What is the objective of a sub-slab or sub-membrane depressurization system?

The objective of a sub-slab or sub-membrane depressurization system is to create a vacuum beneath the foundation. This vacuum effectively reduces the pressure in the sub-slab space, thus preventing radon gas and other soil gases from infiltrating into the building. By lowering the pressure under the foundation, the system ensures that external air, which generally has a higher pressure than the vacuum created, does not push these harmful gases up into the living space. The technique is a key method in radon mitigation, targeting the source of radon accumulation and effectively managing it before it reaches inhabited areas.

In contrast, creating a layer of sand beneath the foundation, establishing an impermeable barrier, or setting up a high-pressure system would not directly achieve the objective of reducing radon levels in the home. Sand layers may contribute to drainage, an impermeable barrier could prevent entry of gasses but would not actively reduce pressure, and a high-pressure system would encourage gas infiltration rather than mitigate it.