Radon in Granite


Recent media attention has focused on granite countertops and whether they can increase your indoor radon levels. While testing your home is always a good idea, a few clarifications are in order. However after reading below if you still feel that you would like to test your counter top please contact us to receive your granite counter top radon test kit.

FACT - All natural products, especially stone, minerals, and sand, contain trace amounts of some radioactive elements called NORMs (Naturally Occurring Radioactive Mineral) that can produce measurable amounts of radiation and sometimes radon gas.
This includes all concrete products, clay bricks, most non-plastic plates and dishes, coal and the flyash produced in coal-fired power plants, natural gas (contains radon), phosphate fertilizers used in your garden (ALL contain potassium and small amounts of uranium and thorium), and the vegetables grown using those fertilizers. The Border Patrol often catches truck loads of marijuana because it is loaded with radiation producing potassium), all glass made using silica (even eye glasses, wine glasses, mirrors, windows, etc.), and granite too. There are thousands of items we could list.
However, the key word is "measurable". As an illustration, compare the radon produced by your naturally-occurring stone surfaces, such as granite, to the heat produced by a birthday candle. Although you wouldn't be able to heat your entire kitchen using a birthday candle you can easily feel the heat if you put your hand over it. This is similar to placing a geiger counter over a tiny speck of uranium, thorium, radium, or potassium. The detector will make thousands of clicks per minute but be of little concern. If your stone surface emits a small amount of radon, as happens in most cases, it will generally be insignificant when diluted with the quantity of air in your entire home.
You are hundreds of times more likely to be at risk for radon emanating from the soil beneath your home. The US EPA states it simply in the Consumer's Guide to Radon Reduction: "In a small number of homes, the building materials (e.g., granite and certain concrete products) can give off radon, although building materials rarely cause radon problems by themselves. In the United States, radon gas in soils is the principal source of elevated radon levels in homes."

Radon Resistant New Construction

All new homes built today in Minnesota are required to have a radon reduction system in order to meet the current building code. These systems are typically a simple passive system which may not be completely effective. By simply adding a fan to the passive system any remaining radon level can be reduced significantly and inexpensively.

These construction techniques help block radon from entering the home. The occupants will benefit from lower radon levels in their new home. They are easy to upgrade when there is a need to increase the radon reduction. If high radon levels are found, the techniques allow for easy and inexpensive installation of a fan for increased radon reduction in the home. Every new home should be tested for radon by the homeowner after occupancy. They are cost-effective for home buyers. It is more cost-effective to include radon-resistant techniques while building a home, rather than installing a radon reduction system in an existing home.

These are typically the steps a contractor now takes to reduce radon when building a new home.

  • Gas Permeable Layer is placed beneath the slab or flooring system to allow the soil gas to move freely underneath the house. In many cases, the material used is a 4-inch layer of clean gravel.
  • Plastic Sheeting is placed on top of the gas permeable layer and under the slab to help prevent the soil gas from entering the home. In crawlspaces, the sheeting is placed over the crawlspace floor.
  • All openings in the concrete foundation floor are sealed to reduce soil gas entry into the home.
  • A 3- or 4-inch gas-tight or PVC pipe (commonly used for plumbing) runs from the gas permeable layer through the house to the roof to safely vent radon and other soil gases above the house.