What factor influences the required size of a suction pit in a sub-slab depressurization system?

The size of a suction pit in a sub-slab depressurization system is primarily influenced by the tightness of the soil. This is because the effectiveness of the sub-slab depressurization relies on creating a vacuum beneath the foundation to draw radon gas into the system, preventing it from entering the living spaces above.

When the soil is tight or compacted, the suction pit needs to be larger to create a sufficient pressure differential that can overcome the resistance of dense soil. This larger size helps to ensure that there is an adequate volume of air that can be drawn from the beneath the slab, effectively reducing radon concentrations. Conversely, if the soil is loose or well-drained, a smaller suction pit may suffice, as the gas can be more easily extracted.

Understanding the characteristics of the soil surrounding the foundation helps in designing an effective radon mitigation system that is tailored to the specific conditions of the site.