Crawl spaces
We have two crawl spaces in our basement. These are spaces underneath the kitchen and back family room which were both added on sometime after the house was built, and thus they are outside the foundation. So there are two openings in the foundation (see photo) to access these spaces. Some of our radon problem could be because of the dirt ground in these spaces, which allows radon to seep in. The crawl space under the family room actually has an old cistern underneath. The cistern is half filled with construction waste (see close up photo), including pieces of plaster and concrete block.
Crawl Space
Cistern
For radon mitigation, the floor of the crawl spaces need to be sealed with plastic and a pipe connected to it to draw out the radon that accumulates underneath. The cistern is problematic, because the plastic sheet would not be supported underneath. Solution? We decided to “temporarily store” some of our demolition waste (sheet rock, plaster, lathe) in the cistern until it was full. Now the plastic sheet can be laid on top. Problem solved.