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Radon mitigation companies

How to choose a radon mitigation contractor, what the proposal and contract should include, what happens on installation day and after, and the companies listed by state.

Updated October 2, 2026

Short answer

What a radon mitigation contractor does

Hire one your state licenses, where it licenses them, or one certified by NRPP or NRSB where it does not, and get more than one estimate.

Lowering a high radon level takes specific technical knowledge and special skills: without the right equipment and knowledge, a do-it-yourself attempt can actually raise the level or create other hazards and costs.

A qualified mitigation contractor should be able to:

  • Review your test results and say whether more measurements are needed
  • Evaluate the problem and give you a detailed, written proposal
  • Design a radon reduction system for your home
  • Install it to EPA's recommended standard, or to state and local codes
  • Make sure the finished system lowers radon to acceptable levels

The contractor inspects your home and designs around its features, and may run diagnostic tests early in the installation to choose where the system goes and how big the fan should be.

Sub-slab depressurization system in a house cross-sectionGround levelLiving spaceBasement12345
  1. Soil gas drawn from beneath the slab
  2. Suction point through the slab
  3. Vent pipe
  4. Fan, outside the living space
  5. Discharge above the roofline
A sub-slab depressurization system, the most common kind a contractor installs.

When to call

When you need one

Test first if you have no result: EPA recommends the contractor review your measurement results before any work starts.

  • A high result

    4 pCi/L or more

    EPA recommends fixing a home when the radon level is 4 pCi/L or higher. EPA recommends considering a fix when the level is between 2 and 4 pCi/L.

  • A system that stopped

    The warning device says so

    If an existing system's warning device shows it is not working properly, call a contractor to have it checked.

  • A passive system

    A new home that tests high

    Where a passive system's test is 4 pCi/L or more, a qualified mitigator can estimate the cost of adding a vent fan to make it active.

No result yet? Find a tester or choose a test kit.

The directory

Mitigation companies by state

316 businesses are listed for mitigation. Choose a state for its own licensing rule and its list.

Only states with listings of their own are in the table. Every state has its own page, with its licensing rule: choose it on the map or in the search above.

316 professionals listed. Showing 1 to 1224.

On this page: 7 testing and mitigation, 517 mitigation

Testing and mitigation (7)

Mitigation (517)

Show 12 more on this page

Credentials

Licensing and certification for mitigators

Your state's rules come first. Where it has none, national certification is the credential to ask for.

Your state's rules
Many states require radon professionals to be licensed, certified or registered, and to install systems that meet state requirements. A system in your home must conform to your state's regulations; where there are none, EPA recommends its most current voluntary consensus-based standards.
NRPP and NRSB
NRPP certifies Mitigation Specialists. NRSB certifies Radon Mitigation Specialists, who must be able to weigh alternative mitigation strategies and design and install effective systems, and who must hold a valid state license to work in a state that requires one.
The standard for existing homes
ANSI/AARST SGM-SF-2023, Soil Gas Mitigation Standards for Existing Homes, sets practices and minimum requirements for keeping soil gas out of existing homes, and can be viewed for free.

  • 14

    Say they license or certify radon professionals

    The state's own radon program page says the state licenses, certifies or registers people who test or mitigate.

    California, Colorado, Florida, Illinois, Indiana, Iowa, Maine, Minnesota, Nebraska, New Jersey, Ohio, Pennsylvania, Rhode Island, West Virginia

  • 9

    Say they do not

    The state's own page says it does not license or certify radon professionals. National certification is then the credential to ask for.

    Connecticut, Georgia, Michigan, Montana, New Hampshire, New Mexico, New York, Texas, Wisconsin

  • 2

    Say something else

    The page speaks to credentials without a yes or no: a rule that names the national programs, or a program still being written.

    North Carolina, Virginia

The other 26 program pages (of 50 states and the District of Columbia) do not state a rule, or have not been read yet. Read from each state's own radon program page, checked on September 25, 2026. Each state's page here quotes its program's own sentence; choose yours on the map above or on the state radon programs page.

