How to Hire a Certified Radon Contractor

NRPP and NRSB: What These Certifications Mean

Two national bodies certify radon professionals in the United States. Both are recognized by the EPA and state radon programs. Either certification is acceptable unless your state specifically requires one over the other.

NRPP — National Radon Proficiency Program

Administered by the American Association of Radon Scientists and Technologists (AARST). The NRPP is the larger of the two programs and covers both radon measurement professionals and radon mitigation professionals. To earn NRPP certification, an individual must pass a written examination, demonstrate knowledge of AARST ANSI installation standards, and maintain continuing education for renewal every two years. Search certified professionals at nrpp.info.

NRSB — National Radon Safety Board

An independent certification organization offering certification for both measurement and mitigation. NRSB certification requires examination, practical training requirements, and biennial renewal. Search at nrsb.org.

When asking a contractor about their certification, get the specific certification number and expiration date — then verify it takes under a minute at either database. Do not accept "we're certified" without seeing the actual certificate or looking it up yourself.

How to Verify a Contractor's Certification in 60 Seconds

1. Go to nrpp.info → click "Find a Certified Professional" → enter the contractor's name or your ZIP code.
2. Alternatively, go to nrsb.org → click "Find Certified Professional."
3. Confirm: the name matches exactly, the certification type is "mitigation" (not measurement only), and the expiration date has not passed.
4. For states with their own licensing programs (IL, MN, CO, PA, NJ, VA, MD, IA, CT), also check the state agency database. Links are in each state guide.

States That Require Specific Certification

10 Questions to Ask Before Hiring

1. "Can you provide your NRPP or NRSB certificate number so I can verify it?" Any reputable contractor answers this without hesitation.
2. "What type of system will you install — sub-slab depressurization, crawl space membrane, or combination?" The answer should match your foundation type. SSD for basement/slab; encapsulation + suction for crawl space.
3. "How many suction points do you plan to install, and how do you determine that?" A professional should perform a diagnostic (pressure field extension test) before finalizing the design — not just guess.
4. "What fan model will you use and what is its warranty?" Most quality fans (RadonAway, Festa) carry 5-year manufacturer warranties. You should know what's being installed.
5. "Will you pull any required electrical permits?" Correct answer: yes, if new wiring is needed. Anything else is a red flag.
6. "Does your quote include a post-mitigation radon test?" It should. Some contractors include it; others charge separately. Know before signing.
7. "Do you offer a performance guarantee — what happens if post-test results are still above 4 pCi/L?" Many certified contractors guarantee sub-4 pCi/L results and will return to adjust at no charge.
8. "Where will the exhaust terminate?" Must be above the roofline or at least 12 inches above any window or door. Side-wall venting is acceptable if clearances are met — but garage venting is never acceptable.
9. "What will the system label include?" AARST standards require a label with installation date, contractor name, and certification number. If they don't know what a system label is, that's a red flag.
10. "Can you provide references from the past 6 months?" Recent references are more meaningful than older ones for assessing current work quality.

What a Complete Quote Should Include

• Specific system type (SSD, sub-membrane, combination)
• Number of suction points planned and rationale
• Fan make, model, and CFM specification
• Pipe routing description (interior vs. exterior, discharge location)
• Visual warning device (manometer or U-tube) included
• System labeling per AARST standards
• Permit handling — which permits will be pulled and by whom
• Post-mitigation test — included or separate charge
• Performance guarantee terms
• Fan warranty period
• Total price, all-in, with no surprise fees

Red Flags That Signal an Unqualified Contractor

• Refuses to provide certification number or is vague about which body certified them
• Does not perform any diagnostic testing before finalizing system design
• Quotes a price over the phone without seeing the foundation
• Cannot explain where exhaust will terminate or doesn't mention clearance requirements
• Says "no permit is ever needed" without checking your specific address
• Does not include a post-mitigation test in the scope or mention it at all
• Requires full payment upfront before work begins (small deposit is normal; full payment is not)
• Significantly lower price than all other quotes with no clear explanation why
• Pressures you to sign same day or claims a "one-day deal"

FAQ