Colorado Radon Contractor License Lookup: How to Verify Before You Hire

Colorado's CDPHE Certification Requirement

Colorado's radon contractor certification program is administered by the Colorado Department of Public Health and Environment (CDPHE), Radiation Program. Under Colorado state rules, any person who performs radon mitigation services for compensation must hold a current CDPHE radon mitigation certification.

This is a meaningful requirement — not just a rubber-stamp. To obtain CDPHE certification, a radon mitigator must:

• Pass a written examination administered by a nationally recognized certification body (NRPP or NRSB)
• Demonstrate practical knowledge of AARST ANSI standards for radon mitigation
• Maintain continuing education credits for certification renewal (typically every 2 years)
• Register with CDPHE and pay the applicable certification fee

A contractor can hold national NRPP or NRSB certification but still not be CDPHE-registered if they haven't completed Colorado's state registration step. For Colorado work, both the national certification and the state registration are needed.

How to Look Up a Contractor's Certification in Colorado

There are two ways to verify a Colorado radon contractor's credentials. Use both for complete verification:

Step 1: CDPHE Colorado Radon Contractor Search

CDPHE maintains a searchable list of currently certified radon professionals in Colorado. The database is updated periodically and includes both mitigation contractors and measurement professionals (testers).

To search: Go to cdphe.colorado.gov → search "radon contractor certification list" or navigate to the Radiation Program section. The database can be searched by county or contractor name.

When reviewing the listing, confirm:

• The contractor's name matches exactly (not a similarly-named company)
• The certification is current (expiration date has not passed)
• The certification type is "mitigation" — not measurement only

Step 2: National Certification Database Cross-Check

Cross-check the contractor at the national level:

• NRPP: nrpp.info — click "Find a Certified Professional," enter the contractor's name or location
• NRSB: nrsb.org — click "Find Certified Professional"

A CDPHE-certified Colorado contractor should appear in one of these national databases as well. If they appear in CDPHE records but not nationally, ask the contractor to explain — they may have let their national certification lapse while maintaining state registration, which is technically possible but unusual for active contractors.

What Colorado CDPHE Certification Actually Means

CDPHE certification signals more than just passing a test. It means the contractor:

• Is required to install systems according to ANSI/AARST SGM-SF (the national radon mitigation standard)
• Must provide a post-mitigation test and document the results
• Must label the installed system with the date, their name, and certification number
• Is subject to complaint investigation by CDPHE if the work is substandard
• Can be decertified for repeated violations of installation standards

Hiring a certified contractor means you have recourse. If your system fails to reduce radon to below 4 pCi/L and the contractor is unresponsive, you can file a complaint with CDPHE, which has authority to investigate and impose penalties on certified contractors.

With an unlicensed contractor, your recourse is limited to civil litigation — you cannot report them to a licensing board because no such board governs them.

What to Do If a Contractor Isn't Listed

If you searched CDPHE and NRPP/NRSB and a contractor you were quoted by does not appear, here is the correct response:

1. Ask the contractor directly. There are legitimate reasons a contractor might not appear in a quick search: a recent name change, a database update lag, or a DBA (doing business as) name that differs from their certification name. Ask them to provide their CDPHE certification number and expiration date in writing.
2. Call CDPHE Radiation Program. CDPHE can confirm in real time whether a specific individual is currently certified. Call the CDPHE Radiation Program at (303) 692-3490.
3. If they remain unlisted, do not hire them. Colorado law requires certification for compensated radon mitigation work. Hiring an unlicensed contractor exposes you to an installation that may not meet standards and gives you no regulatory recourse.

Permit Requirements in Colorado

Colorado does not require a statewide building permit for radon mitigation in existing residential homes. However, electrical permits are required at the local level when the radon fan circuit involves new wiring, a new circuit, or a new outlet.

Key Colorado Municipalities

Your certified contractor should know whether a permit is required in your specific jurisdiction and will pull it before starting work. If they don't mention it and you're getting new electrical work, ask explicitly.

High-Radon Colorado Counties

Colorado has EPA Zone 1 and Zone 2 counties. Zone 1 counties have the highest predicted average indoor radon levels and the greatest urgency for testing and mitigation.

Zone designation is a starting point, not a guarantee. Homes in Zone 3 counties can still test high depending on local geology, soil permeability, and foundation type. Testing is the only way to know your specific home's radon level.

Frequently Asked Questions