How Does Radon Enter My Home or Business?

Radon is present nearly everywhere in the soil. Radon gas is able to move up through the porous dirt and rocks and into the air we breathe. When it seeps into an otherwise enclosed space, like a home or business, it accumulates and becomes a health concern.

Radon is drawn into your home anywhere there is an opening between the structure and the soil:

  1. Cracks in concrete slabs
  2. Spaces behind brick veneer walls that rest on uncapped hollow-block foundations
  3. Pores and cracks in concrete blocks
  4. Floor-wall joints
  5. Exposed soil, as in a sump or crawl space
  6. Drain tile, if drained to an open sump
  7. Mortar joints
  8. Loose fitting pipe penetrations
  9. Open tops of block walls
  10. Building materials: brick, concrete, rock
  11. Well water (not commonly a major source in Minnesota homes)


The radon gas is drawn upward into your home or business because of the normal patterns of air flow that cause a vacuum effect inside the structure.

These effects are especially stronger in the winter, because the warmer air inside the home has a lower pressure than the colder outside air. As warm air rises to the upper portions of a building, it draws radon in from gaps and cracks in the foundation and basement slab.

In addition to that, appliances like hot water heaters and appliance exhaust fans, as well as heating sources like furnaces and fireplaces can draw air upward out of the underlying soil.