ACTIVE SYSTEM
Active systems can be installed "at the time of construction of the home or a passive system can be
upgraded to an active system if the home is found to have elevated levels of radon above 4 pC/1.
Active systems have proven effective in lowering radon in homes where elevated levels have been
found. Active systems are simply passive systems with the addition of a fan to more actively draw
radon from the soil into the stack where it dissipates into the atmosphere.  It also includes a
system-failure warning device. All homes should be tested for radon; if levels above 4 pC/1 are found,
ttie passive system should be upgraded to an active system.
6.     System-failure warning device.

7.     Fan installed in stack.
Note: For more information on either active or passive systems, see ASTM Standard Guide 1465-92
(American  Society of Testing and  Materials), or call  the Radon Division ,of the U.S. EPA

                      RADON-RESISTANT  TECHNIQUES
                               FOR NEW HOME CONSTRUCTION
                               -           PASSIVE SYSTEM

          The techniques described below have proven to be effective in reducing the entry of radon gas into .a.
          home and preparing the home for easy installation of an active radon control system.  This approach
          utilizes barriers to radon entry and stack effect reduction techniques to reduce the rate of radon entry,
          plus the installation of a FVC pipe running from beneath the slab to the roof. The radon is drawn from
          beneath, the slab into the stack and vented into the air above the roof where it dissipates. All new
          homes should be tested to ensure that the passive system has lowered the radon level below 4 pC/L If
          the level is above 4 pC/1, the system can be modified by the addition of a fan and warning device (see
          other side).




Layer of gas permeable material, such as clean gravel, 4" thick.

Continuous layer of polyethylene sheeting under entire slab, overlapped at seams, to serve as a

Sealing and caulking of any openings through ttie slab and foundation walls, such as drains,
sumps, utility penetrations, and floor-wall joints to retard soil-gas entry.

Installation of 3"-4" PVC pipe that extends from the gas permeable layer to the roof.

Roughed-in wiring for later installation of fan and system-failure warning device, if radon test
shows elevated levels.
i	!-!	':