Reference
Radon Mitigation System Types
Most residential systems share the same principle and differ in where the suction is applied. Which approach fits a building is a design question answered on site — not something that can be selected from a catalogue.
The approaches side by side
| System type | Where suction is applied | Typically considered when |
|---|---|---|
| Sub-slab depressurization | Beneath a concrete slab, through one or more cored suction points. | The building has a basement or slab-on-grade floor with permeable material beneath it. |
| Drain-tile suction | Into an existing sub-slab drain tile loop. | The building has a functioning drain tile system that communicates under the slab. |
| Sump-hole suction | Into a sump pit connected to drain tile, under a sealed cover. | A sump pit already ties into sub-slab drainage and can be sealed without impairing the pump. |
| Sub-membrane depressurization | Beneath a sealed membrane laid over exposed crawl space soil. | The building has a crawl space with an earth floor. |
| Passive system | No fan — relies on natural stack effect in a vent pipe. | Installed during construction as radon-resistant new construction. |
| Active system | Fan-driven continuous suction with a monitoring device. | Reduction must be reliable and verifiable. |
| Multi-zone system | Separate suction points serving distinct foundation areas. | Additions, split foundations or poor communication under a large slab. |
Passive compared with active
A passive system is a pathway without a driver. It can reduce indoor radon, but the effect varies with temperature, wind and how the building is operated, and there is no indicator confirming it is working.
Adding a fan and a monitor turns that pathway into a system whose operation can be observed. Whether an existing pipe is suitable for that conversion is an evaluation question.
What every active system has in common
Suitability depends on the building
The deciding factors are the foundation construction, what sits beneath the slab, whether distinct foundation areas communicate with each other, where piping can physically be routed, and where an exhaust can terminate safely.
Diagnostic measurements taken during a site visit — rather than the radon reading itself — are what tell a designer how many suction points a building needs.
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