The homeowner’s reference
How to choose a radon mitigation company: 6 checks before you sign
Choose a radon mitigation contractor the way you would for other home repairs, with two extra checks: a current mitigation credential you can verify, and an independent test after the work. EPA says to get more than one estimate and to check references. NRSB recommends estimates from at least two credentialed contractors and notes that the best solution may not be the cheapest.
Sources: EPA: Consumer's Guide to Radon Reduction (2025, PDF); NRSB: Hiring a Radon Professional (2024, PDF); EPA: Home Buyer's and Seller's Guide to Radon (2024, PDF).
1. Verify the mitigation credential
EPA recommends a certified or qualified mitigation contractor trained to fix radon problems, and says to start with your state radon office. Many states require mitigators to be licensed, certified or registered and to install systems that meet state requirements. States that receive EPA indoor radon grants must list only providers credentialed by the state or by NRPP or NRSB.
In states that do not regulate radon work, EPA says to ask whether the contractor holds a proficiency or certification credential and follows industry consensus standards such as ASTM E2121. Check that the credential is current and covers mitigation, not only measurement. NRSB also suggests asking for proof of insurance, bonding and any local licenses or permits the job needs.
Sources: EPA: Consumer's Guide to Radon Reduction (2025, PDF); EPA: Find a Radon Test Kit or Measurement and Mitigation Professional; NRSB: Hiring a Radon Professional (2024, PDF).
2. Expect an inspection and questions about your test
EPA's checklist asks whether the contractor inspected your home's structure before giving an estimate. It also asks whether they reviewed your radon results and checked that proper testing procedures were followed. NRSB asks whether they requested the pre-mitigation test levels and the report. Have the full report ready.
EPA's home-buyer guide says a qualified mitigator should review the testing and decide whether more measurements are needed. Many contractors give free estimates, but they may charge for diagnostic tests. Those tests help choose the system, and they are sometimes necessary for an unfamiliar structure. Ask whether diagnostics are billed separately before the visit.
Sources: EPA: Consumer's Guide to Radon Reduction (2025, PDF); NRSB: Hiring a Radon Professional (2024, PDF); EPA: Home Buyer's and Seller's Guide to Radon (2024, PDF).
3. Ask for evidence from past jobs
EPA suggests asking for references or photographs, plus before-and-after radon results from past work. Contact some of those references and ask whether they were satisfied. NRSB suggests asking how long the contractor has been in the radon business, visiting past projects if you can, and checking online reviews.
Your state radon office, or your county or state consumer protection office, may have information about a contractor. This directory shows credentials, not reviews or the quality of past work.
Sources: EPA: Consumer's Guide to Radon Reduction (2025, PDF); NRSB: Hiring a Radon Professional (2024, PDF).
4. Compare written proposals, not just totals
Get at least two proposals and compare what each one explains: the work involved, how long it will take, and how the system will work. Ask the questions NRSB raises: how the pipes will run through the house, how the finished system will look, how loud it will be, and whether it needs sound-proofing. That list also covers upkeep and running costs, and how the design avoids backdrafting of combustion appliances.
Check that the proposal includes a warning device that alerts you if the system stops working, a connection to the electrical system by a licensed electrician, and a test after installation. EPA notes that a less expensive system may cost more to operate and maintain. The cost guide covers the official price figures and what changes a total.
Sources: NRSB: Hiring a Radon Professional (2024, PDF); EPA: Consumer's Guide to Radon Reduction (2025, PDF).
5. Read the contract before work starts
EPA says to have the contractor prepare a contract before any work starts, and to check that it matches the proposal. The contract should describe the work before and during installation, what the system consists of, and how it will operate. Beyond the price and payment terms, look for the time needed to finish, an agreement to obtain permits and follow building codes, proof of liability insurance and bonding, and responsibility for damage and cleanup.
Read any guarantee closely. EPA says many contractors promise to adjust the system until it reaches a negotiated radon level, such as 2 pCi/L or less. Ask what level is guaranteed and for how long. Ask what the equipment warranty covers, especially the fan, and whether warranties or guarantees transfer if you sell. The contract should also say what the contractor expects you to do before work begins, such as clearing the work area.
Sources: EPA: Consumer's Guide to Radon Reduction (2025, PDF); NRSB: Hiring a Radon Professional (2024, PDF).
6. Plan the test and the paperwork after installation
EPA recommends that an independent, qualified tester do the test after installation. When one firm both tests and mitigates, EPA says there is a potential conflict of interest. Ask who will test, when, and how many tests are planned. EPA's reduction guide says to test no sooner than 24 hours and within 30 days after the system starts running.
Minnesota's health department says systems must be clearly labeled, and that written operating and maintenance instructions and copies of any warranties should be provided. Wherever you live, ask for the labels, the instructions, and the warranty copies, and keep them with the credential number you checked.
Sources: EPA: Home Buyer's and Seller's Guide to Radon (2024, PDF); EPA: Consumer's Guide to Radon Reduction (2025, PDF); Minnesota Department of Health: Radon Mitigation Systems.
Before you sign with a mitigator
- The mitigation credential number, checked against the official source.
- Written proposals from at least two credentialed contractors.
- Did each one inspect the house and review your test report?
- Pipe route, fan location, noise, warning device and electrical work, in writing.
- The guaranteed radon level, for how long, and whether warranties transfer if you sell.
- Who does the independent test after installation, and when.
Find a credentialed provider
Open the mitigation page for your city or county, check each credential number against the linked official source, and ask at least two credentialed mitigators for a written proposal. Use the cost guide to compare the totals.
Find providers in your area · Check credentials by state
Testing instructions and requirements depend on the test, building and jurisdiction. Use the linked agency guidance and your qualified professional’s instructions for your situation.