Dear Steve;
To mitigate possible Radon emissions into the home we mounted a continuous perforated Form-A-Drain channel to the perimeter of the inside of the exterior walls. Form-A-Drain is a rectangular plastic channel that was attached to the inside of the wall just below the slab. At two points it penetrates the exterior wall with a PVC pipe for venting. The channel was covered with a mesh and then with stone. On top of the stone and compacted foundation sand a thick insulated and reflective vapor barrier laid down. All of this was then covered with the concrete slab. The slab is monolithic in that it ties into the concrete in the ICF walls with integral rebar.
The goal of the network of perforated channel is to prevent the gasses, which naturally rise and fall depending on rainfall, to vent to the exterior instead of being forced into the home's interior by vapor pressure building up underneath the slab. If you can picture the footer and slab as being an upside down bowel you can see that even a slight change in the water table below the house results in hundreds of cubic feet or air and gasses having to escape to somewhere. Unfortunately, normally they would be forced into the home. By incorporating a network of vent channels and a barrier there is no way to build up pressure underneath the slab.
In your case I would look into ventilating or pressurizing underneath your home if this is an issue while also sealing around baseboards. In the end you want to bring in fresh air from the outside of your home and not from the soil underneath your home.
You can read more on Radon hazards, levels in your area and mitigation methods.
by going to the EPA site
http://epa.gov/radon/
Thank you for your inquiry and I wish you the best.
Benito Loyola
Last edited on Thu Sep 4th, 2008 05:40 pm by Benito Loyola
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