What method is proven to most effectively reduce radon levels in homes with crawl space foundations?

The most effective method for reducing radon levels in homes with crawl space foundations is sub-membrane depressurization. This technique involves placing a vapor barrier, or membrane, over the ground in the crawl space and then creating a negative pressure beneath this membrane. A fan is typically used to draw air from beneath the membrane and vent it outside the home.

This approach is particularly effective in crawl spaces because it not only mitigates radon gas that may be seeping in from the soil but also addresses moisture issues, which can also be a concern in these areas. By lowering the pressure beneath the membrane, radon is prevented from infiltrating into the living spaces of the home, thereby significantly reducing indoor radon levels.

In contrast, ventilation systems can improve air circulation and may help to some extent, but they do not target radon specifically and may inadvertently increase radon levels if not designed properly. Sealing all openings can reduce radon entry, yet it is not a foolproof method since radon can still seep through unssealed pathways in the foundation. Installing air filters can remove airborne particles but does not directly address the radon gas itself or its entry points. Therefore, sub-membrane depressurization stands out as the most