I have a shed with concrete slab on foundation. They never put any poly down before pouring the concrete. Now every time we get a lot of rain (I’m in Houston), moisture comes up through the slab. Adding drainage all around the building helped somewhat but I really want to put down laminate flooring.
Does  anybody know of some kind of spray or roll on water barrier that I can apply to the slab before putting down flooring? Kinda like the stuff the pour on garage floors? Would that work? I’d appreciate any ideas y’all might have!