sub-slab depressurization 12

https://aged-wiki.win/index.php/Understanding_Radon_Fan_Replacement_Cost_in_St._Louis

Sub-slab depressurization is a technique used to control soil gases like radon or vapor intrusion under a building's foundation. It works by creating a low-pressure zone beneath the concrete slab using a fan or passive system, which pulls these gases away from the structure before they can seep inside. This method is common in new or retrofitted homes to improve indoor air quality, but it requires careful installation to avoid disturbing the soil or groundwater.