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Radon Mitigation Methods for Homes

Radon levels can be reduced

According to the US EPA recommendations, you should mitigate if your radon test reads 4 pCi/L or higher, and consider radon mitigation if your radon level is above 2 pCi/L. Fortunately, radon mitigation is very effective. You will likely end up with a healthier home than your neighbors, who barely meet the EPA's action limit. There is a number of issues to consider when choosing the best radon mitigation method for your home:

Installation costs of radon mitigation

EPA: "The average house costs about $1,200 for a contractor to fix, although this can range from about $800 to about $2,500, depending on the characteristics of the house and the method used."

RadonSeal can save you hundreds of dollars - the typical cost is only $400-$600. The spray-on application is quick and easy for homeowners.

Appearance of the house

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 space. It does not change the color or surface of the concrete. There is no annoying hum of a radon fan on balmy summer nights.

Market value of your home

Fan-based radon mitigation systems tend to raise concern in potential home buyers, who may have never heard of radon. Real estate agents agree that they significantly reduce the market value of the house.

RadonSeal works invisibly inside the concrete.

Operating costs of radon mitigation systems

EPA: "Systems that use fans are more effective in reducing radon levels; however, they will increase your electric bill. Remember, the fan should never be turned off; it must run continuously for the system to work correctly. A warning device must be installed to alert you if the system stops working properly."

RadonSeal has zero operating costs and is not subject to mechanical breakdowns or grid failures. If you already have a fan-based radon mitigation, apply RadonSeal as a back-up.

Maintenance costs of radon mitigation systems

EPA: "Radon reduction systems need occasional maintenance. Warning device should be checked on a regular basis to make sure the system is working correctly. Fans may need to be repaired or replaced (manufacturer warranties usually do to exceed three years). Replacing a fan will cost around $250. Testing radon level at least every two years will confirm that the fan is still performing well. The filters in an Heat Recovery Ventilation system require periodic cleaning and should be changed twice a year, and the ventilator should be checked annually by a professional to make sure the air flow remains properly balanced."

RadonSeal has zero maintenance costs. Re-application is not needed. The seal is permanent.

Energy losses of radon mitigation systems

EPA: "Most types of radon reduction systems cause some loss of heated or air conditioned air, which could increase your utility bills. How much your utility bills will be affected depends on the climate you live in, what kind of reduction system you select, and how your house is built."

There are zero energy losses with RadonSeal. In fact, if you already have a radon mitigation system, RadonSeal will reduce its energy losses by stopping the suction of treated air through the slab into the radon fan.

Re-entrainment of radon gas

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 dangers of radon re-entrainment by leaving the gas where it belongs - in the ground. It does not create an invisible cloud of radioactive gas which, being 8 times heavier than air, tends to settle and deposit radioactive particles in the immediate surroundings.

The RadonSeal mitigation method

Unlike paints or surface sealers, RadonSeal penetrates deep inside concrete (up to 4") and permanently blocks the seepage of radon by sealing the capillaries in concrete. RadonSeal must be applied to all concrete in contact with the ground, be it a basement or a foundation slab.

RadonSeal seals the concrete. Afterwards, all cracks or openings have to be sealed and caulked just like with any other radon mitigation method (details in Application Instructions). By using RadonSeal, most homeowners reduce radon to the 1 - 2 pCi/L range. The theoretical bottom limit is the natural level of radon in the ambient air, which averages 0.45 pCi/L in the U.S. but exceeds 1 pCi/L in some areas.

RadonSeal Method - A Comparison of Features
Method	Typical Radon Reduction	Typical range of installation costs	Typical operating cost range for fan electricity and heating/cooled air loss* (annual)	Comments
RadonSeal deep-penetrating concrete sealer	80%-99%	$400-$900	$0	A quick and safe application.

Over ten years, RadonSeal saves the average homeowner $2,300. See Radon Mitigation Savings.

Mechanical radon mitigation methods

(Source: "The Consumer's Guide to Radon Reduction" by EPA)

Covering exposed earth in basement reduces ingress of radon, as does sealing cracks and openings in ground level walls and floors.

Drain-tiles can be placed surrounding the foundation and vented away from the house (the drain-tile suction method). This method is designed to pull radon from the soil surrounding the house and vent it away from the house.

Sub-slab suction is more difficult to accomplish, as it involves placing pipes under the house (laterally through side walls or by drilling holes in the concrete slab). A fan is used to vent these pipes away from the house.

Concrete block walls can be vented by sucking air from the hollow spaces in the wall and venting it away from the house to prevent radon from re-entering.

Lastly, there are methods for decreasing negative pressures within the house by bringing air into the house in proportion to losses from chimneys, dryers, etc., or by positive pressure including basement pressurization by blowing air from upper floors into the sealed basement.

Radon Mitigation Methods - A Comparison of Features
Method	Typical Radon Reduction	Typical installation costs (contractor)	Typical operating costs for fan electricity and energy loss in heated/cooled air (annual)	Comments
Fan-based mitigation system (sub-slab depressurization)	80%-99%	$800-2,500	$75-175	Works best if air can move easily under the slab - a gravel bed. Recommended by the US EPA.
Drain-tile suction with a fan	90%-99%	$800-1,700	$75-175	Works best if drain tiles form a complete loop around the basement.
Block-wall suction with a fan	50%-99%	$1,500-3,000	$150-300	Only in basements with hollow block walls, requires sealing of all openings.
Sump hole suction with a fan	90%-99%	$800-2,500	$100-225	Works best if air can move easily under slab to the sump and if drain tiles form complete loop.
Caulking of radon entry routes	0%-50%	$100-600	$0	Ignores radon infiltration through concrete. Normally used in combination with other techniques.
Basement pressurization	50%-99%	$500-1,500	$150-500	Requires tight basements that can be isolated from outdoors and upper floors. Unpredictable results.
Natural ventilation through windows or vents	Variable	$200-500 if additional vents are installed	$100-700	High loss in heated or conditioned air; operating costs depend on the ventilation and utility rates. Unpredictable results.
Heat recovery ventilation	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 deep-penetrating concrete sealer	80%-99%	$400-$900	$0	For unfinished basements. Like with fan systems, all openings, gaps, and cracks have to be sealed or caulked.

Other radon remediation ideas

There is a common belief that radon should be reduced by venting the basement. But depending on the house construction and tightness, it may actually increase the inflow of radon from the ground. The high energy losses in heated or conditioned air make this method impractical.

Some people believe that paints and surface sealers, particularly epoxy or rubber-based, 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 the paint and cause its cracking and eventual peeling. 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 retards 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.

Finished or painted basements

Getting a fan radon mitigation installed may be the best or easiest solution for fully-finished basements.

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. Although the result cannot be guaranteed, many homeowners are 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 Application Instructions.

RadonSeal provides additional savings

If you install a mechanical radon mitigation system, the basement and the concrete will still need additional care and expenses like waterproofing, repair, preservation, preparation for painting or floor tiles.

RadonSeal does much more than radon mitigation. It also stops or prevents water seepage, water vapor migration, condensation, molds, mildew, and musty odors. It strengthens and preserves the concrete, stops efflorescence and concrete dusting, and prepares the concrete for painting or adhesives.

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