Radon Gas Remediation & Remedies
“Radon is a health hazard, why move in with it, if the gas does not kill you it would most certainly have an adverse affect on your families health, evict the gas.”
High Radon Levels Can be Reduced
EPA recommends that you take action to reduce your home’s indoor radon levels if your radon test result is 4 pCi/L or higher. It is better to correct a radon problem before placing your home on the market because then you have more time to address a radon problem.
If elevated levels are found during the real estate transaction, the buyer and seller should discuss the timing and costs of the radon reduction. The cost of making repairs to reduce radon levels depends on how your home was built and other factors. Most homes can be fixed for about the same cost as other common home repairs. Check with and get an estimate from one or more qualified mitigation experts.
How To Lower The Radon Level In Your Home
A variety of methods can be used to reduce radon in homes. Sealing cracks and other openings in the foundation is a basic part of most approaches to radon reduction. EPA does not recommend the use of sealing alone to limit radon entry. Sealing alone has not been shown to lower radon levels significantly or consistently.
In most cases, a system with a vent pipe(s) and fan(s) is used to reduce radon. These “sub-slab depressurization” systems do not require major changes to your home. Similar systems can also be installed in homes with crawl space. These systems prevent radon gas from entering the home from below the concrete floor and from outside the foundation. Radon mitigation contractors may use other methods that may also work in your home. The right system depends on the design of your home and other factors.
Radon Reduction Techniques
There are several methods a contractor can use to lower radon levels in your home. Some techniques prevent radon from entering your home while others reduce radon levels after it has entered. EPA generally recommends methods which prevent the entry of radon. Soil suction, for example, prevents radon from entering your home by drawing the radon from below the home and venting
it through a pipe, or pipes, to the air above the home where it is quickly diluted.
Any information that you may have about the construction of your home could help your contractor choose the best system. Your contractor will perform a visual inspection of your home and design a system that considers specific features of your home. If this inspection fails to provide enough information, the contractor will need to perform diagnostic tests during the initial phase of the installation to help develop the best radon reduction system for your home. For instance, your contractor can use chemical smoke to find the source and direction of air movement. A contractor can learn air flow sources and directions by watching a small amount of smoke that he or she shot into holes, drains, sumps, or along cracks. The sources of air flow show possible radon routes. A contractor may have concerns about back drafting of combustion appliances when considering radon mitigation options, and may recommend that the homeowner have the appliances checked by a qualified inspector.
Another type of diagnostic test is a soil communication test. This test uses a vacuum cleaner and chemical smoke to determine how easily air can move from one point to another under the foundation. By inserting a vacuum cleaner hose in one small hole and using chemical smoke in a second small hole, a contractor can see if the smoke is pulled down into the second hole by the force of the vacuum cleaner’s suction. Watching the smoke during a soil communication test helps a contractor decide if certain radon reduction systems would work well in your home.
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.
Diagnostic tests photos
Locating high levels of gas entry points.
Radon enters from a variety of places, testing helps determine type and location of mitigation system.
Home Foundation Types
Your home type will affect the kind of radon reduction system that will work best. Homes are generally categorized according to their foundation design. For example: basement, slab-on-grade, concrete poured at ground level; or crawlspace, a shallow unfinished space under the first floor. Some homes have more than one foundation design feature. For instance, it is common to have a basement under part of the home and to have a slab-on-grade or crawlspace under the rest of the home. In these situations a combination of radon reduction techniques may be needed to reduce radon levels to below 4 pCi/L.
Radon reduction systems can be grouped by home foundation design. Find your type of foundation design above and read about which radon reduction systems may be best for your home.
Basement and Slab-on-Grade Home In homes that have a basement or a slab-on-grade foundation, radon is usually reduced by one of four types of soil suction: sub-slab suction, drain-tile suction, sump-hole suction, or block-wall suction.
Active Sub-slab suction — also called sub-slab depressurization — is the most common and usually the most reliable radon reduction method. One or more suction pipes are inserted through the floor slab into the crushed rock or soil underneath. They also may be inserted below the concrete slab from outside the home. The number and location of suction pipes that are needed 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.
