Types of Systems
Radon Mitigation Active Soil Depressurization Interior Installation
The EPA’s most recommended method for radon reduction. It has proven successful in small residential homes as well as large, multi-story buildings. Its long range success is dependent upon the quality of the installation and the design reflecting the construction characteristics of the building. Radon reduction is achieved by generating negative pressure under the slab floor.
Active Soil Depressurization Exterior Installation
Similar to the interior system except that the piping is placed on the exterior of the building. The design of this system requires a thorough knowledge of construction and building techniques to insure that damage is not done to the foundation or the plumbing and electrical systems of the building. In most cases the exterior piping can be designed to blend esthetically with the exterior appearance of the building. This type of system is generally used when construction features prevent the installation of an interior ASD system.
Crawlspace Sub-Membrane Depressurization
A home or building which has a crawlspace can be handled in two ways. One, to utilize a method called sub-membrane depressurization. This involves installing a network of 4 inch corrugated pipe on the surface of the dirt floor. Then cover the entire dirt floor of the crawlspace area with a polyethylene vapor barrier (plastic sheeting). We recommend a 10 mil thickness. The four inch pipe then exits to the outside where it is attached to a radon exhaust fan. When installing the vapor barrier for best results we recommend over lapping any seams 12 inches and seal them with duct tape or spray adhesive. Seal the plastic around any pillar or pipe etc…Also we wrap the plastic up any wall at least 12 inches and seal it to the wall with either spray adhesive or urethane caulk. As with an ASD system the exhaust of the fan must vent above the roof line. When the fan is activated it will draw the radon from below the plastic before it can enter the crawlspace and the structure. The radon will vent above the roof where it will quickly dilute to the outside air. This is recommended for a structure with a crawlspace were the radon levels may be only slightly elevated, little ventilation exists and/or limited room to work. The idea is the same as the sub-membrane system except no vapor barrier is installed. The system shall remove the crawlspace air before it can enter the home through the floor. You may even install a network of 4-inch duct within the crawlspace when more than one cavity is present. The 4-inch duct would then attach to the intake side of the exhaust fan. The installation of additional vents creating more circulation of fresh air may work. This is always recommended first. You may even add a small ventilation fan to help circulate the air and introduce some fresh air. However be aware that in cold climates you may freeze the plumbing pipes.
Commercial Mitigation Applications
Installation of radon mitigation systems in commercial buildings requires a more in-depth knowledge of construction and building techniques. The basic theory of radon reduction is the same as that applied to residential buildings. But since building codes and construction designs are much different, the mitigation contractor must be thoroughly knowledgeable of building codes and construction practices to avoid damaging the structure or violating the building’s structural integrity. Often commercial builders of apartments, nursing homes and office buildings incorporate Radon Resistant Building Standards into their buildings during construction.