Can radon levels increase with a closed crawl space? Questions & Answers › Can radon levels increase with a closed crawl space? 0 Vote Up Vote Down Cimona Fernandes Staff asked 6 years ago From Hank Nolin – Crawl Spaces Can radon levels increase with a closed crawl space? 1 Answers 0 Vote Up Vote Down Cimona Fernandes Staff answered 6 years ago Sorry, you do not have access to this content. Please register for an account HERE Or if you were already approved for an account, LOG IN HERE