Engineered wood floor construction consists of 3 to 10 layers of wood (typically 5). Each layer of wood is called a "ply" and they are oriented in different directions for strength, then glued under pressure. This construction technique results in a wood floor that is more stable than a solid wood floor. Stable meaning the floor is less susceptible to shrinkage and expansion movement due to fluctuations in humidity or temperature. These floors are also able to be installed directly over concrete and may be installed in below grade applications unlike solid wood floors.
Another feature of these floors is that they come in standard tongue and groove and can be installed using nails, floating (requires glue) or some manufacturers offer interlocking engineered floating wood flooring that requires no glue. These interlocking floating wood floors are the easiest to install and require no specialized tools.
