To understand diagnostics, it may first help to understand the most common approach to radon mitigation, the sub slab depressurization system. While there are other techniques to radon mitigation which may be more appropriate to your home, depressurizing the slab, or creating a vacuum under the slab is usually the most effective.
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First, we create a suction point by drilling a 4” hole in your slab. A pipe is routed between this suction point and the depressurization fan. Finally, a duct is routed from the fan to an area where venting is appropriate. This system acts as one big vacuum pulling air from under your slab.
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When we perform a visual investigation of the structure, we can see where we can place this suction point and ductwork. But there are some things we cannot see visually. Is the aggregate under the slab made up of rock, cinder ash, sand or clay? Was the foundation blasted and if so how deep is the box of rocks we are trying to create a vacuum go?
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If clay is the aggregate, is trying to create a vacuum with limited porosity achievable or even reasonable and is there a better technique such as a Heat Recovery Ventilator? Does the area under the slab come in contact with a karst formation where location of the suction points is strategic?
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Pre mitigation diagnostics eliminate the guesswork. Instead of installing a big system (like the one described above) to answer these questions, a portable smaller scale vacuum system can give us the data we need to help give us eyes where we can’t see.
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This involves drilling several small holes (about the size of you index finger) in the slab, attaching our vacuum, adjusting the airflow and taking digital readings across the slab to determine the system’s effectiveness and what type of fan will be most appropriate. Holes are patched and this process in most cases takes about half an hour.
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Diagnostics reduce the risk of our initial system needing another suction point, a different type of fan, or needing to be relocated altogether.
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