Radon Mitigation Systems in New Construction

Date Published: October 13, 2022

If you are a Colorado resident, you are likely aware of the dangerous, radioactive gas, radon. It is prevalent in many CO regions, and prolonged exposure to it can cause serious health issues. Radon mitigation systems are the best way to keep toxic levels of radon to a minimum in the residential setting. That’s why these systems have grown to be such an integral part of newly constructed CO homes.

The Environmental Protection Agency (EPA) compiled a map that illustrates the level of radon risk in every county of the United States. As you can see from the map below, almost all of Colorado is in Zone 1, which is the highest radon risk.

EPA map of radon zones

Image sourced from: https://www.radonzone.com/

The ICC and Radon Mitigation

The International Code Council (ICC) established a guidebook of codes to which newly constructed homes must adhere. Most of the standards in the guidebook are required in all new homes. However, there are certain items mentioned in its appendix portion that are not actually required by the ICC.

One such section is the appendix about radon control methods, which states:

“This appendix contains requirements for new construction in jurisdictions where radon-resistant construction is required.”

ICC logo

Image sourced from: fiscalnote.com

Because levels of radon vary from region to region throughout the country, it isn’t always necessary to install mitigation systems. For instance, there are areas in the southern parts of the nation that are in Zone 3 with very low risk and no need for mitigation. Thus, the ICC leaves it up to the individual municipality to make the final call.

Radon Mitigation Code in Colorado

In Appendix AF Radon Control Methods, the ICC provides a list of CO counties that are at high risk for radon exposure – and there are a lot of them. Certain areas, such as Boulder County, Larimer County, and the City of Longmont are acting accordingly and making radon-resistant construction a must for new builds.

At the time of this writing, the policy has not been uniformly adopted throughout the whole state. However, homebuyers will often still opt for radon-resistant builds, due to the state’s high radon risk.

With Colorado building code becoming stricter and more energy/safety conscious, it would not be surprising to see the whole state make radon-resistant new construction mandatory in the near future.

Ok, let’s say your area does require radon-resistant construction measures to be taken. Or maybe it’s not required, but you’d still like to take the extra precaution and get a system installed. What steps do you need to take to make sure your new build fits the qualifications? Well let’s take a deeper dive into the ICC’s radon control requirements.

ICC Radon Reduction Requirements

  1. A layer of gas-permeable material must be installed under the slab and all floor systems that are in direct contact with the ground and within the house foundation.
  2. A soil-gas-retarder of approved material must be placed securely over the entire surface area of the aforementioned gas-permeable material.
  3. Any openings or entry routes (i.e. floor openings, condensate drains, sump pits etc.) that could permit the flow of radon must be sealed properly.
  4. Some type of passive radon mitigation system must be installed, depending on the configuration of the home.
  5. The vent pipe must be accessible in the attic space or somewhere outside the habitable space in case fan installation is needed in the future.
  6. Exposed interior portions of the radon mitigation piping must be labeled, in order to be properly identified.
  7. A power source must be available in an anticipated location in the case that active fan installation is needed.

Diagram showing radon mitigation techniques for different foundation types

Diagram showing radon mitigation techniques for different foundation types

Diagram showing radon mitigation techniques for different foundation types. Image sourced from: https://codes.iccsafe.org

Once construction is complete and the structure meets all the necessary criteria, a radon test is required to measure the effectiveness of the newly installed radon mitigation system.

If radon levels reach above 4.0 picocuries per liter (pCi/L), then it will be necessary to install an active fan on the already existing passive radon system. This upgrade should reduce the radon levels significantly, with the target being below 4.0 pCi/L.

For more details, visit the Radon Control Methods section of the International Residential Code guide.

Radon Measurement Testing

As mentioned above, once you build the system, you have to test. You want to make sure that, after all that hard work that goes into protecting your property from radon gas, your system is actually functioning properly!

Now it’s time to call a radon testing pro. Here at Scott Home Inspection, we have full staff of NRPP-certified home inspectors that are ready to provide you with professional, reliable and efficient radon testing services. If you are in need of a radon test, feel free to reach out for more info or to schedule your test today.

radon mitigation system manometer

The differential on the blue manometer indicates that this mitigation system is pressurized and functioning properly.

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About the Author: Chris Kimmel

Chris Kimmel worked as an Associate Home Inspector for two years, handling numerous services including sewer scope inspections, pest inspections, mold air sample testing, radon testing, and water quality testing. Chris now works with Scott Home Inspection as a Content Writing Specialist.

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