A contractor usually gets this information from visual inspection, from diagnostic tests, and/or from experience. 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. Common fan locations include unconditioned home and garage spaces, including attics, and the exterior of the home.
Passive sub-slab suction is the same as active sub-slab suction except it relies on natural pressure differentials and air currents instead of a fan to draw radon up from below the home. Passive sub-slab suction is usually associated with radon-resistant features installed in newly constructed homes. Passive sub-slab suction is generally not as effective in reducing high radon levels as active sub-slab suction.
Some homes have drain tiles or perforated pipe to direct water away from the foundation of the home. Suction on these tiles or pipes are often effective in reducing radon levels.
One variation of sub-slab and drain tile suction is sump-hole suction. Often, when a home with a basement has a sump pump to remove unwanted water, 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. This method removes radon and depressurizes the block wall, similar to sub-slab suction. This method is often used in combination with sub-slab suction.
An effective method to reduce radon levels in crawlspace homes involves covering the earth floor with a high-density plastic sheet. A vent pipe and fan are used to draw the radon from under the sheet and vent it to the outdoors. This form of soil suction is called sub-membrane suction, and when properly applied is the most effective way to reduce radon levels in crawlspace homes. Another less-favorable option is active crawlspace depressurization which involves drawing air directly from the crawlspace using a fan. This technique generally does not work as well as sub-membrane suction and requires special attention to combustion appliance back-drafting and sealing the crawlspace from other portions of the home, and may also result in increased energy costs due to loss of conditioned air from the home.
In some cases, radon levels can be lowered by ventilating the crawlspace passively, without the use of a fan, or actively, with the use of a fan. Crawlspace ventilation may lower indoor radon levels both by reducing the home’s suction on the soil and by diluting the radon beneath the home. Passive ventilation in a crawlspace is achieved by opening vents, or installing additional vents. Active ventilation uses a fan to blow air through the crawlspace instead of relying on natural air circulation. In colder climates, for either passive or active crawlspace ventilation, water pipes, sewer lines and appliances in the crawlspace may need to be insulated against the cold. These ventilation options could result in increased energy costs for the home.
Other Types of Radon Reduction Methods
Other radon reduction techniques that can be used in any type of home include: sealing, home or room pressurization, heat recovery ventilation and natural ventilation.
Sealing cracks and other openings in the foundation is a basic part of most approaches to radon reduction. Sealing the cracks limits the flow of radon into your home, thereby making other radon reduction techniques more effective and cost-efficient. It also reduces the loss of conditioned air. EPA does not recommend the use of sealing alone to reduce radon because, by itself, sealing has not been shown to lower radon levels significantly or consistently. It is difficult to identify and permanently seal the places where radon is entering. Normal settling of your home opens new entry routes and reopens old ones.
Home or room pressurization uses a fan to blow air into the basement, or living area from either upstairs or outdoors. It attempts to create enough pressure at the lowest level indoors — in a basement, for example — to prevent radon from entering into the home. The effectiveness of this technique is limited by home construction, climate, and other appliances in the home and occupant lifestyle. In order to maintain enough pressure to keep radon out, the doors and windows at the lowest level must not be left opened, except for normal entry and exit. This approach generally results in more outdoor air being introduced into the home, which can cause moisture intrusion and energy penalties. Consequently, this technique should only be considered after the other, more-common techniques have not sufficiently reduced radon.
Positive pressure fan
A heat recovery ventilator, or HRV, also called an air-to-air heat exchanger, can be installed to increase ventilation which will help reduce the radon levels in your home. An HRV will increase ventilation by introducing outdoor air while using the heated or cooled air being exhausted to warm or cool the incoming air. HRVs can be designed to ventilate all or part of your home, although they are more effective in reducing radon levels when used to ventilate only the basement. If properly balanced and maintained, they ensure a constant degree of ventilation throughout the year. HRVs also can improve air quality in homes that have other indoor pollutants. There could be significant increase in the heating and cooling costs with an HRV, but not as great as ventilation without heat recovery (see the installation and operating cost table).
