What if I have tested my home or building and have found elevated radon levels?
If you have found elevated radon levels in your home or building, there is no need to panic or move out. Fixing a structure with an elevated radon problem is quite easy. Over the years radon experts and certified radon mitigators have designed and proven several methods that will reduce the elevated radon level in a structure to below 4.0pCi/L. This method is known as the installation of a radon reduction system, which is meant to create a greater vacuum on the soil directly beneath the structure than the structure itself is creating on the soil. Your house or building type will determine which type of radon reduction system should be installed into the structure.
*U.S. EPA, Consumer’s Guide to Radon Reduction: How to Fix Your Home
Buildings are generally categorized by foundation type and design. In the picture above, the techniques for basements and slab on grade or poured concrete on soil foundations are typically the same. The techniques used for crawl spaces are slightly different, but still involve a basic fan and PVC pipe system that reroutes the radon gas from entering into the structure and vents it out and above the structure. Many structures may have multiple foundation types and will require a combination of methods tied into one system with one fan or could require separate systems installed.
Techniques used for basement, slab on grade foundations and crawl spaces
Active Soil Depressurization or Subslab Depressurization is commonly used to treat basements, slab on grade or crawl space foundation types. This technique creates a vacuum on the soil that is greater than the vacuum the structure itself is creating on the soil. The gas is then sucked and vacuumed through a core in the concrete floor for basements and slabs on grade or from under a plastic sheeting that has been sealed to the walls of the crawl space.The radon flows through a 4” diameter PVC pipe and is routed eitherwithin the structure to the attic and out through the roof or through an exterior wall where it is then discharged above the eve of the roof.The system may also be connected through a water drainage system, such as a sump pump or perimeter drain. This type of technique can be used as a passive device or an active device. Sealing up all cracks, holes around plumbing and floor to wall joints with a polyurethane caulk, will help to make your system more energy efficient. This will also help to reduce the amount of conditioned air from being sucked or drawn out of the house and into the radon reduction system. Passive: A passive system uses natural stack effect to suck and guide the radon gas through the radon reduction system and out above your structure to the outside air. Stack effect is the natural movement of air through a structure and is caused by the difference in indoor to outdoor air pressure, temperature and moisture. For example: if it is colder outdoors, there is more pressure outside and/or moisture and if it is warm indoors with less pressure and moisture, then the air will be naturally pushed into the structure. The structure will also suck on the ground due to opening and closing of doors and windows, air exhaust vents, heating and air conditioning units and other appliances. A passive radon mitigation system is usually installed during construction and runs within the structure to the attic and out through the roof, and is hidden within the walls. It can also be installed after construction and run through closets and storage areas and up through to the attic, so that is hidden and out of sight. Active: An active system contains a low voltage fan, which runs continuously once the system is properly installed and turned on. The fan runs constantly and helps to create a vacuum under the slab or plastic sheeting of the structure. The vacuum that the fan creates sucks the gas through the PVC pipe and reroutes it up and outside the structure. This system is more effective on radon gas than the passive system, especially in areas with expected elevated radon levels. The fan uses the same amount of energy as a 60 watt light bulb. In new construction the structure may be built with a passive system. This technique is much more efficient because a fan can be added later to turn it into an active system. Radon Resistant New Construction (RRNC) requires the system to be installed during the construction of a building or house. This allows for a certified mitigator to treat the soil before the concrete slab is poured or to treat the crawl space prior to the floor being added on. It is much easier and more efficient to pour a layer of clean aggregate and install a perforated pipe or corrugated mat beneath the concrete slab or along the floor of the crawl space and add a riser before it has been poured or covered. RRNC is covered under Appendix F of the International Residential Code used by building departments (see Appendix F). If your county or city does not have Appendix F adopted into the building codes please call your building department, city council and county commissioners to encourage them to adopt Appendix F for all new and existing construction.
For more information: Consumer's Guide to Radon Reduction How to Fix Your Homewww.epa.gov/radon/pubs Protecting Your Home From Radon A Step-By-Step Manual for Radon Reduction 2nd edition Center for Environmental Research and Technology, Inc. http://certi.info Appendix F http://www.co.el-dorado.ca.us/bos/wwwroot/attachments/9b0786a4-885f-4fb4-9aa1-66eb00a40af3.pdf *Information was provided by the U.S. Environmental Protection Agency, Consumer's Guide to Radon Reduction How to Fix Your Home, the Center for Environmental Research and Technology, Inc.
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