What factor contributes most to the success of a sub-slab depressurization system?

The success of a sub-slab depressurization system is primarily influenced by the clean aggregate under the slab. This layer plays a crucial role in facilitating the efficient movement of air and radon gas from beneath the slab to the suction points and ultimately to the outside atmosphere. If the aggregate is clean, it allows preferential pathways for air to flow, which helps in effectively reducing the radon levels inside the building.

In contrast, if the aggregate is poorly compacted or contains debris and other materials, it can impede airflow, which in turn would limit the system’s ability to draw out radon gas efficiently. This can lead to higher concentrations of radon remaining indoors despite the presence of a mitigation system.

While the other factors, such as the quality of the radon detection system, type of sealing material, and number of suction points, have their importance in the overall strategy for mitigating radon, they do not directly influence the fundamental airflow dynamics beneath the slab to the same extent that clean aggregate does. Hence, the quality of the aggregate under the slab stands out as the most critical factor in ensuring that a sub-slab depressurization system operates effectively.