Engineered hardwood is made up of layers which are glued together. The top layer or veneer is made of wood. This veneer ranges from 0.6 mm to 6 mm. The thicker the veneer the more times it can be refinished. The core, or middle portion is constructed of 5 – 7 layers of plywood and is available in 2 -3 layers that crisscross in different directions. Because of its construction it is more dimensionally stable than solid wood. Meaning it will not contract or expand as much due to humidity and temperature changes. The bottom of the piece of flooring is also made of wood. Engineered Hardwood is usually less expensive than solid hardwood. It can be installed on all grades, as well as over radiant heating systems and concrete. It is available in Red/White Oak, Maple, Cherry, Walnut, Hickory, Brazilian Cherry, Santos Mahogany and others, in prefinished and/or unfinished.