The term floating floor refers to a variety of engineered or laminated products. These products are made up of complex dimensions that give them a stable quality, and furthermore allow for installation in areas below grade. (Below grade pertains to the location of a finished floor that is in direct contact with the ground, or with less than 18 inches of well-ventilated space). Engineered flooring systems such as Boen, Kahrs, Harris Tarkett, and serveral others, are typically made of three or more thin slabs of plywood running in opposing directions. The top layer is typically a 1/32" to 1/8" thick veneer. Yet, some of the newly developed, engineered products now have a veneer or solid wood top layer of 1/4".
Glue Down Installation Method
Modern developments in adhesive composites now make it possible to glue down a 3/4" solid wood flooring slab to a concrete base. Engineered wood flooring, (which is a sandwich of 1/16" to 1/8" inch of finish wood on top and non-finish plywood underneath), can be glued directly to a concrete base as well. Other types of flooring, such as 5/16" thick parquet, must always be glued down even if the sub-floor is wood.
Nail Down Installation Method
Generally speaking, if your sub-floor is 3/4" thick plywood or wood planks over joists, the nail down is the best installation method for you. This method usually proves to be the most economical type of installation as well.