Hi! Our basement was a concrete slab, floor was installed by a contractor we hired directly onto concrete. He skim-coated, or evened out some areas w what I think was a skin coat. He then cleaned/scraped the floor where there were dips from what I remember, he did not do the entire floor. We used the glue down, bought the glue from Mannington. Someone in our neighborhood used the click footing and the whole basement floor buckled. We are so happy we went glue down, we have had no problems at all after 4 years. Good luck!