We often think of the foundation of a building as being absolutely solid. While this is the ultimate goal, it is not often true. Buildings can sometimes be faced with a phenomenon known as vapor intrusion. Contaminated groundwater or soil can emit dangerous gasses that find their way up and into structures.
An important factor to consider when building in Los Angeles is the presence of the natural gas methane in the soil.
Passive vapor barrier mitigation systems generally involve two main components: the sub-slab ventilation system, and the actual membrane engineered to block vapors from passing through.