Ten steps

How to choose a mitigation contractor

From the test to the retest, as Minnesota's Department of Health lays the process out.

  1. Test

    A radon test shows the home has a radon problem.

  2. Ask for bids

    Contact licensed mitigation professionals and request bids.

  3. Walk-through

    Each professional walks through the home to lay out the system.

  4. Proposal

    Go through your questions with each and ask for a proposal.

  5. Choose

    Review the bids and select a professional.

  6. Diagnostics

    The professional may test to get the fan size and installation right.

  7. Sealing

    The professional seals cracks and openings in the basement.

  8. Installation

    The professional installs the radon mitigation system.

  9. Hand-over

    The professional explains fully how the system operates.

  10. Retest

    Retest to make sure the system has reduced radon levels.

Questions to ask each contractor

Choose a contractor the way you would for any other home repair: get more than one estimate, ask for references and contact some of them. Your state radon office or a consumer protection office can tell you about a contractor too.

  • Will you provide references or photographs, and before and after test results from past radon work?
  • Can you explain what the work involves, how long it will take, and exactly how the system will work?
  • Do you charge for diagnostic tests? Many contractors give free estimates but may charge for these.
  • Did you inspect the home's structure before giving the estimate?
  • Did you review the quality of my test results, and whether the right procedures were followed?
  • Which state license or national certification do you hold, and can I see the ID card?

On paper

What the proposal and the contract should include

The proposal

  • Proof of state certification, or of a proficiency or certification credential
  • Proof of liability insurance, of being bonded, and of every license local rules require
  • Diagnostic testing before the system is designed and installed
  • A warning device that tells you if the system stops working
  • Testing after installation to make sure the system works
  • A guarantee to reduce radon to 4 pCi/L or below, and for how long

Compare what you get for the money, not only the price: a less expensive system may cost more to run and maintain and may look less tidy, and the quality of the materials affects how long it lasts.

The contract

Ask for a contract before any work starts, read it before you sign, and make sure it matches the proposal. It should describe the work before and during installation, what the system consists of and how it will operate, and include:

  • The total cost with all taxes and permit fees, any deposit, and when payment is due
  • The time needed to complete the work
  • An agreement to obtain the necessary permits and follow building codes
  • Responsibility for damage during the job and cleanup after it
  • Details of any guarantee to reduce radon below a negotiated level
  • Whether warranties or guarantees transfer if you sell the home
  • What you need to do before work begins, such as clearing the work area

Many contractors guarantee to adjust or modify the system to reach a negotiated level, such as 2 pCi/L or less. Typical options include an extended warranty, a service plan or improved looks.

What you should get

Installation day and after

A finished system is labelled, has a warning device, comes with written instructions, and is tested.

  • A clear label on the system, so nobody changes it by accident
  • A warning device that alerts you if the system stops working properly
  • A full explanation of how the system works and how to maintain it
  • Written operating and maintenance instructions and copies of any warranties
  • In Minnesota, a system tag with the installer's name, phone number, install date and license number
  • A test no sooner than 24 hours after the system is running, and within 30 days

An independent tester, or a test you run yourself, removes any conflict of interest in that first test: EPA recommends an independent, qualified tester when the same firm would otherwise test and install, and some states may require the homeowner to sign a waiver in that case. Find a tester.

  1. Day of installation

    The system goes in

    Keep the fan running at all times: it must run continuously for the system to work correctly.

  2. No sooner than 24 hours

    Earliest post-mitigation test

    Test no sooner than 24 hours after your system is in operation with the fan on, if it has one.

  3. Within 30 days

    Post-mitigation test done

    A two- to seven-day measurement is recommended, and EPA recommends an independent follow-up radon measurement as well as any test the contractor runs.

  4. At least every two years

    Retest

    Retest your home at least every two years to be sure radon levels remain low.

Test conditions: Windows and doors must be closed 12 hours before and during the test, except for normal entry and exit. Not drawn to scale.

