I bought a house recently that had a radon level of 4.1 (just over epa standards) which I believe is due to a crawl space section, below a later addition, that has a dirt floor. Instead of spending $3k on a mitagation system, as well as labeling my home as a radon site, neither option improving the homes value... I'd like to put in a concrete vapor barrier. The question is how much concrete is needed in this situation. The area will only be used for storage. I've been told 3-4 inches by some, I'd appreciate any advice.

 

Concrete will not stop radon! It will go through a concrete floor. Allso one high test does not mean you have a radon problem. Id do two more test one long and one short!

 

I must admit, I'm more than a bit confused. The EPA website says that one of the primary ways radon comes into the home is through cracks in the foundation. I assume these cracks to be in concrete. Why wouldn't a concrete barrier/floor stop the radon from entering the house from the soil? Other than taking additional tests to confirm the actual level, how would one handle the problem without the mitigation system (which I absolutely refuse to do)? Thanks for the comment, I appreciate any and all advice.

 

Only other way that I know about is to bring in outside air to dilute the radon!

 

I you are concerned, just put down a real vapor barrier (10 mil & cheap) and a 4" concrete slab.

Seal the joint between the concrete/vapor barrier and the walls completely to prevent any leakage IF there actually is any radon.

After that, you can choose whether you want to vent the space or not.

One of the problems with using big fans to vent, they are only effective if they lower the air pressure, which can draw or suck radon gas from the ground where the vapor pressure is higher.

If you have an adequate barrier in your crawl space, any radon will take the path of least resistance and exit out around you house (through the soil), where Mother Nature will handle it as she has aways done.

 

Is it of value to spread sheeting on the crawl space dirt floor and without sealing it up the side walls? A inspector told me that I should just LAY the sheeting out on the dirt to stop the transfer of moisture due to seasonal weather changes . The space is DRY, but does show signs of past moisture stains. Very faint though. The crawl space it approx. 48" deep for your infomation.

Also isn't the proper way to prepare a crawl space is to TOTALLY seal it, and do away with outside vents?

Thank You,


Dale