Radon prevention from the beginning

Radon prevention from the beginning - Image 1


By building Radon resistant homes, builders and contractors are providing a public health service by helping to reduce a buyers risk of lung cancer from exposure to radon in indoor air. These radon-resistant homes can be an important selling point for health conscious home buyers. It is generally more cost effective to include radon-resistant features during new construction than it is to mitigate the home after construction. While the techniques may vary for different house foundations and building site requirements, there are five basic features that builders should include to prevent radon from entering the  home.

1.    Gravel:

A 4 inch layer of clean, coarse gravel below the foundation will allow soil gases including radon to move freely under the house.  This is called the “air flow layer” or “gas permeable layer” because the loose gravel allows the gasses to circulate. 

2.    Plastic Sheeting or Vapor Retarder 

Heavy duty plastic sheeting or a vapor retarder is placed on top of the gravel to prevent the soil gasses from entering the house. The sheeting also keeps the concrete from clogging the gravel layer when the slab is poured.

3.    Vent pipe

A 3 or 4-inch solid PVC pipe, like the ones commonly used in plumbing, is installed vertically from the gravel layer through the house’s conditioned space. And roof to saefely vent radon and other soil gasses outside the house. This pipe should be labeled “Radon System”. 

4.    Sealing and Caulking

Seal all openings, cracks and crevices in the concrete foundation floor (including the slab perimeter crack) and walls with polyurethane caulk to prevent Radon from coming into the home.

5.    Junction Box

Install an electrical junction box near the PVC pipe inside for use with a radon fan. This is an important feature because many passive radon systems need to be activated to work. To activate a passive system all that needs to happen is to have a Radon Fan connected to the Junction box.


The only catch to these Radon resistant constructions is that they have to be activated to work properly. Unfortunately, many homebuilders don’t understand Radon or how to reduce it, so they install the system incorrectly. That’s why it’s highly recommended you have an NRD dealer involved in the process from day one so the system is designed correctly. 

For more information on how to properly mitigate your home for Radon, contact The Foundation Guys.

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The Foundation Guys Inc.
1294 Algoma Rd
Gloucester, ON K1B 3W8
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