The prevalence of Radon Gas in the soils in areas around the United States is an issue of growing concern. Radon has been deemed the number 1 cause of lung cancer in non-smokers in a study done at the University of Iowa. Radon gas is found in varying levels in almost all regions of the country. Visit the EPA's Radon Map Zone at the following link.
Radon Map Zone Areas in Pink pose the highest risk followed by Orange and Yellow. Click here to check the specific risk level in your county.
If your planned home is in an area of higher risk, you should plan early on to install a Radon Mitigation System. In many areas now, a test is required with each real-estate transaction regarding residential properties and this will probably expand to include most of the higher risk areas. In any event, your health is well worth the small investment to install such a system.
Installing the basics of the system in a Basement or Slab-On-Grade Foundation consists of inserting a perforated pipe below the slab in crushed rock and stubbing up a connector into the basement. Venting this pipe to the exterior (away from any windows in your house or your neighbors, preferably up through the roof), contitutes what is known as a Passive Radon Mitigation System. If , after your house is complete, a test determines that levels are still too high, you may have to convert to an Active Radon Mitigation System by installing a fan than runs continuously which creates low pressure under the slab and increases the rate of gas evacuation. So you will want to have the slab penetration in an area that is readily accessible and has electric available to power the fan.
Many times the fan is located in the attic, particularly if your foundation is slab-on-grade or crawl space. Also remember that you will want to make sure that the vent through the roof does not allow water to fall down the pipe to the slab below, this would not be a good thing for several reasons.
Designing and installing the infrastructure for a passive system can be accomplished for about $150 to $300. this will save you 150-300% of the cost of retrofitting. An Active systems will add $ 250-$550 depending on the size of your home. Download Build Radon Out; a guide on the design and construction of Radon Mitigation Systems and 'Model Standards and Techniques for Control of Radon Gas'.