Though solid-wood flooring is a perennial favorite, engineered-wood flooring has soared in popularity in recent years. Engineered-wood floors are generally more affordable and easier to install than their solid-wood counterparts, and they can be laid down below grade (below ground level) and on any type of subfloor.

Engineered-wood flooring has a thin layer of hardwood bonded to two or more layers of less costly wood backing, such as plywood, MDF (medium-density fiberboard), hardboard, or particleboard. This oftentimes significantly reduces the cost.

The hardwood veneer, or “wear layer,” generally ranges from 0.6 to 5 millimeters in thickness. Try to buy the thickest top layer you can afford as the thickness determines how many times you will be able to sand down your floor and, therefore, how long your floor will last. A good product should allow you a complete sanding two to three times over the lifetime of the floor; a lesser-quality product can only be sanded once.

Beneath this veneer sit 3 to 10 cheaper wood layers, usually made of plywood. These “plys” lie one on top of the other, with the grain pattern alternating direction with each layer. This construction is what gives engineered-wood flooring its strength and stability and also makes the floor less susceptible to the expansion and shrinkage caused by fluctuations in temperature and humidity that solid hardwood floors experience. Because of these qualities, engineered-wood flooring can be installed in areas where solid-wood flooring typically cannot, such as over concrete subfloors or in basements.

Most engineered floors are installed over plywood subflooring, but they can also go over smooth concrete slabs or existing, sound vinyl flooring.  On a plywood subfloor, some types can simply be glued down with adhesive.

As with solid-wood floors, engineered-wood planks and strips feature tongues and grooves (tabs and slots) on their long, vertical sides, which allow them to fit together. Unlike solid-wood floors, however, engineered-wood floors can be “floated”—installed without gluing or nailing down the planks or strips to the subfloor.

Some engineered products, often called “click-together” or “lock-and-fold” floors, allow you to snap them in place without the need for adhesive between the strips or planks. The floor rests on a thin foam pad. Over concrete, a barrier of 6-mil plastic seals out moisture.