How to Choose a Radon Mitigation Contractor: 8 Questions to Ask

Picking a radon contractor shouldn't feel like a gamble. But if you don't know what to ask, it kind of is.

Here are 8 questions that separate the pros from the guys with a truck and a drill. Print this list. Bring it to every estimate.

1. Are You Currently NRPP or NRSB Certified?

This is the non-negotiable. The National Radon Proficiency Program (NRPP) and National Radon Safety Board (NRSB) are the two nationally recognized credentialing bodies. Certification means they passed an exam, complete continuing education, and follow professional standards.

Ask to see the card. Or look them up yourself -- both organizations maintain online directories. And yeah, some states require additional state-level licensing. Pennsylvania, New Jersey, and Illinois all have their own requirements on top of national certification.

2. Is a Post-Mitigation Test Included?

Now, this is where it gets interesting. The post-test is the ONLY way to confirm the system works. Some contractors include it. Others charge $100 to $200 extra.

Here's what nobody tells you: ideally, the post-test should be done by a different company than the one that installed the system. Conflict of interest and all that. At minimum, the contractor should coordinate the test and guarantee results below 4.0 pCi/L.

3. What Type of System Do You Recommend?

A knowledgeable contractor should explain their recommendation based on YOUR foundation. Basement or slab? Sub-slab depressurization. Crawlspace? Sub-membrane suction. We broke down the differences between SSD and SMD in detail if you want the technical rundown.

If someone can't explain why they're recommending a specific approach for your home, that's a red flag.

4. How Many Suction Points?

Most homes need one or two. The number depends on foundation size, soil conditions, and whether there are separate slab sections.

The important question isn't "how many" -- it's "how did you decide?" A contractor who walks your foundation, checks for separate pours, and talks about soil permeability? That's someone who knows what they're doing. Someone who quotes a number without looking at the house? Not so much.

5. What Warranty Do You Provide?

Reputable contractors offer warranties on both parts and labor. Typical terms: 1 to 5 years on the fan, lifetime on the piping. Some go further with a radon-level guarantee -- they'll make modifications at no charge if levels stay above 4.0 after installation.

Get it in writing. Before work starts. Not after.

6. Do You Carry Liability Insurance?

General liability and workers' comp. Both required. This protects you if the install causes property damage or if someone gets hurt on your property. Ask for a certificate of insurance and make sure it's current.

Quick reality check: if a contractor hesitates or dodges this question, walk away.

7. What's Your Timeline?

Standard installs take 4 to 8 hours. One day, in and out. But scheduling varies. During spring and summer, contractors in high-radon areas like the Denver metro or Boston area can be booked 2 to 3 weeks out.

If you're in a real estate transaction with a closing deadline, say so upfront. Experienced contractors know how to prioritize these jobs.

8. Can You Provide References?

Two or three recent installs in your area. Same foundation type as yours, ideally. A contractor who's done hundreds of systems shouldn't have any trouble with this.

When you follow up with references, ask one thing: did the post-mitigation test come back below 4.0? That's the only number that matters.

Comparing Quotes: Price Isn't Everything

Get three quotes minimum. But don't just compare the bottom line. Compare what's included: number of suction points, fan quality and warranty, sealing scope, post-test inclusion, labor warranty.

The cheapest quote isn't always the best deal. And the most expensive one isn't always the best work. Look at the scope, not the price. That's how you avoid getting burned.