The wear layer is the top layer of hardwood veneer that is glued on the top surface of the core of hardwood, plywood or HDF. The thickness of the wear layer determines how many times you can sand and refinish your engineered floor: 2-3 times for a 4mm wear layer, or 4-5 times for a 6mm wear layer. If you clean and maintain your floor correctly it shouldn’t need to be sanded unless you want to change the colour.