Thanks to Sir Isaac Newton and a story about an apple, we know that what goes up must come down. In the land of flooring adhesives, however contradictory to gravity, what goes down must come up. Many types of flooring are installed with adhesives and in most situations flooring adhesives should be removed following removal of the flooring.
Flooring adhesives should be removed for a variety of reasons. When installing flooring, it is important to have a clean subfloor surface. Failing to remove adhesives can cause problems with the installation of new glued down flooring as well as floating floors. Many new adhesives are not compatible with older adhesives and will not cure and adhere correctly to the subfloor or the new flooring.