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Related Items: Build Radon Out

is a colorless, odorless, tasteless, and chemically inert radioactive gas. It is formed by the natural radioactive decay of uranium in rock, soil, and water. Naturally existing, low levels of uranium occur widely in Earth's crust. It can be found in all 50 states. Unless you test for it, there is no way of telling how much is present.


If you live in certain parts of the United States (EPA Radon Map), you might be aware of the threat that radon gas poses. Radon gas is radioactive, and in tightly insulated houses it can accumulate to concentrations that pose a health threat. If you inhale the gas into your lungs, its decay can increase your chance of getting lung cancer. A study reported in 1990 by the National Safety Council estimated that about 14,000 deaths a year could be attributed to radon, and that the number could range from 7,000 to 30,000.

New homes can be built with radon-resistant features.

Radon-resistant construction techniques can be effective in preventing radon entry.  When installed properly and completely, these simple and inexpensive techniques can help reduce indoor radon levels in homes.  In addition, installing them at the time of construction makes it easier and less expensive to reduce radon levels further if these passive techniques don't reduce radon levels to below 4 pCi/L.  Every new home should be tested after occupancy, even if it was built radon-resistant.  If radon levels are still in excess of 4 pCi/L, the passive system should be activated by having a qualified mitigator install a vent fan. 

Radon Test Kit Coupon
The NSC offers low-cost short- and long-term radon test kits (.pdf, 26 KB) which include lab analysis and return postage. Kits can also be ordered directly from the Helpline, (800) 557-2366, with a credit card payment.

Radon-Resistant Construction Techniques

There are five major parts to the passive radon-resistant system:

  1. A layer of gas-permeable material under the foundation (usually four inches of gravel)
  2. Plastic sheeting over the gas-permeable material
  3. Sealant and caulk on all openings in the concrete foundation floor
  4. A gas-tight three- or four-inch vent pipe that runs from under the foundation through the house to the roof
  5. A roughed-in electrical junction box for the future installation of a fan, if needed

These features create a physical barrier to radon entry. The vent pipe prevents radon from entering your home by drawing the radon from below the house and venting it to the air outside where it then dilutes with the outside air.

For more explanation of radon resistant construction techniques, refer to EPA publication, Building Radon Out: A Step-by-Step Guide on How to Build Radon-Resistant Homes (.pdf, 8.15 MB).

David Smith, Instructor
Building Trades * 2205 Forest Drive SE * Cedar Rapids IA 52403
FAX 319 398-2016 * Phone 319 431-0674

Comments/Questions, dsmith@cr.k12.ia.us

1998/2013, Cedar Rapids Community Schools
Last updated, 11/21/2012