What is sub-slab depressurization?

Sub-slab depressurization (SSD) is a radon mitigation technique that creates negative air pressure beneath your home's concrete slab. By pulling air from under the slab with a fan, the system prevents radon gas from entering your home through foundation cracks and openings. The radon is instead vented safely above the roofline.

How do I know if my SSD system is working?

Every properly installed SSD system includes a U-tube manometer — a simple visual indicator that shows whether the fan is creating suction. When the liquid levels in the two sides of the U-tube are unequal, the system is working. Annual retesting of radon levels is also recommended.

Can SSD be installed in a finished basement?

Yes. Certified technicians can install sub-slab depressurization in finished basements with minimal disruption. The suction point can be placed in a utility area, closet, or along a wall, and piping can be routed through walls or to the exterior.

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Sub-Slab Depressurization

The most effective and widely-used radon mitigation technique. Creates negative pressure beneath your foundation to prevent radon entry.

Typical Cost$1,000 – $2,500

Timeframe3-5 hours installation

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About Sub-Slab Systems

Sub-Slab Depressurization (SSD) is the gold standard of radon mitigation, used in over 90% of residential installations. The system works by creating a vacuum beneath your home's concrete slab, reversing the pressure differential that draws radon into your living space. A small hole is cored through the slab, PVC piping is connected, and a fan continuously pulls radon gas from beneath the foundation and vents it safely above the roofline.

Key Benefits

Most effective radon reduction method — 90-99% reduction typical

EPA and WHO recommended as primary mitigation technique

Works for basement and slab-on-grade foundations

Quiet operation — modern fans produce minimal noise

No disruption to your living space after installation

System lasts 20+ years with minimal maintenance

How It Works

Foundation inspection to determine optimal suction point location

A 4-5 inch hole is cored through the concrete slab

Aggregate or soil beneath the slab is excavated to create a suction pit

PVC piping (3" or 4" diameter) is connected and routed to the exterior

A radon fan is installed in the attic or on the exterior wall

Pipe exits through or along the roofline, venting radon above the home

All visible cracks, gaps, and penetrations in the slab are sealed

A U-tube manometer is installed to monitor system performance

Ideal For

Homes with poured concrete or concrete block basement floors
Slab-on-grade construction (no basement)
Homes with finished basements where interior routing is preferred
Most residential radon mitigation situations

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