Radon - one or two?

Concrete caulk or something else? Would painting the flooring with Dryloc do much? I heard that you can only slow it down/reduce it, you can’t stop the entry of radon, even with plastic sheeting etc.

I’m not sure about the best caulking product, Peter. I think entry through the slab itself is minimal. It’s a gas, so the amount by which you can lower Radon levels depends on how tightly and permanently you can seal the points of entry.