Recently, several of our neighbors have discovered high Radon rates in their homes, which all have basements. I'm in the process of getting my home tested now, which is a crawlspace structure.
If the Radon tests come back showing high levels what is the most cost-effective way to reduce the radon levels? I've been looking into crawlspace ventilators, but I don't know how effective they are against radon.
I have passive radon mitigation in my crawl space. Didn't want it, but it is required here. The building code (IRC 2003 at the time) specified how it was to be done. It's exactly as Windows on Wash described. It vents up through the roof through a 4-inch pipe next to the soil stack. It's passive, meaning there is no fan or ventilator.