Wood flooring once required little more decision-making than a choice of tree and finish. In the 21st century, however, wood is no longer just wood. In addition to traditional solid-wood flooring there are materials engineered from mixtures of wood and products that laminate wood with resins and other materials. There's no straight-line spectrum of quality across these types. Instead there is a range of products within each type.
Solid Wood Flooring
The classic wood floor can be composed of planks or smaller pieces, simply laid down parallel to each other or arranged in patterns, such as parquet. The thickness of the wood ranges from 3/4-inch down to 5/16-inch. Solid wood is most often installed and then finished, which reinforces one of its greatest advantages; you can sand off an old finish or a stain any time and refinish to change the look. Solid wood flooring is not recommended for basements because of the danger of warping.
Engineered flooring is a plywood that can give essentially the same look as solid wood, but is not prone to warping so can be used below ground level. The layers of the plywood may be as thin as veneer, so there's less depth for sanding down and refinishing. Engineered flooring is kept from warping because the top layer, with the grain of the wood running along the plank, is backed by a layer with the grain running across the width of the plank.
Flooring made from bamboo may look like bamboo or very much like certain hardwoods. The U.S. Green Building Council's Buyer's Guide says it actually makes a harder flooring material than red oak or maple. Bamboo is technically a grass, and generally grows in tubes of various diameters. The tubes are slit and the pieces glued side by side to make the top layer or full thickness of flooring material. They can be "horizontal," just as if the tube has been opened up to make a plank, or "vertical," spooned together with their edges up and looking more like a hardwood grain. Vertical bamboo has more depth for refinishing. Bamboo grows very quickly, and can be grown and harvested in an environmentally sustainable way.
Laminated Mixed Materials
Not all laminated flooring is wood, and when it does look like wood, it will still have a protective transparent layer on top. The core of laminated flooring is high-density fiberboard, and under that is a layer of melamine resin. A layer of underlayment may be part of the flooring material, or may be laid in larger sheets underneath the flooring. This kind of flooring cannot be refinished, and both its look and other characteristics depend on the particular product and manufacturer.