Radon Resistant New Construction - EH: Minnesota Department of Health

Radon Resistant New Construction

If you plan to build a new home, plan to build it radon-resistant. It is much safer for your family and far more cost-effective to prevent radon from becoming a problem. Radon-resistant construction combines common building techniques and materials to seal entry points and route the gases outdoors, helping to prevent radon from entering the home.

Is there a way to test the soil before building?

Testing the soil prior to building cannot predict what the radon levels will be once the house is completed. The impact that the site preparation will have on introducing radon pathways into the home, and the extent or affect air pressure will have in the finished home, can affect radon levels and your exposure.

Are there different types of systems?

There are two types of systems:

  • Passive system is a minimal approach to radon reduction that relies on the convective flow of air upward in a vent pipe to exhaust the radon gas. The State Building Code only requires a "passive" system be installed. However, a fan may need to be added at a later date if radon levels are still high.
  • Active system, gold standard, offers maximum radon reduction through the use of a fan that continuously pulls radon-laden air from the soil and exhausts it outdoors. The active system can make a big difference in reducing radon exposure. Minnesota contractors are required to install an active system in order for their home to receive the Gold Standard designation.

Features of radon-resistant construction

Diagram of Radon Resistant New Construction features
  1. Electrical junction box - An electrical junction box is roughed in the attic near the vent pipe. This power supply will be ready to use if the radon control system needs to be "activated" in the future.
  2. Aggregate - Four inches of clean aggregate is spread under all areas within the home's walls that will be covered by concrete slabs. Soil-gas collection mats or drainage mats can also be used.
  3. Vent pipe - The vent pipe runs vertically through the roof, directing the soil gases to the outdoors. The vent pipe is a 3 to 4 inch diameter PVC pipe that is connected to the "T" in the aggregate. If the home has a sump pit or drain-tile system, the vent pipe can be inserted directly into the sump pit or connected to the drain-tile loop.
  4. Roof flashing - Flashing must be installed around the vent pipe where it exits the roof to prevent leakage.
  5. Sealing - All potential soil gas entry points are sealed with caulk or expanding foam. Sump baskets must have sealed cover.
  6. Vent pipe "T" - A "T" fitting made of 3 to 4 inch diameter PVC pipe is inserted into the aggregate under the basement slab, or under a crawl space's vapor barrier. The "T" pipe allows soil gases to enter with little resistance, and connects to the main vent pipe.
  7. Soil-gas retard er - To help keep water/moisture in concrete so that it fully cures with minimum cracking. 6 mil thick polyethylene sheeting, over lapped 12 inches at the seams, and fitted closely around all penetrations, is placed over the aggregate. In crawl spaces, the sheeting is sealed to the foundation walls and interior piers.

What are the benefits of building a radon-resistant home?

It reduces your risk of lung cancer. People who live in a radon-resistant home will breathe in less radon. The less radon you are exposed to, the lower your risk of lung cancer.

System components are incorporated into the building design. When radon-resistant features are part of the design, they can easily be hidden from view. This may be possible if a radon mitigation system has to be added at a later date, after the house is finished.

It may add value when you sell. Potential buyers should be reassured when a home is built radon-resistant. Informed shoppers will view this as a positive feature in the Minnesota housing market.

What should I do if the radon level in my new home is high?

If unacceptable radon levels are present, and the home has a passive radon system in place, it can be upgraded to an active system by adding and activating an in-line radon fan. Typically a monitor device is also installed with an active system.

In-line Radon Fan - The fan is wired into the electrical junction box that was roughed in. This pulls radon and other soil gases from beneath the home and exhausts them to the outdoors.

Monitor Device - A system failure warning device should also be installed to alert you if the system malfunctions. The most common warning device is a u-tube. A u-tube visually indicates whether or not the fan is running.

Updated Friday, January 26, 2018 at 02:23PM