Radon remediation system

Getting rid of radon in a house means one of two things, EPA's Consumer's Guide explains: some techniques prevent radon from entering your home while others reduce radon levels after it has entered. EPA generally recommends methods that prevent the entry of radon. The table sets out every method the guide describes and what EPA says each one achieves.

So the short answer to what gets rid of radon gas: a soil suction system, installed by a qualified contractor and confirmed with a test. EPA's Citizen's Guide says this system, known as a soil suction radon reduction system, does not require major changes to your home, and that sealing foundation cracks and other openings makes this kind of system more effective and cost-efficient.

Radon gets in because of pressure. EPA's Consumer's Guide says air pressure inside your home is usually lower than pressure in the soil around your home's foundation, and because of this difference in pressure, your home acts like a vacuum, drawing radon in through foundation cracks and other openings. In the United States, it adds, radon gas in soils is the principal source of elevated radon levels in homes.

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1. 1Cracks in solid floors
2. 2Construction joints
3. 3Cracks in walls
4. 4Gaps in suspended floors
5. 5Gaps around service pipes
6. 6Cavities inside walls
7. 7The water supply

A soil suction system reverses that pull. EPA's builder guide, Building Radon Out, states the design goal: to create a vacuum beneath the foundation which is greater in strength than the vacuum applied to the soil by the house itself. With the soil under the slab at lower pressure than the rooms, soil gas moves to the pipe instead of into the house.

In practice, EPA says, one or more suction pipes are inserted through the floor slab into the crushed rock or soil underneath, or below the concrete slab from outside the home. A radon vent fan connected to the suction pipes draws the radon gas from below the home and releases it into the outdoor air while simultaneously creating a negative pressure or vacuum beneath the slab. The number and location of suction pipes depends on how easily air can move in the crushed rock or soil under the slab and on the strength of the radon source. Often, only a single suction point is needed.

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1. 1Soil gas drawn from beneath the slab
2. 2Suction point through the slab
3. 3Vent pipe
4. 4Fan, outside the living space
5. 5Discharge above the roofline

Minnesota's health department describes the finished result: radon mitigation systems use a fan to continuously pull air from the soil and vent it outdoors through a pipe that ends above the edge of the roof, and cracks and openings in the foundation are sealed. What each part does, and how to live with it, is in living with a radon system; the fan has its own guide, radon fans.

EPA says your home type will affect the kind of radon reduction system that will work best. It groups homes by foundation: basement; slab-on-grade, concrete poured at ground level; or crawlspace, a shallow unfinished space under the first floor.

Basement radon remediation and slab homes

In homes that have a basement or a slab-on-grade foundation, EPA says radon is usually reduced by one of four types of soil suction: subslab suction, drain-tile suction, sump-hole suction, or block-wall suction. Some homes have drain tiles or perforated pipe to direct water away from the foundation, and suction on these tiles or pipes is often effective in reducing radon levels. Where a basement has a sump pump, the sump can be capped so that it can continue to drain water and serve as the location for a radon suction pipe. Block-wall suction can be used in basement homes with hollow block foundation walls, and is often used in combination with subslab suction. For a hands-on view, see how to reduce radon in a basement.

How to remediate for radon in a crawl space

An effective method to reduce radon levels in crawlspace homes, EPA says, involves covering the earth floor with a high-density plastic sheet; a vent pipe and fan draw the radon from under the sheet and vent it to the outdoors. This submembrane suction, when properly applied, is the most effective way to reduce radon levels in crawlspace homes. Active crawlspace depressurization, drawing air directly from the crawlspace with a fan, is a less-favorable option: it generally does not work as well, needs special attention to combustion appliance backdrafting, and may raise energy costs. Ventilating the crawlspace passively or with a fan can also lower levels, and in colder climates water pipes, sewer lines and appliances in the crawlspace may need to be insulated against the cold.

Homes with more than one foundation

EPA notes it is common to have a basement under part of the home and a slab-on-grade or crawlspace under the rest. In these situations, a combination of radon reduction techniques may be needed to reduce radon levels to below 4 pCi/L.

WHO reaches the same conclusion from an international view: well-tested, durable and cost-efficient methods exist for preventing radon in new buildings and reducing radon in existing dwellings. No system reaches zero, because about 0.4 pCi/L of radon is normally found in the outside air. Minnesota puts the aim plainly: the goal of the radon mitigation system is to reduce the indoor radon level as low as reasonably achievable.