After a remodel. After you remodel, retest in the lowest lived-in area to make sure the construction did not reduce the effectiveness of the radon reduction system.

After installation: the fan runs continuously, a test within 30 days, then at least every two years.

Upkeep

Repair, maintenance and cost

Keeping it running

Fans may last five years or more, and manufacturer warranties tend not to exceed five years; after that a fan may need repair or replacement. A U-tube manometer shows whether the fan is working, and an active notification monitor alarms when it is not.

A system with a fan lowers radon more effectively and slightly raises the electric bill. Retest at least every two years. How the radon fan works.

What it costs

EPA says most homes can be fixed for about the same cost as other common home repairs. Many contractors give free estimates but may charge for diagnostic tests, so ask before the visit.

Every published figure, with its publisher and year, is on what radon mitigation costs.

Before you sign

Check a mitigator's credential

  1. Your state's own list

    Start with your state's radon program. Licensing is done by the state, and most states can give you a list of radon service providers working there.

  2. NRPP's search

    The National Radon Proficiency Program's search finds its Certified Mitigation Specialists and Certified Measurement Professionals by area, by name, or by the 6-digit NRPP ID number a professional can give you.

  3. NRSB's search

    The National Radon Safety Board's search finds a professional in your area, or confirms that a named professional is NRSB certified.

  4. The ID card

    The programs usually issue a photo ID card showing the holder's qualifications and its expiry date. Ask to see it, and if in doubt, check with the body that issued it.

Trust

How these listings are verified

No company pays to be listed, labelled or placed higher.

  • Listed by state registry

    This business appears on a state's published list of licensed radon professionals, which Radon411 read directly from the state's own site. The business has not confirmed these details itself.

  • Claimed profile

    The business confirmed these details itself. Radon411 has not independently checked them against an official record.

  • Business information verified

    Radon411 checked this business's details against an official record, such as a state contractor registry. This is a business status. It does not mean any specific certification has been verified, see each certification below for that.

  • Certification verified

    Radon411 retrieved this credential directly from the issuing body's own record and confirmed it matches this business.

  • Not yet verified

    The business, or a list it was imported from, reports this credential. Radon411 has not checked it against the issuing body's own record, so treat it as self-reported until it is.

  • Unverified

    This business's information was imported from a public source and has not yet been checked by Radon411 or confirmed by the business itself.

Three rules that never change

No one pays for a label. A label comes from where a listing was read or what was checked against the issuing body's own record. Approving a business's claim on its own listing can never mark a credential as verified.

No one pays for a place in the order. Lists are ordered by how much has been checked, then by name. A paid listing tier is not an input to the order at all.

No leads are sold. There is no quote form here. You contact a business directly, by its own website or phone number, and Radon411 never passes your details to anyone.

Run a radon business? Claim your listing to correct its details, or ask to be added.

Questions

Common questions

How do I choose a radon mitigation company?

Start with your state's licensing rule, then get bids from more than one licensed or certified contractor, check references, and compare written proposals on what they include, not only on price.

Why work with a certified mitigator?

Lowering a high radon level takes specific technical knowledge and special skills. Without them, you could raise the level or create other hazards and costs.

How do I check a mitigator's license?

Use your state's own list where it publishes one, and NRPP's or NRSB's search for a national certification. Ask to see the photo ID card the programs usually issue.

Does the installer test the system afterward?

A good proposal includes a test after installation, but EPA recommends an independent, qualified tester, or your own test, to avoid a conflict of interest.

How many estimates should I get?

More than one. Minnesota's steps start with bids from several licensed professionals.

Who repairs a radon fan?

A mitigation contractor. Fans may last five years or more and then need repair or replacement.

What guarantee should I ask for?

A guarantee to reduce radon to a negotiated level, and for how long. Many contractors guarantee to adjust the system to reach a level such as 2 pCi/L or less.

Can a company pay to be listed first here?

No. The order is by how much has been checked, then by name, and no label can be bought.

Next steps

Where to go next