We are looking to place this under a climbing dome for our kids in our unfinished basement. What thickness would be the best? It will be going over concrete.

Our Regrind Rolls have been used as safety flooring under playground equipment, but these rubber rolls do not feature a fall height rating. For playground equipment, we recommend using a floor that is fall height rated. All of our fall height rated flooring can be found on our Playgroud Flooring page. So you can use our Regrind Rolls, and if you do, we would recommend going with the thickest one, our 1/2" thick rolls, but we don't recommend using this flooring under playground equipment.