Remediation follows a confirmed result. EPA's Consumer's Guide recommends fixing your home if the results of one long-term test or the average of two short-term tests show elevated radon levels, at EPA's action level or above. The Citizen's Guide sets out the testing steps that lead there.

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1. 1Step 1: Take a short-term test.

   • Below 4 pCi/LEven if your test result is below 4 pCi/L, you may want to test again sometime in the future.
   • At or above 4 pCi/LIf your result is at or above 4 pCi/L, take a followup test to be sure.

2. 2Step 2: Follow up with either a long-term test or a second short-term test.

   • Long-term testFor a better understanding of your year-round average radon level, take a long-term test.
   • Second short-term testIf you need results quickly, take a second short-term test. If your first short-term test result is more than twice EPA's 4 pCi/L action level, you should take a second short-term test immediately.

3. 3Step 3: Decide whether to fix your home.

   • After a long-term testFix your home if your long-term test result is 4 pCi/L or more.
   • After a second short-term testConsider fixing your home if the average of your first and second test is at or above 4 pCi/L.

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. The Consumer's Guide gives the reason in its own words: any radon exposure has some risk of causing lung cancer, and the lower the radon level in your home, the lower your family's risk of lung cancer. The Citizen's Guide adds that you will reduce your risk of lung cancer when you reduce radon levels, even if you've lived with a radon problem for a long time.

A system is designed for one house. EPA's Consumer's Guide says any information that you may have about the construction of your home could help your contractor choose the best system, and that your contractor will perform a visual inspection of your home and design a system that considers specific features of your home. If that is not enough, the contractor may need to perform diagnostic tests during the initial phase of the installation.

EPA says whether diagnostic tests are needed is decided by details specific to your home, such as the foundation design, what kind of material is under your home, and by the contractor's experience with similar homes and similar radon test results. Ask about cost up front: although many contractors give free estimates, they may charge for diagnostic tests. EPA's 1994 Radon Mitigation Standards also recommend that contractors routinely perform diagnostic tests to evaluate the existence of, or the potential for, backdrafting of natural draft combustion appliances.

EPA recommends that you have a qualified radon mitigation contractor fix your home because lowering high radon levels requires specific technical knowledge and special skills. Its Consumer's Guide warns that without the proper equipment or technical knowledge, you could actually increase your radon level or create other potential hazards and additional costs.

Start with your state radon office. EPA says many states require radon professionals to be licensed, certified or registered, and to install radon mitigation systems that meet state requirements. EPA's professionals page points to one or both of the two privately-run National Radon Proficiency Programs, which the Consumer's Guide names as NRPP and NRSB. In states that don't regulate radon services, EPA says to ask the contractor if they hold a professional proficiency or certification credential, and if they follow industry consensus standards such as ASTM E2121, the Standard Practice for Installing Radon Mitigation Systems in Existing Low-Rise Residential Buildings. Radon411 lists mitigation professionals by state, in an order no one pays for, and your state radon program can say who is credentialed where you live.

Radon mitigation system installers: what to ask

• Will the contractor provide references or photographs, as well as test results of before and after radon levels of past radon reduction work?
• Can the contractor explain what the work will involve, how long it will take to complete, and exactly how the radon reduction system will work?
• Does the proposal include proof of state certification, professional proficiency or certification credentials, and proof of liability insurance and all necessary licenses?
• Does it include diagnostic testing prior to design, a warning device, and testing after installation?
• Does it include a guarantee to reduce radon levels to 4 pCi/L or below, and if so, for how long?

What the contract should say

EPA says to ask the contractor to prepare a contract before any work starts, to read it before you sign, and to make sure everything in the contract matches the original proposal. It should include the total cost of the job, including all taxes and permit fees; the time needed to complete the work; an agreement to obtain necessary permits and follow required building codes; a guarantee that the contractor will be responsible for damage during the job and cleanup after the job; details of any guarantee to reduce radon below a negotiated level; details of hardware warranties; and a declaration stating whether any warranties or guarantees are transferable if you sell your home. EPA notes many contractors provide a guarantee that they will adjust or modify the system to reach a negotiated radon level (e.g., 2 pCi/L or less).

Minnesota's health department publishes a 10 step guide to the radon mitigation process. The steps below follow it, with EPA's detail added where the Consumer's Guide gives it.

1. 1

   A test shows a problem

   Minnesota's step 1: a radon test reveals the home has a radon problem. EPA's fix rule rests on one long-term test or the average of two short-term tests.

