How a sub-slab depressurization system works

The standard radon fix is quieter and simpler than most homeowners expect. Here's what actually gets installed.

The core idea

Radon comes up out of the soil and enters through the slab, joints, and sump. Sub-slab depressurization reverses the pressure: a fan pulls air (and radon) from beneath the slab and pushes it up a pipe that vents above the roof, so the gas never reaches your living space.

The components

A sealed suction point through the slab, a run of PVC pipe routed up through the home or along an exterior wall, an inline fan (typically in the attic, garage, or outside), and a manometer gauge that shows the system is under suction. Sump pits and large cracks are sealed to make the system efficient.

What to expect

Installation is usually a single day. The fan runs continuously and uses about as much electricity as a light bulb. A proper install includes a post-mitigation test to confirm the level is now below 4.0 pCi/L.