Radon for Landlords

Radon Requirements for Colorado Landlords and Property Managers

Colorado residential landlords have written radon-disclosure responsibilities, and tenants may test their own rental units. When an elevated result is identified, the owner needs a documented response that combines tenant communication, licensed measurement, a property-specific mitigation plan, scheduling, records, and long-term system management.

This page summarizes the statewide framework created by SB23-206 and practical property-management steps. It is not a substitute for legal advice, the lease, local housing rules, or the current statute.

Request Rental Property Radon Support

Beginning August 7, 2023, Colorado landlords must provide prospective residential tenants a written radon warning, known radon history including tests, reports, and mitigation, and the current CDPHE real estate and rental brochure.

What the State Disclosure Framework Covers

Written warning about radon, testing, and mitigation
Known radon concentrations and history
Existing test results and reports
Mitigation or remediation already performed
Information about an installed radon system
The most recent CDPHE brochure for real estate and rental transactions

Maintain a standardized lease-disclosure package and update it when a new test, repair, mitigation system, or post-mitigation result is created. Do not rely on verbal disclosure or a generic statement that the building has a fan.

Tenant Testing and Elevated Results

Colorado law expressly allows a tenant to test the unit the tenant leases without obtaining a professional radon license. When a tenant reports an elevated result, preserve the report, confirm the device and conditions, communicate in writing, and obtain guidance from a Colorado-licensed Radon Measurement Professional and Radon Mitigation Professional as appropriate.

CDPHE explains that tenants may have lease remedies when the required disclosure is not provided or when a landlord does not make reasonable efforts to mitigate an elevated level after 180 days. After January 1, 2026, the statutory lease-void remedy is limited to leases longer than one year. Owners should obtain current legal advice because the remedy, habitability process, notice, access, and lease facts matter.

Do not wait for day 179 to begin. Testing confirmation, bids, owner approval, tenant notice, access, permits, materials, installation, and post-mitigation testing all require time.

A Practical Property-Management Response Plan

1
Receive and preserve the result
Record the unit, room, level, device, test dates, report, tenant communication, building conditions, and any existing system information.
2
Confirm the measurement strategy
A licensed measurement professional determines whether the reported result is sufficient for the next decision or whether follow-up testing is appropriate.
3
Evaluate the full building context
An elevated unit may share a slab, crawl space, foundation zone, passive stack, or mechanical condition with other units. The response should not assume the issue ends at the demising wall.
4
Obtain licensed mitigation proposals
Verify the responsible individual license in DORA and compare written scopes, tenant impacts, route, electrical, firestopping, post-testing, warranty, and schedule.
5
Communicate and document reasonable efforts
Provide notices, access requests, contractor dates, delays, approvals, invoices, reports, and completion records in writing according to counsel and property procedures.
6
Test and maintain
Complete the applicable post-mitigation measurement, provide relevant records, monitor the system, and schedule future retesting.

Why Licensed Vendors Matter for Rentals

State law

Professional radon measurement and mitigation are regulated occupations in Colorado. A maintenance employee, handyman, plumber, or general contractor is not automatically authorized to perform the radon scope.

Tenant safety and access

The system may cross occupied units, common areas, roofs, exterior walls, electrical systems, and fire-rated assemblies. Design and scheduling must account for occupants and future service.

Defensible records

Licensed reports and proposals identify responsible professionals, methods, system scope, test results, warranty, and operating information.

Portfolio consistency

A standardized licensed program prevents each site or maintenance technician from inventing a different testing or repair method.

Multifamily Portfolio Planning

Inventory every known test, system, fan, alarm, warranty, and post-mitigation result
Map ground-contact units and foundation zones
Prioritize buildings with no records, failed fans, tenant complaints, renovations, or older systems
Use the correct large-building measurement protocol rather than scattered convenience tests
Budget for fan replacement and system service over the ownership period
Create a tenant communication and access template
Retain reports and disclose known information to future tenants as required

Frequently Asked Questions

Create a Managed Radon Program

Drennen can help property managers organize testing, evaluate existing systems, prepare mitigation scopes, coordinate occupied-property work, document completion, and plan periodic retesting.

Request Property-Management Radon Support

Reviewed July 2026. This is general information, not legal advice. Review SB23-206, current Colorado statutes, the lease, local rules, and counsel before relying on a remedy or deadline.

Drennen Custom Contracting | Serving Fort Collins and Northern Colorado | 970-482-9100 | [email protected]