There is no "safe level" of this radioactive gas in homes – you should always strive to reduce its concentration to a minimum. The US EPA recommends that you should mitigate if your radon test reads 4 pCi/L or higher, and consider radon mitigation if the radon level is above 2 pCi/L. There are a few radon reduction methods available:
|Comparison of Radon Remediation Methods|
|Method||Typical Radon Reduction||Typical installation costs (contractor)||Typical operating costs for fan electricity and in energy losses in heated/cooled air (annual)||Comments|
|Fan-based subslab suction (Active Subslab Depressurization)||50%-99%||EPA:
|$225-500||Recommended by the US EPA. Works best if air can move easily under the slab in unsilted gravel bed.|
|Passive subslab depressurization||30% - 70%||$550-$2,2250||some energy losses||Recommended by the US EPA for new construction. Depends on weather. Fan can be easily added.|
|Draintile suction||50%-99%||$800-1,700||$50-200||Works best if drain tiles form a complete loop around the basement.|
|Sump hole suction||50%-99%||$800-2,500||$50-250||Works best if air can move easily under the slab to the sump and if drain tiles form a complete loop.|
|Blockwall suction||50%-99%||$1,500-3,000||$150-400||Only for basements with hollow block walls; requires sealing of all openings.|
|Caulking of radon entry routes||0%-40%||$100-600||$0||Ignores radon infiltration through concrete. Normally used in combination with other methods.|
|Basement pressurization with a fan||50%-90%||$500-1,500||$150-500||Requires tight basements that can be isolated from outdoors and upper floors. Reduces convection but not radon diffusion - the main factor.|
|Natural ventilation through windows or vents||Variable||$200-500 if additional vents are installed||$200-700||High loss in heated or conditioned air; operating costs depend on the ventilation and utility rates. Unpredictable results.|
|Basement ventilation fan with heat recovery||25%-50% if used for full house; 25%-75% if used for the basement||$1,200-2,500||$75-500 for continuous operation||Reduces energy losses in heated/conditioned air. Works best in a tight house. May cause back-drafting.|
|RadonSeal Mitigation Method||80%-95%||$400-$700||$0||Deep-seal concrete floor and walls with RadonSeal, and seal all cracks and pathways. D-I-Y project.|
For details, see Operating Costs of ASD Radon Mitigation System.
There are five basic criteria for the optimum system:
The operational costs of radon ventilators include energy losses in heated and air-conditioned air drawn from the basement which can be several times higher than the cost of electricity.
If your basement is still unfinished and unpainted, RadonSeal makes radon mitigation quick and easy for homeowners.
The same RadonSeal method applies to buildings with foundation slabs and to houses with crawlspaces, when installing a fan-suction system may be very difficult.
RadonSeal will save the average homeowner $4,250 on installation and operation over ten years. In addition, you will have to regularly replace the fan, which is usually guaranteed for up to 3 years (US EPA). See Save $1,000's on Radon Mitigation!.
RadonSeal makes radon mitigation affordable. The spray-on application with a hand-pump garden sprayer is quick and easy. RadonSeal is a waterborne sealer, non-toxic, nonflammable, with zero VOCs. You have no reason to procrastinate!
There are no operating costs or energy losses in heated or air-conditioned air. No annoying hum of a radon fan on balmy summer nights.
The RadonSeal seal is PERMANENT – no re-application is ever needed. Unlike surface sealers or waterproofing paints, RadonSeal cannot peel or wear off and cannot be pushed out by hydrostatic pressure.
Follow the instructions and reduce the radon level below the EPA Action Limit of 4 pCi/L – backed up by an unrivaled Lifetime Money-Back Guarantee! With RadonSeal, most homeowners reduce radon to the 1 - 2 pCi/L level.
Feedback from Customers
...our basement now is reading 2.0, checked at 2 different locations. Not bad for starting at 29 pCi/L! ...
... a concrete floor and cinder block walls in my basement. I used 3 pails of Radonseal, primarily because the cinder block is so porous ...I dropped the radon reading from 18 to 0.7.
... The reading was twice the recommended safety level (8.2 pCi/L) prior to applying the seal. We applied the seal, installed an electronic permanent tester and the radon reading is now 0.2! ...
...house with radon level of 64 pCi, prior owner will not reduce or correct. In Pennsylvania (South Central). ... After RadonSeal, I saw a drop in Radon (using 72 hour electronic monitor) from 64 pCi to 2 pCi! Of course I did seal all cracks with a polyurethane made for expansion joints and cap the sump pump. ....
See more Testimonials
If you already have a mechanical radon mitigation system, RadonSeal will reduce the radon level further and in addition, will decrease the energy loss in conditioned indoor air drawn through the concrete floor to the fan.
