How Does Radon Enter a Home?

Radon, because it is a gas, is able to move through spaces in the soil or fill material around a home’s foundation. This regions homes tend to operate under negative pressure-this is especially true in the lowest portions of the home and during the heating season. This negative pressure acts as a vacuum (suction) that pulls soil gases, including radon, into the lower level of the structure. Some causes of home vacuum are:

• Heated air rising inside the home (stack effect).
• Wind blowing past a home (downward draft effect)
• Air used by fireplaces, wood stoves, and furnaces (vacuum effect).
• Air vented to the outside by clothes dryers and exhaust fans in bathrooms, kitchens, or attics (Vacuum effect). 

Radon can enter a home through floors and walls—anywhere there is an opening between the home and the soil. Examples of such openings include dirt floor crawlspaces, unsealed sumps, cracks in slab-on-grade floors, utility penetrations, and the tiny pore spaces in concrete block walls. A basement, of course, provides a large surface area that contacts soil material.