Solid wood products consist of strips (2 1/4″ wide) or planks (at least 3″ wide) made from one piece of wood through its thickness, usually 3/4″ thick. Many solid wood products must be nailed down, therefore, the subfloor must be wood in order to install solid hardwood flooring. Some exceptions are solid wood clip systems like “Junkers”.
Engineered wood floors consist of three or more layers of wood glued together with the face (top) layer and back (bottom) layer grain running parallel or the same direction. The center (core) layer is turned 90 degrees during assembly and the glue used in the assembly is stronger than the wood itself. With engineered products, as the fibers in each layer absorb moisture and want to expand, each layer is restrained by the other and improved dimensional stability results.
Ultimately, the customer has for their floor, a product that displays far less expansion ann contraction with moisture changes and therefore can be successfully installed below grade, in basements, in humid climates, and even fit tight to vertical surfaces. This, of course, is very different from solid floors. The floor can be glued directly to concrete with several adhesive types.
A major concern with engineered products is longevity. Customers want to make sure that their wood can be sanded and refinished. In most cases the engineered floor can be sanded and refinished. Of course, the entire life wear and appearance of the floor rests in the thickness of the top layer of wood. With proper maintenance, the initial service life can be expected to be 20-30 years. Many of the laminated floor products on the market today can be sanded and refinished, using the proper techniques and equipment, at least twice.