RadonSeal is not subject to mechanical breakdowns. Apply RadonSeal as a back-up system for power outages and fan failures.
You may still need RadonSeal because it does much more than radon mitigation. It also reduces or prevents water seepage, water vapor migration, condensation, molds, mildew, and musty odors. It strengthens and preserves the concrete, reduces efflorescence and concrete dusting, and prepares the concrete for paint or adhesives.
If you have a passive sub-slab depressurization system, the radon level often depends on weather, like temperatures and wind speed. Play it safe and seal your basement with RadonSeal.
Getting a fan-suction radon mitigation installed is the only practical solution for fully finished basements. You have to find a duly certified radon mitigation contractors in your area.
Painted walls? Sealing only the floor with RadonSeal may be sufficient. Much more radon tends to penetrate through the slab than through the walls, because radon gas is trapped underneath between the footings. Soil gas outside the basement walls can easily escape upwards to the atmosphere. Many homeowners have been successful by lifting the carpet or linoleum and sealing just the floor.
If the basement floor or slab is painted or covered with floor tiles, removing the paint or tiles and adhesive is a tedious job. See more tips at FAQ.
The Consumer's Guide from EPA: "Minimize the effect of installing a radon reduction system in your house by assuring that it blends with its surroundings. For instance: radon vent pipes may be encased with materials that match the exterior of your house, or the pipes may be routed indoors up through closets. Suction systems require that one or more holes be drilled through the basement floor, preferably in a central location. The piping will likely constrain your ideas on finishing the basement."
RadonSeal eliminates the problems of unsightly piping and lost indoor space. It does not change the color or surface of the concrete in the basement.
Radon fans and piping tend to raise concern in potential home buyers, who may have never heard that there is a radioactive gas called radon. Real estate agents agree that fan mitigation systems reduce the market value of homes.
RadonSeal works invisibly in in the basement.
Radon mitigation fans draw not just soil gas from the ground but also indoor air from the house through the concrete slab. This may cause back drafting and spillage of combustion gases from the furnace, water heater, or fireplace in modern, tight houses. Installing a CO alarm with fan-based radon mitigation is a good idea! Lung cancer may kill someone in 20 years, but carbon monoxide can kill them in 20 minutes!
The risk of back drafting increases as energy-efficient houses are getting more and more air-tight. Houses are already depressurized due to the natural "stack effect" and appliances vented to the atmosphere, like combustion appliances, fireplaces, exhaust fans in the bathrooms and kitchen (may exhaust 750 cfm of air), clothes dryers, range hoods, etc. The radon mitigation fan flow of say, 100 cfm is comparable to a clothes dryer. In a leaky house, this might reduce the indoor air pressure by only 1 Pa but in a tight house, it may produce depressurization of 5–10 Pa which will reverse chimney flows. If the house is already depressurized at say 4 Pa, adding a fan-based radon mitigation system may take it over the backflow limit of 5 Pa.
Building codes recommend that each appliance should provide its own make-up air. However, they rely on passive openings and dependent on wind direction, they may actually draw more air from the house. Spillage resistant appliances (e.g. direct vent gas appliances) are a much more reliable solution.
EPA: "When radon is vented from the radon mitigation system it tends to sink and there is a danger of radon re-entering the building through doors and windows due to the vacuum ("stack") effect. To prevent re-entrainment of radon, the point of discharge from vents of fan-powered soil suction and block wall suction systems must meet all of the following requirements: (1) be above the eave of the roof, (2) be ten feet or more above ground level, (3) be ten feet or more from any window, door, or other opening, and (4) be ten feet or more from any opening into an adjacent building. The exhaust point should be positioned above the highest eave of the building and as close to the roof ridge line as possible."
RadonSeal avoids the danger of radon re-entrainment by leaving the radioactive gas where it belongs – in the ground.
Moreover, RadonSeal does not create an invisible cloud of radioactive gas which, being eight times heavier than air, tends to settle and deposit radioactive particles in the immediate surroundings of the house.
Some people believe that paints and surface sealers, particularly epoxy or rubber-based, will stop radon. However, a layer of paint or even a polyethylene sheet has no chance of stopping radon atoms. Moreover, alkalis carried by moisture from inside the concrete attack paints and cause their cracking and peeling. The US EPA has tested all possible paints and surface sealers but concluded that they are not effective.
Sheetrock, wallpaper, plaster, or even polyethylene sheets do not stop radon. Covering floors with carpeting or linoleum does not work either. Remember that even several inches of concrete cannot stop radon.
Some builders believe that the plastic vapor barrier under the slab will stop radon. Although it is a part of the "radon resistant" construction, it merely reduces the flow of soil gas. But it cannot stop the diffusion of radon and its accumulation underneath the floor. That's why EPA properly calls it the "soil gas retardant" membrane.