New Construction

The easiest way to ensure there are low radon levels in a building, is to install a system at the time of construction. When systems are designed and installed to produce the desired conditions below the slab, low radon levels are achieved. Active Soil Depressurization systems installed at the time of construction have also been found to have significant moisture reduction benefits.

The system consists of several components:
 A four (4) inch layer of gravel is installed under the slab. The void spaces in this layer provide a capillary break and good air flow through the sub-slab area.  A four (4) inch diameter, slotted pipe is installed inside the perimeter of the footing, under grade beams and across large open areas. This provides a sub-slab plenum that is used to provide even air flow and pressure under the slab.
 The sub-slab collection pipe(s) is connected to a “T” with a PVC pipe stubbed upward to connect to the above slab vent system.
 A 6-mil poly sheet is installed above the aggregate to keep moisture away from the slab and the void spaces in the aggregate from filling when the slab is poured.
 After the slab is poured and the framing of the house completed, four (4) inch foam core PVC pipe is connected to the stubbed connection to the sub-slab plenum and run up through the framing, into the attic and through the roof deck. The pipe terminates twelve (12) inches above the shingles.
 The most important component of the ASD System is the fan. When power has been provided to the house, the fan can be activated. This will provide air flow and negative pressure under the slab.