Engineered wood floors are generally 3, 5, 7 or 9 thin wood plies (called veneers) that are laminated together with special glues under heat and pressure to form a single wood plank. Engineered plies In the manufacturing process the thin wood plies are stacked on top of each other, but generally in opposite directions. This creates a floor that is much more dimensionally stable and far less effected by moisture than a solid hardwood floor.
Engineered wood floors range from 1/4" to 9/16" in thickness, and from 2 1/4" to 8" in width with random lengths. The top finish layer is cut from a variety of North American hardwoods as well as many different types of exotic wood species. The top wood ply is also generally sliced cut, rotary cut, or sawn. Each gives a unique visual to the wood face.
Hardwood engineered floors are often confused with laminate floors because they are constructed of several wood plies that are laminated together. Laminate flooring is constructed differently and uses a photo print to simulate the appearance of real hardwood flooring. (Note: there are some laminate floors that have a thin ply of wood veneer as the top layer and use a fiber core underneath.)
These floors are the best choice for installing over concrete slabs and in basements. You should still check if excessive moisture and humidity are not present. (Note: concrete slabs must still be dry, clean and fully-cured.)
Engineered Wood FloorsWood always wants to expand in a certain direction. Solid wood planks will always expand in the presence of moisture across the width of the planks, rather than down the length of the boards. To avoid the expansion/contraction problem, manufacturers of engineered wood planks place each ply in the opposite direction of each other. This is called cross-ply construction and is what gives engineered wood floors their dimensional stability. If humidity is a concern, then you should strongly consider an engineered wood floor or rather than a solid wood floor.
Another advantage of engineered wood floors is the top ply can be a wide variety of wood species without driving the manufacturing costs out of sight. Thus, engineered hardwood floors are offered in a variety of American hardwoods, as well as many exotic hardwood species. If you a looking for some of the more unusual, or exotic wood species than you should definitely take a look at manufacturers offering engineered hardwood floors.
Most engineered floors can be installed several methods, including: nailed-down, stapled-down, glued-down, or floated over a wide variety of subfloors, including some types of existing floors. Caution should be used when attempting to go over an existing floori to be sure the existing flooring is well adhered and that your installation application meets the manufacturer's installation recommendations.