCR 754-1. A system that only looks complete may have an unsafe fan location, poor discharge, missing monitoring, inadequate crawl membrane, disconnected foundation zones, or an ineffective passive rough-in.
Documentation may be incomplete
A transaction file should clearly identify the responsible licensed professional, test result, system scope, post-mitigation result, warranty, and operating instructions. Missing records can follow the property into the next transaction.
The referral can damage trust
The broker does not need to guarantee a contractor, but referring an unlicensed provider after Colorado created a searchable license program can create avoidable client, brokerage, and reputation risk.
How to Verify a Radon Professional
- 1
Ask for the individual license number
Colorado radon licenses are issued to individuals. For testing, look for an active Radon Measurement Professional license. For installation or repair, look for an active Radon Mitigation Professional license.
- 2
Verify it in the DORA lookup
Do not rely only on a logo, certificate image, old proposal, or website statement. Search the current Colorado DORA record and confirm active status. Radon licenses expire annually on May 31 unless renewed.
- 3
Identify who will be responsible on site
If installers or technicians are not individually licensed, ask which licensed mitigation professional is providing the direct supervision required by law. A remote signature after completion is not a substitute for lawful supervision.
- 4
Confirm the right license for the task
Measurement and mitigation are separate regulated practices. A vendor may hold one license and not the other.
- 5
Review the written report or proposal
The document should identify the professional, property, result or scope, standards, assumptions, monitoring, post-testing, and warranty. Avoid cash-only arrangements with no documentation.
A Clean Radon Transaction Workflow
- 1
Before inspection
Provide the required disclosure materials, ask for existing test and system records, identify transaction deadlines, and schedule a licensed test early enough to avoid emergency decisions.
- 2
During testing
Maintain closed-building conditions, protect the device from interference, document access, and avoid asking parties to alter normal operation outside the test protocol.
- 3
When the result is elevated
Obtain a written mitigation proposal from a licensed professional. Decide through the contract whether the seller will install, provide a credit, escrow funds, or take another negotiated approach.
- 4
Before installation
Confirm property-owner authorization, route preferences, electrical access, HOA or exterior constraints, closing date, and who can approve change orders.
- 5
After installation
Obtain the system documentation, current warranty, operating instructions, post-mitigation result, paid invoice if required, and any permit or inspection records.
- 6
At closing
Ensure the radon records that should remain with the property are delivered to the buyer. Do not allow a fan to be unplugged or a monitoring device to be removed during move-out.
Common Realtor Questions
Realtor Radon Checklist
- Use the current Commission-approved contract and seller-disclosure forms
- Deliver the current CDPHE radon and real estate brochure
- Request all existing test reports, mitigation documents, warranties, and operating instructions
- Schedule testing with an active Colorado Radon Measurement Professional
- Request mitigation only from an active Colorado Radon Mitigation Professional
- Verify the responsible individual in DORA rather than relying on a company name
- Build enough time for installation and post-mitigation testing before closing
- Keep technical conclusions with the licensed professional and legal conclusions with the broker or counsel
Drennen Support for Northern Colorado Real Estate Professionals
Drennen provides licensed measurement, mitigation estimates, passive-system activation, crawl-space systems, repairs, post-mitigation testing, and transaction documentation. Our office can coordinate with the buyer, seller, broker, property manager, inspector, and access contact while keeping the responsible parties informed.
Reviewed July 2026. This page is general education and is not legal advice, a substitute for Commission-approved forms, or a statement of brokerage duties in a particular transaction. Laws, forms, rules, and license status change. Consult the current Colorado Division of Real Estate, DORA, CDPHE, your managing broker, and legal counsel.
Drennen Custom Contracting | Serving Fort Collins and Northern Colorado | 970-482-9100 | [email protected]