Some natural ventilation occurs in all homes. By opening windows, doors, and vents on the lower floors you increase the ventilation in your home. This increase in ventilation mixes outdoor air with the indoor air containing radon, and 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. Natural ventilation in any type of home should normally be regarded as only a temporary radon reduction approach because of the following disadvantages: loss of conditioned air and related discomfort; greatly increased costs of conditioning additional outside air; and security concerns.
Radon in Water
Most often, the radon in your home’s indoor air can come from two sources, the soil or your water supply. Compared to radon entering your home through water, radon entering your home through soil is usually a much larger risk. If you are concerned about radon and you have a private well, consider testing for radon in both air and water. By testing for radon in both air and water, the results could enable you to more completely assess the radon mitigation options best suited to your situation. The devices and procedures for testing your home’s water supply are different from those used for measuring radon in air.
The radon in your water supply poses an inhalation risk and a small ingestion risk. Most of your risk from radon in water comes from radon released into the air when water is used for showering and other household purposes. Research has shown that your risk of lung cancer from breathing radon in air is much larger than your risk of stomach cancer from swallowing water with radon in it.
Radon in your home’s water is not usually a problem when its source is surface water. A radon in water problem is more likely when its source is ground water, such as a private well or a public water supply system that uses ground water. Some public water systems treat their water to reduce radon levels before it is delivered to your home. If you are concerned that radon may be entering your home through the water and your water comes from a public water supply, contact your water supplier.
If you’ve tested your private well and have a radon in water problem, it can be easily fixed. Your home’s water supply can be treated in one of two ways. Point-of-entry treatment for the whole home can effectively remove radon from the water before it enters your home’s water distribution system. Point-of-entry treatment usually employs either granular activated carbon, or GAC, filters or aeration systems. While GAC filters usually cost less than aeration systems, filters can collect radioactivity and may require a special method of disposal. Both GAC filters and aeration systems have advantages and disadvantages that should be discussed with your state radon office or a water treatment professional. Point-of-use treatment devices remove radon from your water at the tap, but only treat a small portion of the water you use, such as the water you drink. Point-of-use devices are not effective in reducing the risk from breathing radon released into the air from all water used in the home.
Installation and Operating Cost Table
|Technique||Typical Radon Reduction||Typical Range of Installation Costs (Contractor)||Typical Operating Cost Range
for Fan Electricity & Heated/Cooled
Air Loss (Annual)
|Subslab Suction (Subslab Depressurization)||50% to 90%||$800 to $3,500||$50 to $200||Works best if air can move easily in material under slab.|
|Passive Subslab Suction||30% to 70%||$550 to $2,750||There may be some energy penalties||May be more effective in cold climates; not as effective as active subslab suction.|
|Draintile Suction||50% to 99%||$800 to $2,300||$50 to $200||Can work with either partial or complete drain tile loops.|
|Block-Wall Suction||50% to 99%||$1,500 to $3,500||$100 to $400||Only in homes with hollow block-walls; requires sealing of major openings.|
|Sump-Hole Suction||50% to 99%||$800 to $3,000||$50 to $250||Works best if air moves easily to sump from under the slab.|
|Submembrane Depressurization in a Crawlspace.||50% to 99%||$1,000 to $3,000||$50 to $250||Less heat loss than natural ventilation in cold winter climates.|
|Natural Ventilation in a Crawlspace||0% to 50%||None $200 to $700 if additional vents installed||There may be some energy penalties.||Costs variable.|
|Sealing of Radon Entry Routes||See Comments||$100 to $2,000||None||Normally only used with other techniques; proper materials and installation required.|
|Home (Basement) Pressurization||50% to 99%||None $200 to $700 if additional vents installed||$150 to $500||Significant heated or cooled air loss; operating costs depend on utility rates and amount of ventilation|
|Natural Ventilation||Variable/Temporary||None $200 to $700 if additional vents installed||$100 to $700||Significant heated or cooled air loss; operating costs depend on utility rates and amount of ventilation.|
|Heat Recovery Ventilation of HRV||Variable/ See Comments||$1,200 to $3,500||$75 to $500 for continuous operation||Limited use; effectiveness limited by radon concentration and the amount of ventilation air available for dilution by the HRV. Best applied to Limited-space areas like basements.|
|Private Well Water Systems; Aeration||95% to 99%||$3,000 to $5,000||$50 to $150||Generally more efficient that GAC; requires annual cleaning to maintain effectiveness and to prevent contamination; requires venting radon to outdoors.|
|Private Well Water Systems; Granular Activated Carbon, or GAC||85% to 99%||$1,000 to $3,500||None||Less efficient for higher levels than aeration; use for moderate levels, around 5,000 pCi/L or less in water; radioactive radon by-products can build on carbon; may need radiation shield around tanks and care in disposal.|
1. The fan electricity and home heating/cooling loss cost range is based on certain assumptions regarding climate, your home’s size, and the cost of electricity and fuel. Your costs may vary.
