Comparison of Radon Mitigation Methods

How to Reduce Radon in Your Home

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:
$800-2,500
$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.

How to Select the Best Radon Mitigation System?

There are five basic criteria for the optimum system:

  1. The lowest radon level.
  2. The installation cost to homeowners.
  3. The operational costs.
  4. The noise burden in the living areas.
  5. Impact on the appearance of the house.

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.

Do-It-Yourself Radon Mitigation in Two Basic Steps

If your basement is still unfinished and unpainted, RadonSeal makes radon mitigation quick and easy for homeowners.

Step 1: Seal the concrete floor and walls with RadonSeal Deep-Penetrating Concrete Sealer
RadonSeal penetrates deep into concrete (up to 4"), chemically reacts, and permanently seals the pores against water, water vapor, and even radon gas. If there is no basement, seal the foundation slab or the floor of the crawlspace.
Step 2: Seal or caulk all openings, gaps, or cracks as required by all radon mitigation methods.
DIY Foundation Crack Repair Kits for cracks in poured concrete walls
CrackWeld Floor Repair Kits for cracks in concrete floors
ElastiPoxy Joint & Crack Filler for expansion control joints and for open floor-to-wall joints.

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.

The Advantages of RadonSeal Mitigation

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.

Add RadonSeal to Your Fan-Based Mitigation Systems

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.

Already Finished or Painted Basements?

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.

Appearance of Your House

fan radon mitigation system

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.

Protect the Market Value of Your Home!

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.

Back Drafting and Fan-Suction Mitigation Systems

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.

Avoid 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 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.

Other Radon Remediation Ideas

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.