How to Choose a Radon Mitigation Contractor in Colorado

Hiring a radon mitigation contractor in Colorado is different from hiring most contractors. Colorado is one of the few states with state-level radon contractor licensing — every legitimate mitigator has a license number you can look up in 30 seconds. That changes the dynamic. You're not picking from a stack of business cards and hoping for the best; you're verifying credentials, comparing scopes, and making a defensible choice.

This page is the top-level guide: what credentials to check, what to ask, what to compare, and what to walk away from. Each link in the section below goes deeper.

A legitimate Colorado radon mitigation contractor will have:

1. A current DORA radon mitigation license. Issued by Colorado DORA's Office of Radon Professionals (4 CCR 754-1). Required by law since July 1, 2022. Verifiable through the public license lookup.^[1]
2. NRPP or NRSB certification. National Radon Proficiency Program or National Radon Safety Board. Voluntary nationally but required by CDPHE guidance for Colorado-licensed mitigators. Verifiable through each program's public directory.^[2]

If a contractor can't provide both numbers, don't hire them. Not negotiable. The DORA license alone takes care of the legal requirement; the NRPP or NRSB certification confirms they actually know the AARST standards for designing a working system.

Step-by-step license verification walkthrough →

• Years in business. 5+ years is a reasonable threshold; 10+ is preferred. New companies aren't automatically bad, but established ones have a track record.
• BBB profile. Check for complaints, their pattern, and the contractor's responses.
• Online reviews. Google reviews, Yelp, Angi. Read the negative reviews and look at the contractor's response — that often tells you more than the positive ones.
• References. Ask for three recent customer references. A reputable contractor will provide them.
• Liability insurance. $1M general liability is typical. Confirm in writing.
• Workers' compensation. Confirms the contractor follows Colorado labor law and protects you if a worker is injured on your property.
• Written estimate. Never accept a quote that isn't in writing. Quote checklist →

A typical hiring sequence for Colorado mitigation:

1. Phone screen. Verify the DORA and NRPP/NRSB numbers, confirm they service your ZIP code, ask about availability. (~10 minutes per contractor.)
2. In-home assessment. The contractor walks the basement (or crawlspace) with you, asks about your test result, identifies the foundation type and obvious challenges. Should take 30–60 minutes. Reputable contractors don't charge for this.
3. Written quote. Detailed scope per the quote checklist. Usually delivered within 1–3 days.
4. Follow-up questions. If anything's unclear or different from another quote, ask. A contractor who can't or won't explain technical choices is a contractor to avoid.
5. References. Call at least one reference before signing. Ask about the install experience, whether the post-mitigation test result was as promised, and how the warranty has held up.
6. Sign and schedule. Most installs happen 1–2 weeks after signing.

Full pre-hire question list →

Get at least two written quotes for any Colorado mitigation install, three for anything complex (crawlspace, multi-zone, finished basement with aesthetic concerns). When comparing:

• Compare scope, not just bottom-line price. A $1,400 quote and a $2,200 quote can both be honest if the scopes differ.
• Match foundation work, suction point count, fan model, sealing scope, pipe routing, exhaust point, manometer install, warranty, and post-mitigation test.
• Read the warranty language carefully.
• Ask each contractor what's pushing their price above or below the four-scenario framework.

Five real cost drivers behind quote variation → · Quote sanity-check tree →

• No DORA license number, or refuses to provide one.
• No NRPP or NRSB certification.
• Cash-only payment.
• Won't put scope details in writing.
• Pressure tactics or "this price is good for today only."
• "Required" upgrades that the contractor can't explain technically.
• Refuses to provide references.
• Won't include a post-mitigation test in the quote.
• No written warranty.

Full red flags walkthrough →

A typical Colorado mitigation install:

• Install day: 4–8 hours on site for a basic basement; longer for crawlspace or multi-zone. The contractor cores the suction point, runs the pipe, installs the fan, seals openings, and mounts the manometer.
• Activation: The fan is turned on before the contractor leaves. The manometer should show offset between the two columns within minutes.
• Post-mitigation test: Within 30 days, 2–7 days of test duration under closed-house conditions.^[3]
• Documentation: System certification, post-mit test result, fan model and warranty, manometer baseline reading.
• Workmanship warranty: 1–2 years typical, 5 years on premium installs.
• Fan warranty: 5 years typical from the manufacturer.

Full warranty and post-install walkthrough →

If the install doesn't bring radon below 4.0 pCi/L, if the system fails within warranty, or if the contractor becomes unreachable:

1. Document the problem in writing to the contractor first. Most issues resolve at this step.
2. File a BBB complaint if the contractor is unresponsive.
3. File a DORA complaint with the Office of Radon Professionals. License revocation is on the table for repeat offenders.^[4]
4. For serious financial harm, consult a Colorado consumer protection attorney.

Full complaint process walkthrough →