The most effective way to lower indoor radon levels is to remove the gas before it has time to build up in the home. Active Soil Depressurization (ASD) is a proven method preferred by the EPA and most professionals for successful radon mitigation.
Certified Radon Technologies installs pre and post construction ASD radon systems for both commercial and residential applications. Below is an illustration showing three typical residential ASD system configurations.
This is an example of an exterior ASD system. This arrangement generates a negative pressure underneath the floor slab and exhausts the soil gas above the roofline. A suction pit is dug out underneath the floor in order to help facilitate the movement of gas away from the house. This type of design has proven very effective in radon mitigation and offers indoor air quality benefits as well.
Sump Pit/ Drain Tile Depressurization
This system is installed directly to an available sump pit and exhausted out the attic. Drain tile connected to the sump pit and acts as a conduit for soil gas. Negative pressure created from the fan then removes the gas. When installing these systems it is important that the pit is properly sealed and a view port is added to the sump cover especially when water removal is an issue.
Homes with exposed soil beneath the structure will need this type of system in order to effectively remove soil gas. Perforated pipe is laid down along the crawl-space surface and a two-ply polyethylene barrier is placed over the exposed soil and pipe. The system is properly sealed, connected to the fan and the soil gas is vented outdoors. This type of system is typically more expensive to install.