My old vinyl sheet floor in my kitchen had discoloration in several places. When I removed it, I saw moisture under much of the old floor. I have been told not to put a sealer on the cement before putting on a new floor because it would prevent the adhesive from sticking. What should I do? Is there a type of vinyl flooring that will not become discolored from the moisture? Is there something I should put between the slab and the floor? Thanks for any help.