2. 2

   Request bids

   Contact licensed radon mitigation professionals to request bids. EPA suggests more than one estimate.

3. 3

   Walk-through

   The professional does a walk-through of the home to lay out how to build the mitigation system; EPA calls this the visual inspection.

4. 4

   Proposal and questions

   Review key questions with the professional and request a proposal, then review bids and select a professional.

5. 5

   Diagnostics

   The professional may perform diagnostic testing to ensure the proper fan size and correct installation.

6. 6

   Sealing

   The professional seals cracks and openings in the basement, which Minnesota says limits the flow of radon and makes the system more efficient.

7. 7

   Installation

   The system is installed. Pennsylvania's radon program says the installation should take less than a day.

8. 8

   Explanation and papers

   The professional provides a full explanation of how the system operates, with written operating and maintenance instructions and copies of any warranties.

9. 9

   Retest

   Retest the home to ensure the system has reduced radon levels, no sooner than 24 hours after the system is running and within 30 days, EPA says.

Pennsylvania adds that after the system has been running for at least 24 hours, the installer should perform a follow-up test to make sure radon levels have been successfully reduced. EPA recommends a separate check as well, covered below under retesting.

EPA's Consumer's Guide gives a list of basic installation requirements that your contractor should meet, and says it is important to verify with your contractor that the radon mitigation standards (ASTM E2121 in particular) are properly met. You also can check with your state radon office to see if there are state requirements that your contractor must meet.

EPA's older 1994 Radon Mitigation Standards set the same expectation from the other side: all radon mitigation systems shall be designed and installed as permanent, integral additions to the building. In Minnesota, you can contact the health department to request a free inspection of your radon mitigation system, if installed after June 2020. The exhaust and fan rules in detail are in the radon fan guide.

EPA does not publish a national price. Its Citizen's Guide says the cost of reducing radon in your home depends on how your home was built and the extent of the radon problem, that most homes can be fixed for about the same cost as other common home repairs, and that the cost to fix can vary widely; consult with your state radon office or get one or more estimates from qualified mitigators. The figures below are published ones, each with its date.

The Consumer's Guide explains the spread: mitigation costs vary due to technique, materials, and the extent of the problem, and your costs may vary depending on the size and design of your home and which radon reduction methods are needed. Minnesota adds that the cost can depend on many factors including the type of radon system to be installed and how your home was built, and that financial assistance may be available depending on household income, geographic location, and funding availability. The mitigation cost page explains what drives the price.

Running costs matter too. EPA says most types of radon reduction systems cause some loss of heated or air conditioned air, which could increase your utility bills, and that systems that use fans are more effective in reducing radon levels; however, they will slightly increase your electric bill. How much your utility bills increase will depend on the climate you live in, what kind of reduction system you select, and how your home is built.

Temporary radon solution before remediation

By opening windows, doors and vents on the lower floors, EPA says, you increase the ventilation in your home, which can result in reduced radon levels. However, once windows, doors and vents are closed, radon concentrations most often return to previous values within about 12 hours. CDC likewise says natural ventilation in any type of house is only a temporary strategy to reduce radon. It can bridge the wait for a contractor, but it is not a fix. See does opening windows reduce radon.

A self-installed radon remediation system is allowed in some places, but EPA's advice is to hire. The Consumer's Guide recommends a qualified contractor, and says that if you decide to do the work yourself, get information on appropriate training courses from your state radon office. The Citizen's Guide says the same: if you are considering fixing your home's radon problem yourself, you should first contact your state radon office for guidance and assistance.

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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.

EPA says the contractor may perform a post-mitigation test to check his work, but recommends you also get an independent follow-up radon measurement, because having an independent tester perform the test, or conducting the measurement yourself, will eliminate any potential conflict of interest. To test the system's effectiveness, a two- to seven-day measurement is recommended. After that, it is a good idea to retest your home at least every two years to be sure radon levels remain low. Keeping a system running is covered in living with a radon system.

Radon gas remediation for well water is a separate job

A soil suction system treats radon from the ground. EPA says that compared to radon entering your home through water, radon entering your home through soil is usually a much larger risk, and that if you have a private well you should consider testing for radon in both air and water. Point-of-entry treatment for the whole home, usually granular activated carbon filters or aeration systems, can effectively remove radon from the water before it enters your home's water distribution system. Point-of-use devices at the tap are not effective in reducing the risk from breathing radon released into the air from all water used in the home. See radon in water.