How to Choose a Radon Mitigation Contractor

Radon mitigation is a specialized trade. Done correctly, a mitigation system reduces indoor radon levels by 80–99% and operates quietly for years. Done poorly, it can miss entry points, depressurize in the wrong direction, or create new problems. Choosing the right contractor matters—and the selection process is straightforward once you know what to look for.

Start with Certification

Radon contractors can be certified through two primary national programs:

NRPP (National Radon Proficiency Program) — administered by the American Association of Radon Scientists and Technologists (AARST). Widely recognized and respected.

NRSB (National Radon Safety Board) — an independent certification body.

Both require contractors to pass an examination, complete continuing education, and follow a national code of practice. Always verify that a contractor holds a current, active certification from one of these organizations before hiring.

Some states also require licensing for radon work in addition to national certification. Check your state’s requirements—about half of US states regulate radon contractors.

To verify a contractor: Visit the NRPP or NRSB website and search their contractor databases. If a contractor claims certification but doesn’t appear in the database, that’s a serious red flag.

What a Qualified Contractor Does Before Installation

A professional assessment begins before a single hole is drilled. Expect a qualified contractor to:

Conduct or review a radon test. If you haven’t tested yet, the contractor should either conduct a test or accept recent results from a certified lab. Don’t hire someone who insists on installing without a verified elevated reading.

Inspect the foundation and crawl space. The type of mitigation system depends on your foundation type: slab, basement, crawl space, or a combination. A contractor who quotes without seeing your foundation is guessing.

Check for communication. Diagnostic testing confirms that sub-slab air can be moved effectively—a critical factor in system design. A professional uses a simple probe test to verify that suction can be created beneath the slab before deciding how many suction points are needed.

Measure existing radon levels in multiple areas. In large homes or homes with complex foundations, different areas may have different radon entry patterns requiring different mitigation approaches.

Questions to Ask Before Hiring

1. Are you NRPP or NRSB certified? Ask for the certification number and verify it.
2. How many suction points do you recommend for my foundation, and why? The answer should be based on diagnostic testing, not a standard package.
3. Where will the pipe exit the house? Exterior routing through a wall looks different and costs differently than interior routing through closets to the attic.
4. What brand and model fan will you install? Quality matters—ask about the fan’s static pressure rating and whether it’s appropriate for your foundation type.
5. Does the installation include a post-mitigation test? It should. Ask whether they use a short-term test kit or a continuous monitor.
6. What’s the warranty on labor and parts? Reputable contractors warrant both.
7. Are you licensed in this state if required? Know your state’s requirements and verify accordingly.

Red Flags to Avoid

No certification or license. This is the clearest disqualifier.

Same-day install pressure. Legitimate contractors don’t pressure you to commit before they’ve assessed your home.

No diagnostic testing. Installing without checking sub-slab communication is guessing. Some foundations don’t depressurize properly and need alternative approaches.

No post-mitigation test included. You need to verify the system is working. A contractor who doesn’t include this is either cutting costs or not confident in their work.

Unusually low bid. Radon mitigation isn’t a commodity. A bid significantly below competitors usually means fewer suction points, cheaper components, or skipped steps.

Unusually high bid with vague extras. “Premium system” or “deluxe package” descriptions without specific component details are red flags for overcharging.

Understanding the Quote

A detailed quote should specify:

• Number of suction points and their locations
• Pipe diameter and routing path (exterior vs. interior)
• Fan make, model, and specifications
• Whether the quote includes sealing of visible cracks and sump pit covers
• Electrical work (dedicated outlet, if needed)
• Post-mitigation test type and who conducts it
• Warranty terms

What Mitigation Should Cost

For most single-family homes with a single foundation type:

• 1 suction point: $800–$1,500
• 2 suction points: $1,200–$2,000
• 3+ suction points (complex foundations): $1,500–$3,000+

Crawl space sub-membrane systems cost more—typically $1,500–$3,000—because they require installing and sealing a membrane in addition to the depressurization system.

Get at least two or three quotes. The lowest bid isn’t necessarily the best value, but significant discrepancies in price warrant explanation.

After Installation

Confirm the system is running. Fan systems should produce a visible negative pressure reading in the system’s pressure gauge or manometer (the U-tube gauge installed with most systems). If the manometer shows no reading, the fan may not be working.

Conduct the post-installation test. Wait at least 24 hours after installation, then test. If you’re using a short-term kit, follow the instructions carefully. A level at or below 2 pCi/L post-mitigation is a good result.

Annual checks. Verify that the manometer still shows suction annually. If levels seem to rise (new testing shows elevated readings), contact your contractor—fans can fail or ductwork can become blocked.

Frequently Asked Questions

Can I negotiate the price of radon mitigation? Some contractors have flexibility, particularly if multiple suction points are needed and you can be flexible on scheduling. Asking doesn’t hurt.

What if I need mitigation but my home is for sale? Mitigation is typically required before closing when a home tests above 4 pCi/L. Many contractors offer expedited scheduling for real estate transactions.

Can a general contractor install a radon system? Technically, yes in most states. But radon-specific certification ensures the contractor understands sub-slab communication, fan selection, and pressure diagnostics. A general contractor who “can” install radon systems but lacks certification may not do it well.

What happens if the system doesn’t work after installation? A reputable contractor with a warranty will return, diagnose the issue, and fix it at no additional cost. If post-mitigation testing shows levels above 4 pCi/L, insist on remediation under warranty.

For cost information, see our radon mitigation cost guide.

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