Solid

Solid hardwood floors come in a wide range of dimensions and styles, with each plank made of solid wood and milled from a single piece of timber. Solid hardwood floors were originally used for structural purposes, being installed perpendicular to the wooden support beams of a building. Modern construction techniques now rarely use wood building frames and solid hardwood floors are used almost exclusively for their appearance.
For flooring, solid wood has many limitations due to the natural characteristics of wood. Expansion and contraction of wood from moisture and temperature fluctuation puts many dimensional restrictions on solid wood floors. Typically, 5" wide and 3/4" thick boards are the largest that can be manufactured from solid wood without compromising the structure of the flooring (some manufacturers produce wider boards using proprietary milling techniques). There is, however, no standard size which will perform well in every environment. For contemporary construction techniques, the most significant characteristic of solid wood floors is that they are not recommended to be installed directly over concrete.



Engineered

Engineered wood flooring is composed of two or more layers of wood in the form of a plank. The top layer (lamella) is the wood that is visible when the flooring is installed, and is adhered to the core (or substrate) which provides the stability. Laminate, vinyl and veneer floors are often confused with engineered wood floors - laminate uses an image of wood on its surface, vinyl is plastic formed to look like wood, and veneer uses a thin layer of wood with a core that could be one of a number of different composite wood products (most commonly, high density fibreboard). Engineered wood is the most common type of wood flooring used globally. North America is the only continent that has a larger solid wood market than engineered, although engineered wood is quickly catching up in market share.