Radon System

Radon System

A “radon system” is usually a fan-and-pipe setup that controls air pressure under your home so radon doesn’t seep inside. The right system is tailored to your foundation and then verified with testing. This page explains the main radon system types, what parts matter most, and how to spot quality.

Radon is a radioactive gas found naturally in soil and rock. It can enter homes through openings in the lowest level. Long-term exposure raises lung cancer risk, and there are no immediate symptoms to warn you.

EPA recommends taking action at 4.0 pCi/L, and many people also reduce levels between 2.0 and 4.0 pCi/L when practical.

The main types of radon systems you’ll hear about

Most residential systems fall into a few buckets:

Active soil depressurization (ASD)
The most common solution for basements and slabs. A fan draws air from beneath the slab and vents it outdoors.

Crawl space membrane systems
A sealed liner covers soil, and suction pulls radon from beneath that liner before it enters the home.

Passive radon systems
Sometimes installed in new construction, passive systems rely on natural stack effect. They can help, but may need a fan added to reach strong reductions in many cases.

A good contractor should explain why your home needs one type over another, using your foundation details as the reason.

What parts matter most in a radon system

People focus on the fan brand, but performance often comes down to design choices:

Suction point quality
A small suction pit under the slab can improve communication. In some homes, a single suction point won’t reach the whole footprint.

Pipe routing and joints
Long runs and too many bends can reduce airflow. Loose joints can leak. Either problem can reduce results.

Fan placement
Fans should be positioned to avoid pushing radon into living space if a leak occurs. Attics, garages, and exteriors are common options.

Exhaust termination
Exhaust must release where it won’t re-enter the home. EPA’s consumer guidance covers safe discharge practices and homeowner awareness.

Monitoring
A manometer gives you quick confirmation the fan is creating suction. It’s a simple part that can prevent months of “silent failure.”

Fast Facts: why a radon system still needs retesting

A radon system is mechanical. Fans age, power interruptions happen, and renovations change air pressure. Retesting is the only way to confirm continued performance. CDC and EPA-aligned guidance emphasizes testing and reducing elevated levels.

What “success” looks like after installation

Success means:

• Radon levels are reduced in a post-mitigation test
  
  

• The monitor indicates stable operation
  
  

• Noise is acceptable
  
  

• The discharge is clearly outside and away from openings
  
  

• The homeowner understands what to watch for
  
  

If any of those are missing, the system may still work, but you’re missing protection and proof.

Common Questions Around Radon System

Is a radon system loud?
Most are quiet when mounted correctly and when vibration is controlled. Noise usually comes from poor mounting or pipe contact with framing.

Does every home need the same system?
No. A slab, basement, crawl space, and mixed foundation homes often need different approaches.

How do I know if my radon system is running?
Check the manometer or installed indicator. If it shows a different reading than normal, call for service.

Can a radon system run in winter and summer?
Yes. Systems typically run continuously to keep pressure stable.

What if my radon is high only sometimes?
Short spikes can happen, but mitigation decisions should be based on reliable testing and how the space is used.

Related Terms
Active soil depressurization, radon vent pipe, radon manometer, crawl space membrane, radon discharge point

Additional Resources

1. https://www.epa.gov/sites/default/files/2016-12/documents/2016_consumers_guide_to_radon_reduction.pdf
   
   

2. https://www.cdc.gov/radon/prevention/index.html
   
   

3. https://www.usgs.gov/data/geologic-radon-potential-map-united-states
   
   

Expand Your Knowledge
EPA action level explanation: https://www.epa.gov/radon/what-epas-action-level-radon-and-what-does-it-mean.
ATSDR radon FAQ PDF: https://www.atsdr.cdc.gov/toxfaqs/tfacts145.pdf.
Missouri radon testing page: https://health.mo.gov/living/environment/radon/testing.php.