2. Costs for cosmetic treatments to the home may increase the typical installation costs shown above.
Radon and Home Renovations
If you are planning any major renovations, such as converting an unfinished basement area into living space, it is especially important to test the area for radon before you begin.
If your test results indicate an elevated radon level, radon-resistant techniques can be inexpensively included as part of the renovation. Major renovations can change the level of radon in any home. Test again after the work is completed.
You should also test your home again after it is fixed to be sure that radon levels have been reduced. If your living patterns change and you begin occupying a lower level of your home (such as a basement) you should retest your home on that level. In addition, it is a good idea to retest your home sometime in the future to be sure radon levels remain low.
Remodeling Your Home After Radon Levels Have Been Lowered
If you decide to make major structural changes to your home after you have had a radon reduction system installed, such as converting an unfinished basement area into living space, ask your radon contractor whether these changes could void any warranties. If you are planning to add a new foundation for an addition to your home, ask your radon contractor about what measures should be taken to ensure reduced radon levels throughout the home. 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.
Checking Your Contractor’s Work
Below is a list of basic installation requirements that your contractor should meet when installing a radon reduction system in your home. It is important to verify with your contractor that the radon mitigation standards are properly met to ensure that your radon reduction system will be effective. You can also check with your state radon office to see if there are state requirements that your contractor must meet.
- Radon reduction systems must be clearly labeled. This will avoid accidental changes to the system that could disrupt its function.
- The exhaust pipes of soil suction systems must vent above the surface of the roof and 10 feet or more above the ground, and must be at least 10 feet away from windows, doors, or other openings that could allow the radon to reenter the home, if the exhaust pipes do not vent at least 2 feet above these openings.
- The exhaust fan must not be located in or below a livable area. For instance, it should be in an unoccupied attic of the home or outside — not in a basement.
- If installing an exhaust fan outside, the contractor must install a fan that meets local building codes for exterior use.
- Electrical connections of all active radon reduction systems must be installed according to local electrical codes.
- A warning device must be installed to alert you if an active system stops working properly. Examples of system failure warning devices are: a liquid gauge, a sound alarm, a light indicator, and a dial, or needle display, gauge. The warning device must be placed where it can be seen or heard easily. Your contractor should check that the warning device works. Later on, if your monitor shows that the system is not working properly, call a contractor to have it checked.
- A post-mitigation radon test should be done within 30 days of system installation, but no sooner than 24 hours after your system is in operation with the fan on, if it has one. The contractor may perform a post-mitigation test to check his work and the initial effectiveness of the system; however, it is recommended that you also get an independent follow-up radon measurement. 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. Test conditions: windows and doors must be closed 12 hours before and during the test, except for normal entry and exit.
- Make sure your contractor completely explains your radon reduction system, demonstrates how it operates and explains how to maintain it. Ask for written operating and maintenance instructions and copies of any warranties.