The floor was an engineered floor directly on slab. The surface was walnut. I do not have the actual type. On a recent similar project (have not posted pics yet, wood was cherry stained Provincial), we used a beautiful walnut Castellian floor by Mullican. My friends at Miller Flooring - West Chester, PA recommended we glue the floor and it looks and feels great. For current finished basement project (walnut or mahogany wood), we are considering Shaw engineered flooring. Hope that helps.