Sub-Slab Depressurization Testing

How Sub-Slab Depressurization Testing Works

Sub-slab depressurization testing is primarily used for radon mitigation system verification, but also provides valuable information for slab leak investigations. A small fan or vacuum is connected to a test hole through the slab, and the pressure field beneath the slab is measured at monitoring points across the floor area. The pressure readings reveal the extent of the sub-slab communication and the effective radius of the depressurization system. For leak investigations, this testing can identify areas where water is flowing beneath the slab by measuring pressure changes that correlate with moisture. It also helps identify the extent of soil saturation around slab leaks, informing the scope of repair work needed.

Applications in BC

• Radon mitigation system performance verification
• Slab leak extent assessment through pressure field analysis
• Sub-slab moisture migration path identification
• Under-slab drainage system effectiveness testing
• Concrete slab condition assessment prior to flooring installation