The Crawl Space
Some of the most challenging radon mitigation projects include addressing a crawlspace. The floors in crawl spaces can vary from bare soil to concrete covered. In the case of a concrete covered crawl space, a sub-slab depressurization system may prove successful. Where the crawlspace floor is bare soil, it will likely be necessary to install a sealed membrane and collect soil gas from below the membrane using a radon fan, a technique called sub-membrane depressurization.
Dealing with a crawl space will be more expensive than a “typical” radon mitigation project. Material costs are significantly higher (i.e., 10 mil to 15 mil membrane, sealant, mechanical battens) as are the time and effort required to install the system. Limited access and headroom are trademarks of crawl spaces and can make otherwise relatively simple tasks complicated.
The good news is that sub-membrane depressurization systems, when designed and installed properly, are very effective at mitigating indoor radon levels.