Radon Resistant New Construction
Radon Resistant New Construction (RRNC) integrates the key features of the ideal radon reduction system into the design phase of the home from the ground up.
The sub-grade must be a highly permeable rock or gravel. A polyethylene membrane separates the sub-strata from the concrete slab. The building pad should be high enough to ensure drainage away from the house. Excess moisture in the sub-slab strata would hinder the lateral flow of the soil gases toward the vent pipe and reduce the effectiveness of the whole system. All the sub-soil gases should flow freely from the farthest reaches of the slab to a single riser.
The vent pipe can route up through a utility chase near the center of the house to maximize the stack effect and induce upward impetus to the soil gases to enhance the passive system. By a passive radon reduction system lowering the sub-slab pressure a fan may not be required. If any further reduction is necessary, maximum reduction can be achieved by adding a fan.
In most homes over crawl spaces where the sub-strata is clay, a perforated pipe can be run under the radon resistant membrane to aid in the collection of soil gases. In order to draw soil gases from the sub-membrane strata and reverse the pressure, all edges, seams, and penetrations must be sealed .
A radon test is conducted when the house is occupied. If a passive system yields low radon levels, there is a savings in power and maintenance costs. If the fan is required, it is a simple addition and will surely be effective.