I have a house with slightly elevated radon levels on the ground floor. I received a tip to start by sealing around all penetrations for pipes and similar from the crawl space to the entrance floor. The problem is that the gaps between, for example, a drainpipe and the "ceiling" in the crawl space are between 3-8 cm wide. Not something you can fill with any radon-resistant sealant.
What is suitable to use? Some expanding foam? Some mesh? Some kind of adhesive patch? Some special product?
What is suitable to use? Some expanding foam? Some mesh? Some kind of adhesive patch? Some special product?
Wide Butyltape might work to use.