Radon mitigation: what to know

What the job involves, what changes the price, and what to ask a pro.

What radon mitigation is

Radon mitigation installs a system to reduce radon levels in a home. The usual system is a vent pipe and fan that draws soil gas from beneath the foundation and releases it above the roof, so it does not enter the living space. Mitigation is specialized work with electrical and roof connections, so it is usually done by a trained contractor, often one certified or licensed by the state.

Signs you need it

  • A radon test came back at a level that a licensed tester or your local health office has called high
  • A follow-up test confirmed a high level after an initial short-term reading
  • You are buying a home with a high radon result, and the buyer or lender wants the level reduced
  • You have a basement, a crawl space or a slab-on-grade home with cracks, sump pits or open penetrations
  • A mitigation system was installed years ago, and the fan has stopped or the gauge shows a change in pressure

What the pro does

  • The contractor reviews the test results and the home's construction, including the foundation type and the basement layout
  • They run diagnostic tests, such as a suction test beneath the slab, to find the best place for the suction point
  • They cut or drill the slab or the foundation for the suction pit, and seal the cracks and openings that draw soil gas
  • They install the vent pipe through the house and the roof, with the fan connected to power by a qualified electrician where the rules call for one
  • They attach a monitor or a gauge so the homeowner can see that the system is running
  • They test the level after installation to confirm the reduction, and provide the documentation of the work

What changes the price

Every job is different, so we do not publish prices. These are the things that move the quote up or down.

  • Foundation type, such as a basement, a crawl space or a slab-on-grade, and the number of suction points needed
  • Pipe routing, including the length of vent pipe, the number of bends and the roof penetration
  • Fan type and its placement, including whether it is inside or outside the home
  • Electrical connection required for the fan and the work by a licensed electrician
  • Sealing of cracks, sump pits and open penetrations to limit the soil gas entry
  • Roof pitch, the height of the vent and the access needed for installation
  • Post-installation testing and the monitor or gauge added to the system

What a written quote should spell out

  • Foundation type and the number of suction points, with their locations
  • Fan model, its placement and the electrical connection, with the licensed electrician named
  • Vent pipe material, size and routing, including the roof penetration and its flashing
  • Sealing work included, such as cracks, sump pits and open penetrations
  • Monitor or gauge included, with how the homeowner will read it
  • Post-installation radon test included, and the result delivered in writing

Questions to ask before you hire

  • Which system will you install, and why is this suction point the right location?
  • How will the pipe be routed, and where does it exit the roof?
  • Who makes the electrical connection for the fan, and is that trade licensed?
  • What sealing will you do, and how will the work affect the rest of the basement?
  • Will you test the level after installation, and will you give me the written result?
  • What is the warranty on the fan, the pipe and the installation?
  • Are you licensed or certified as a radon mitigation contractor in this state?

Red flags

  • They sell a sealant or a paint as the full solution without a suction system
  • They install the fan in a way that puts the exhaust near a window, a door or an air intake
  • They do not test the level after installation, or do not give you the result
  • They will not say who makes the electrical connection or whether it is inspected

What you can do yourself

Do not install a radon mitigation system yourself. The work involves cutting into the foundation, running a pipe through the roof, and connecting a fan to electrical service, and a poorly placed exhaust can draw gas back into the home. You can keep the monitor or gauge readings if a system is already in place, and call the contractor if the reading changes. Ask a licensed contractor to install or service any system.

Licenses and permits

Radon mitigation contractors are commonly required to be licensed or certified by the state, and the electrical connection is often required to be made by a licensed electrician. Check with your state radon or health office and your local building department for the contractor certification and the permit rules that apply to the installation.

Radon mitigation questions

Can I just seal the cracks and fix the radon?

Sealing helps limit soil gas entry, but it is rarely enough by itself. A suction system that draws gas from beneath the foundation is the usual way to lower the level. Ask the contractor what sealing adds and whether a fan is needed.

How long does a mitigation system last?

The fan and the pipe have a service life, and the fan is the part most likely to need replacing. Ask the contractor for the expected life of each part and the warranty terms.

How do I know the system is working?

Look at the gauge or monitor on the pipe. A system that is running shows a steady reading in the expected range. Ask the contractor how the gauge reads when the system is working and what to do if the reading changes.

About this guide

This national guide is written and checked by infinibell. Rules and conditions differ by place, so local pros are credited on guides for the cities they serve, not on national ones.

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