Engineered hardwood flooring is constructed by bonding multiple layers of wood together and the top layer or ‘wear layer’ is the surface of the flooring that is walked on.
The wear layer is the chosen species of wood, for example, Walnut or Oak and once the flooring has been installed it is almost impossible to tell the difference between engineered wood flooring and solid wood flooring by sight alone.
Underneath the wear layer are multiple layers of wood that have been glued together at 90 degrees to each other to give dimensional stability to the planks of flooring. This method of construction means that engineered hardwood flooring is more resilient to temperature and humidity than solid wood flooring.
The wear layer of engineered wood flooring is generally between 2.5mm and 6mm in depth, depending on the quality and type of flooring you wish to purchase. It must be thicker than 2mm, otherwise it is classed as veneered wood flooring. Also, it is important not to mistake engineered wood flooring for laminate flooring, which does not consist of any hardwood at all. 
The thickness of the wear layer of engineered hardwood flooring will gradually get worn down with time due to daily wear and tear. If the wear layer needs sanding and re-finishing this can be done without any problems, as long as you do not sand through the wear layer into the base layers of the planks of flooring. So, a thicker wear layer will inevitably give your flooring a longer life.
